# Absolute and Relative Gas Concentration: Understanding Oxygen in Air. Bruce Bugbee and Mark Blonquist

Save this PDF as:

Size: px
Start display at page:

Download "Absolute and Relative Gas Concentration: Understanding Oxygen in Air. Bruce Bugbee and Mark Blonquist"

## Transcription

1 Absolute and Relative Gas Concentration: Understanding Oxygen in Air Bruce Bugbee and Mark Blonquist Absolute and Relative Gas Concentration Gas concentration is described in two ways, absolute and relative concentration (Table 1). The ideal gas law yields absolute gas concentration [mol m -3 ]: PV = nrt (1) where P is pressure [Pa], V is volume [m 3 ], n is gas quantity [mol], T is temperature [K], R is the ideal gas constant (8.315 J mol -1 K -1 ), and rearranging Eq. (1) to solve for n / V [mol m -3 ] yields absolute gas concentration (Table 1). However, the simplest and most common way to report the concentration of a specific gas in a mixture is by expressing it relative to the other gases in the mixture, as a fraction or percentage (Table 1). For example, the amount of oxygen (O ) in the atmosphere, assuming there is no water vapor in the atmosphere, is kpa O per kpa air or 0.95 %. The atmospheric concentration of O has remained constant for several hundred years at 0.95 %. The percentage is the same at sea level or on Mount Everest. However, the absolute O concentration does not remain constant. An O tank is required to climb Mount Everest, even though the relative O concentration is still 0.95 % (Fig. 1A). The absolute O concentration determines the rate of most biological and chemical processes, but the relative O concentration is typically reported. This is analogous to discussing relative humidity when absolute humidity is what determines evaporation rates. Absolute and relative gas concentration measurements can be expressed using several different units (Table 1). Table 1. Units used to describe absolute and relative gas concentration measurements. Absolute Amount of Gas moles of O per unit volume (e.g. moles per Liter) mass of O per unit volume (e.g. grams per Liter; O has a mass of 3 g per mole) partial pressure (e.g. kilopascals [kpa]) Relative Amount of Gas % O in air (e.g % in ambient air) mole fraction (e.g. moles of O per mole of air; mol O per mole of ambient air; this can also be expressed as kpa O per kpa air) Effect of Barometric Pressure on Gas Concentration The ideal gas law (Eq. (1)) shows that absolute gas concentration increases by % at sea level for every 1 kpa increase in pressure (1 kpa / kpa = ). For a sensor that measures absolute gas concentration but is calibrated to read out in relative units, a 1 kpa pressure increase at sea level results in an apparent O increase of 0.07 % ( * 0.95 % =

2 0.07 %) and an apparent relative O concentration of %. The relative gas concentration didn t really increase, but the absolute concentration, which is what sensors measure, did change. This shows up as an apparent change in relative concentration. Due to lower barometric pressure at higher elevations (Fig. 1A), the percentage increase in absolute gas concentration per kpa increases with elevation. For example, at an elevation of 1358 m (Logan, Utah), the barometric pressure is approximately 86 kpa and the absolute gas concentration increases by 1.16 % for every 1 kpa increase in pressure (1 kpa / 86.0 kpa = ). Again, for a sensor that measures absolute gas concentration but is calibrated to read out in relative units, this results in an apparent O increase. In this example, 0.47 % O for every 1 kpa increase in barometric pressure ( * 0.95 % = 0.43 %) and an apparent relative O concentration of %. A barometric pressure correction should be applied to all O sensors that are calibrated to read relative O concentration. The equation to correct O measurements for barometric pressure at any elevation is: BP M BPC O = OM 1 () BPC where O M is measured O concentration [%] (the apparent O concentration), BP C is barometric pressure [kpa] at the time of calibration, and BP M is barometric pressure [kpa] at the time of the measurement. Approximate barometric pressure for a given elevation is calculated from: E BP AVE = (3) where E is elevation [m]. In order to make a barometric pressure correction on gas measurements, it must be continuously measured as it changes over time. The typical annual range is approximately 4 kpa, or the average pressure for a given elevation +/- kpa. The apparent effects of barometric pressure on relative O measurements, based on calculations from Eq. (), are plotted for 1358 m elevation (Fig. 1B) to show the significance of measuring and correcting for barometric pressure. If not accounted for, barometric pressure fluctuations show up in the O measurement as a change in relative O concentration because sensors respond to absolute O concentration, but are generally calibrated to read relative O concentration.

3 Figure 1: A) Barometric pressure and absolute O concentration [mmol / L] at 0 o C as a function of elevation. Equation (3) was used to calculate barometric pressure. B) The effect of barometric pressure on apparent relative O concentration (O concentration measured with an O sensor). O sensors respond to absolute O concentration but are generally calibrated to yield relative O concentration. As the barometric pressure fluctuates, the absolute O concentration, and thus the O sensor output, fluctuates with it, producing an apparent change in the relative O concentration if the pressure effect is not accounted for. It is assumed the sensor was calibrated at 86.0 kpa. The solid line shows how the apparent relative O concentration is dependent on barometric pressure.

4 Effect of Temperature on Gas Concentration The ideal gas law (Eq. (1)) shows that absolute gas concentration decreases by % for a 1 C increase in temperature from 0 C (1 K / 93 K = ). For a sensor that measures absolute gas concentration but is calibrated to read out in relative units, a 1 C temperature increase from 0 C results in an apparent decrease of % O (0.341 % * = %) and a relative O concentration of %. As with barometric pressure, to obtain accurate O measurements a correction should be applied to compensate for temperature effects. The equation to correct O measurements in air for temperature effects is: ( T T ) M C O = + OM 1 (4) TC where O M is as given above, T C is the air temperature [K] at calibration, and T M is the air temperature [K] at the time of the measurement. The effects of temperature on relative O measurements, based on calculations from Eq. (4) are plotted (Fig. ) to show the significance of measuring and correcting for temperature. If not accounted for, temperature fluctuations show up in the measurement as an apparent change in relative O concentration because sensors respond to absolute O concentration but are calibrated to read relative O concentration. Sensor Response to Temperature In practice, Eq. (4) does not accurately correct for temperature effects because in addition to the ideal gas law temperature effect, sensor electronics are affected by temperature. The combination of these two effects on Apogee O sensors (soil and fast response sensors) was determined from measurements in dry air across a wide temperature range by plotting pressurecorrected apparent O concentration (i.e., measured O concentration before temperature correction was applied) versus sensor temperature (T S ) (Fig. ). Neither of the sensors follows the ideal gas law response (Fig. ), and thus an empirical correction derived from the measured data must be applied to account for both the ideal gas law and sensor electronics responses: O 3 OM + C3TS + C TS + C1T S + C0 = (5) where T S is the measured sensor temperature [ C] (Apogee O sensors come with a thermistor or type-k thermocouple temperature reference); the coefficients C 3, C, and C 1 are listed in Fig. for both the soil and fast-response sensors; and C 0 is the offset coefficient calculated from the temperature at calibration, T C [ C]: 3 1 ( C T + C T C T ) C = +. (6) 0 3 C C 1 C It is likely that the temperature effect on the sensor electronics varies from sensor to sensor, thus the coefficients derived herein (the average of the three sensors; error bars are shown in Fig. ) may not yield the most accurate temperature correction for all sensors of the same model.

5 Figure : Empirically-measured temperature responses of the soil and fast-response O sensors, with third order polynomials fit to the data points, compared to the theoretical temperature response calculated from the ideal gas law (Eq. (1)). The difference between the theoretical and measured responses is due to a temperature effect on the sensor electronics. The polynomial coefficients used to correct for the temperature response with Eq. (5) are listed. An offset coefficient (C 0 ) is not listed because it is dependent on the temperature at calibration. It is calculated with Eq. (6). The sensors were calibrated at 0 o C. As with barometric pressure, the absolute O concentration, and thus the O sensor output, varies with temperature. As temperature changes the relative O concentration remains constant at 0.95 %, but an apparent O change is measured if the temperature correction is not applied to relative measurements. Effect of Humidity on Gas Concentration As the humidity in the atmosphere increases, water vapor molecules displace and dilute other gas molecules, including O molecules. This causes the output of a sensor to decrease. The effect of water vapor displacement of O is larger at warmer temperatures because the capacity of air to hold water is greater and there is more water vapor in the air. The water vapor effect on relative O concentration as a function of relative humidity (RH) and at a constant temperature (Fig. 3A) is a linear decrease with increasing RH. Conversely, the effect as a function of temperature at constant RH is a curvilinear decrease with increasing temperature (Fig. 3B), essentially the inverse of the slope of the vapor pressure curves from the pyschrometric chart. Even though water vapor molecules dilute and diplace O molecules, and thus cause an actual and not an apparent decrease in relative O concentration, humidity effects are accounted for to yield relative O concentrations for a dry atmosphere. The equation to correct for humidity effects is:

6 e AM eac O = + OM 1 (7) BPC where BP C is as given above, e AM is the vapor pressure [kpa] of the air at the time of measurement, and e AC is the vapor pressure [kpa] of the air at calibration. The vapor pressures in Eq. (7) are calculated from: RH ea = es (8) 100 where RH is in % and e S is the saturation vapor pressure [kpa] of the air calculated from air temperature (T A ) [ C]: e S 17.50T A = exp. (9) TA In soil environments RH is generally always 100 %, unless the soil is extremely dry. Thus, the water vapor effect can be accounted for as a function of temperature by correcting O measurements based on the shape of the curve for 100 % RH. As with temperature, humidity also causes a slight effect on the sensor electronics. It is recommended that for measurements in soil or saturated air (RH = 100 %), the sensor be calibrated in conditions where the RH = 100 %. A simple way to accomplish this is to mount the sensor in a sealed chamber over water (Fig. 4).

7 Figure 3: A) Relative humidity (RH) effects on relative O concentration shown as a function of RH at temperatures increments of 10 C and B) as a function of temperature at RH increments of 0 %. The air in soil is generally always saturated with water vapor unless the soil is very dry.

8 Figure 4: Apogee O sensor mounted in a sealed chamber over water. For measurements in environments where the RH = 100 %, sensors should be calibrated in conditions where the RH = 100 % in order to account for any humidity effects on sensor electronics. Sensor Description and Calibration Apogee O sensors are galvanic cell sensors with a lead anode, gold cathode, acid electrolyte, and Teflon membrane (membrane where O diffusion occurs). The current flow between the two electrodes is linearly proportional to the absolute amount of O in the environment being measured. An internal bridge resistor is used to produce a voltage output rather than a direct current output. Galvanic cell sensors consume a small amount of gas in order to produce the current flow between the electrodes and subsequent voltage output. The O consumption from Apogee O sensors was measured to be.1 μmol per day at 0.95 % O and at an average temperature of 0 C in a small sealed chamber.

9 All sensors are equipped with an internal thermistor or type-k thermocouple for reference temperature measurement. The sensors also come equipped with a small resistance heater located behind the Teflon membrane inside the sensor. The heaters are designed to warm the sensor to a temperature slightly above ambient in order to keep condensation from occurring on the membrane under conditions where the RH is 100 %. The response time of the soil sensor is 60 seconds versus 14 seconds for the fast-response sensor (Fig. 5). The response time is defined as the time required for the sensor to read 90 % of the saturated response. Figure 5: Response times for both Apogee O sensor models (soil sensor and fast-response sensor). The response time is defined as the time required for the sensor to read 90 % of the saturated response (60 seconds for the soil sensor and 14 seconds for the fast-response sensor). The output signal for the soil sensor is approximately 58.0 mv under typical atmospheric conditions (0.95 % O and kpa) and the signal decrease is reported as 1.0 mv per year (<.0 % per year) (Fig. 6). The output signal for the fast-response sensor is approximately 1.8 mv under typical atmospheric conditions and the signal decrease is reported as 0.8 mv per year (6 % per year up to 5 years) (Fig. 6). The output of Apogee O sensors is a linear function of absolute O concentration. A simple linear calibration is generally used to derive a calibration factor used to convert the output from the sensor to relative O concentration. The calibration factor (CF) [% O / mv] is derived by simply dividing ambient O concentration (0.95 %) by the measured voltage output from the sensor under ambient conditions (in air or over water in a sealed chamber) minus the measured voltage output under conditions of 0 % O : 0.95% CF = mv mv (10) C 0

10 where mv C is the output [mv] of the sensor during calibration, mv 0 is the voltage output [mv] under 0 % O, and CF is a linear multiplier that converts subsequent voltage measurements from the sensor to % O using the equation: O = CF mv M Offset (11) where mv M is the measured output [mv] and Offset is derived by multiplying CF by mv 0. If mv 0 is not measured it can be assumed to be.5 mv for the soil sensor and 0.5 mv for the fastresponse sensor. It is recommend that mv 0 be measured (in pure N gas) for applications where low values of O (< 15 %) will be measured. Figure 6: Long-term stability (output voltage decrease over time) of both Apogee O sensor models (soil and fast response sensors). The response time and signal decrease are also listed for the two models.

### Absolute and Relative Gas Concentration: Understanding Oxygen in Air

Absolute and Relative Gas Concentration: Understanding Oxygen in Air Bruce Bugbee and Mark Blonquist The amount of oxygen (O 2 ) in air is described in two ways and it is essential to be able to convert

### Oxygen Sensor. SO-100 & 200 Series

Oxygen Sensor SO-100 & 200 Series www.apogeeinstruments.com techsupport@apogeeinstruments.com 435.792.4700 Fax: 435.787.8268 2 Theory of Operation The SO series are galvanic-cell type sensors that measure

### OWNER S MANUAL OXYGEN SENSOR. Models: SO-110, SO-120, SO-210, SO-220

OWNER S MANUAL OXYGEN SENSOR Models: SO-110, SO-120, SO-210, SO-220 APOGEE INSTRUMENTS, INC. 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA TEL: (435) 792-4700 FAX: (435) 787-8268 WEB: APOGEEINSTRUMENTS.COM

### CHAPTER 12. Gases and the Kinetic-Molecular Theory

CHAPTER 12 Gases and the Kinetic-Molecular Theory 1 Gases vs. Liquids & Solids Gases Weak interactions between molecules Molecules move rapidly Fast diffusion rates Low densities Easy to compress Liquids

### Major chemistry laws. Mole and Avogadro s number. Calculating concentrations.

Major chemistry laws. Mole and Avogadro s number. Calculating concentrations. Major chemistry laws Avogadro's Law Equal volumes of gases under identical temperature and pressure conditions will contain

### Physical and chemical properties of water Gas Laws Chemical Potential of Water Rainfall/Drought

Lecture 14, Water, Humidity, Pressure and Trace Gases, Part 1 Physical and chemical properties of water Gas Laws Chemical Potential of Water Rainfall/Drought Atmospheric Gas Composition constitue nt percent

### Operational Fuel Cell Voltage

Operational Fuel Cell Voltage Introduction From Chapter 2, the reversible OCV of a hydrogen fuel cell is given by the equation, E = g f zf When a fuel cell operates, the voltage is less than this. The

### Gas Laws. The kinetic theory of matter states that particles which make up all types of matter are in constant motion.

Name Period Gas Laws Kinetic energy is the energy of motion of molecules. Gas state of matter made up of tiny particles (atoms or molecules). Each atom or molecule is very far from other atoms or molecules.

### Work 1. Characterization of PEM fuel cell

Work 1. Characterization of PEM fuel cell Introduction Electrochemistry and electrochemical systems Electrochemistry can be defined as the science of structures and processes at and through the interface

### Effects of Temperature, Pressure and Water Vapor on Gas Phase Infrared Absorption by CO 2

Effects of Temperature, Pressure and Water Vapor on Gas Phase Infrared Absorption by CO 2 D. K. McDermitt, J. M. Welles, and R. D. Eckles - LI-COR, inc. Lincoln, NE 68504 USA Introduction Infrared analysis

### Designing with Labview

EE/CME 392 Laboratory 8-1 Designing with Labview Temperature Measurement with ADC controlled by Labview Safety: In this lab, voltages are less than 15 volts and this is not normally dangerous to humans.

### Use each of the terms below to complete the passage. Each term may be used more than once.

Gases Section 13.1 The Gas Laws In your textbook, read about the basic concepts of the three gas laws. Use each of the terms below to complete the passage. Each term may be used more than once. pressure

### TECHNICAL NOTES. = x100

TECHNICAL NOTES Humidity Humidity Measurement Controlling the environment indoors is the primary function of the HVAC industry. Humidity measurement is an important tool for predicting the climate outdoors

### = 1.038 atm. 760 mm Hg. = 0.989 atm. d. 767 torr = 767 mm Hg. = 1.01 atm

Chapter 13 Gases 1. Solids and liquids have essentially fixed volumes and are not able to be compressed easily. Gases have volumes that depend on their conditions, and can be compressed or expanded by

### Laboratory exercise No. 4 Water vapor and liquid moisture transport

Laboratory exercise No. 4 Water vapor and liquid moisture transport Water vapor transport in porous materials Due to the thermal conductivity of water and other unfavourable properties and effects in porous

### Thermodynamics of Mixing

Thermodynamics of Mixing Dependence of Gibbs energy on mixture composition is G = n A µ A + n B µ B and at constant T and p, systems tend towards a lower Gibbs energy The simplest example of mixing: What

### Vapor Pressure Lowering

Colligative Properties A colligative property is a property of a solution that depends on the concentration of solute particles, but not on their chemical identity. We will study 4 colligative properties

### 3-1 Copyright Richard M. Felder, Lisa G. Bullard, and Michael D. Dickey (2014)

EQUATIONS OF STATE FOR GASES Questions A gas enters a reactor at a rate of 255 SCMH. What does that mean? An orifice meter mounted in a process gas line indicates a flow rate of 24 ft 3 /min. The gas temperature

### Soil Suction. Total Suction

Soil Suction Total Suction Total soil suction is defined in terms of the free energy or the relative vapor pressure (relative humidity) of the soil moisture. Ψ = v RT ln v w 0ω v u v 0 ( u ) u = partial

### Chemistry 13: States of Matter

Chemistry 13: States of Matter Name: Period: Date: Chemistry Content Standard: Gases and Their Properties The kinetic molecular theory describes the motion of atoms and molecules and explains the properties

### The Gas Laws. Our Atmosphere. Pressure = Units of Pressure. Barometer. Chapter 10

Our Atmosphere The Gas Laws 99% N 2 and O 2 78% N 2 80 70 Nitrogen Chapter 10 21% O 2 1% CO 2 and the Noble Gases 60 50 40 Oxygen 30 20 10 0 Gas Carbon dioxide and Noble Gases Pressure Pressure = Force

### CHEMISTRY. Matter and Change. Section 13.1 Section 13.2 Section 13.3. The Gas Laws The Ideal Gas Law Gas Stoichiometry

CHEMISTRY Matter and Change 13 Table Of Contents Chapter 13: Gases Section 13.1 Section 13.2 Section 13.3 The Gas Laws The Ideal Gas Law Gas Stoichiometry State the relationships among pressure, temperature,

### EXPERIMENT 15: Ideal Gas Law: Molecular Weight of a Vapor

EXPERIMENT 15: Ideal Gas Law: Molecular Weight of a Vapor Purpose: In this experiment you will use the ideal gas law to calculate the molecular weight of a volatile liquid compound by measuring the mass,

### Vapor-Liquid Equilibria

31 Introduction to Chemical Engineering Calculations Lecture 7. Vapor-Liquid Equilibria Vapor and Gas Vapor A substance that is below its critical temperature. Gas A substance that is above its critical

### Abbreviations Conversions Standard Conditions Boyle s Law

Gas Law Problems Abbreviations Conversions atm - atmosphere K = C + 273 mmhg - millimeters of mercury 1 cm 3 (cubic centimeter) = 1 ml (milliliter) torr - another name for mmhg 1 dm 3 (cubic decimeter)

### Tutorial 6 GASES. PRESSURE: atmospheres or mm Hg; 1 atm = 760 mm Hg. STP: Standard Temperature and Pressure: 273 K and 1 atm (or 760 mm Hg)

T-41 Tutorial 6 GASES Before working with gases some definitions are needed: PRESSURE: atmospheres or mm Hg; 1 atm = 760 mm Hg TEMPERATURE: Kelvin, K, which is o C + 273 STP: Standard Temperature and Pressure:

### General Properties of Gases. Properties of Gases. K is for Kelvin. C is for degrees Celsius. F is for degrees Fahrenheit PROPERTIES OF GASES GAS LAWS

PROPERTIES OF GASES or GAS LAWS 1 General Properties of Gases There is a lot of empty space in a gas. Gases can be expanded infinitely. Gases fill containers uniformly and completely. Gases diffuse and

### Lecture 10 Humidity Sensing and Flow Sensing. EE 4900 Fundamentals of Sensor Design

EE 4900: Fundamentals of Sensor Design Lecture 10 Humidity Sensing and Flow Sensing 1 2 Humidity Sensing Humidity Sensing Q: What are we measuring? A: Water vapor content in air and other gases. 3 Usually

### Chemistry, The Central Science, 11th edition Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten. Chapter 10 Gases

Chemistry, The Central Science, 11th edition Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten Chapter 10 Gases A Gas Has neither a definite volume nor shape. Uniformly fills any container.

### Determining Equivalent Weight by Copper Electrolysis

Purpose The purpose of this experiment is to determine the equivalent mass of copper based on change in the mass of a copper electrode and the volume of hydrogen gas generated during an electrolysis reaction.

### THE HUMIDITY/MOISTURE HANDBOOK

THE HUMIDITY/MOISTURE HANDBOOK Table of Contents Introduction... 3 Relative Humidity... 3 Partial Pressure... 4 Saturation Pressure (Ps)... 5 Other Absolute Moisture Scales... 8 % Moisture by Volume (%M

### Chapter 4 The Properties of Gases

Chapter 4 The Properties of Gases Significant Figure Convention At least one extra significant figure is displayed in all intermediate calculations. The final answer is expressed with the correct number

### Humidity, Evaporation, and

Humidity, Evaporation, and Boiling Bởi: OpenStaxCollege Dew drops like these, on a banana leaf photographed just after sunrise, form when the air temperature drops to or below the dew point. At the dew

### Simple Mixtures. Atkins 7th: Sections ; Atkins 8th: The Properties of Solutions. Liquid Mixtures

The Properties of Solutions Simple Mixtures Atkins 7th: Sections 7.4-7.5; Atkins 8th: 5.4-5.5 Liquid Mixtures Colligative Properties Boiling point elevation Freezing point depression Solubility Osmosis

### N 2 C balance: 3a = = 9.2 a = H CO = CO H 2. theo. A-F ratio =

15.26 Liquid propane is burned with dry air. A volumetric analysis of the products of combustion yields the following volume percent composition on a dry basis: 8.6% CO 2, 0.6% CO, 7.2% O 2 and 83.6% N

### Gas Laws. E k = ½ (mass)(speed) 2. v101613_10am

Gas Laws v101613_10am Objective: In this lab you will become familiar with the Ideal Gas Law and Dalton s Law of Partial Pressures. You will be able to use the information collected along with stoichiometry

### Physics Courseware Physics I Ideal Gases

Physics Courseware Physics I Ideal Gases Problem 1.- How much mass of helium is contained in a 0.0 L cylinder at a pressure of.0 atm and a temperature of.0 C? [The atomic mass of helium is 4 amu] PV (

### Determining Equivalent Weight by Copper Electrolysis

Purpose To determine the equivalent mass of copper based on change in the mass of a copper electrode and the volume of hydrogen gas generated during an electrolysis experiment. The volume of hydrogen gas

### How Sensors Work. How Oxygen, Electrochemical Toxic, and Metal Oxide Semiconductor Sensors Work *

How Oxygen, Electrochemical Toxic, and Metal Oxide Semiconductor Sensors Work * 1. Oxygen sensor detection principle Most portable or survey instruments used for workplace evaluation of oxygen concentrations

### Colligative properties of biological liquids

Colligative properties of biological liquids Colligative properties are properties of solutions that depend on the number of molecules in a given volume of solvent and not on the properties (e.g. size

### Thermodynamics and Kinetics. Lecture 14 Properties of Mixtures Raoult s Law Henry s Law Activity NC State University

Thermodynamics and Kinetics Lecture 14 Properties of Mixtures Raoult s Law Henry s Law Activity NC State University Measures of concentration There are three measures of concentration: molar concentration

### Chapter 5. Name: Class: Date: Multiple Choice Identify the choice that best completes the statement or answers the question.

Class: Date: Chapter 5 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. What is the pressure of the sample of gas trapped in the open-tube mercury manometer

### HM1500LF Relative Humidity Module

Small size product Product free from Lead, Cr(6+), Cd and Hg Humidity calibrated within +/-2% @55%RH Typical 1 to 3.6 Volt DC output for 0 to 100% RH at 5Vdc supply Ratiometric to voltage supply from 4.75Vdc

### Weather Basics. Temperature Pressure Wind Humidity. Climate vs. Weather. Atmosphere and Weather

Climate vs. Weather Atmosphere and Weather Weather The physical condition of the atmosphere (moisture, temperature, pressure, wind) Climate Long term pattern of the weather in a particular area Weather

### MECE 3320 Measurements and Instrumentation Lab Lab - 6: Dynamic Response of Temperature Measuring Devices

MECE 33 Measurements and Instrumentation Lab Lab - 6: Dynamic esponse of emperature Measuring Devices. Introduction hermocouples When a pair of electrical conductors (metals) are joined together, a thermal

### HTM2500 Temperature and Relative Humidity Module

Hermetic Housing Humidity calibrated within +/-2% @55%RH Temperature measurement through NTC 10kOohms +/- 3% direct output Small size product Typical 1 to 4 Volt DC output for 0 to 100%RH at 5Vdc DESCRIPTION

### Reading Assignment: A&B: Ch. 5 (p. 123-134) CD: Tutorials 3 & 4 (Atm. Moisture; Adiab. Proc.) Interactive Ex.: Moisture LM: Lab# 7

G109: 7. Moisture 1 7. MOISTURE Reading Assignment: A&B: Ch. 5 (p. 123-134) CD: Tutorials 3 & 4 (Atm. Moisture; Adiab. Proc.) Interactive Ex.: Moisture LM: Lab# 7 1. Introduction Moisture in the atmosphere:

### Dynamic accumulation method for measuring oxygen transmission rate of food packaging materials using florescence oxygen detection

Dynamic accumulation method for measuring oxygen transmission rate of food packaging materials using florescence oxygen detection Bruce Welt a, Ayman Abdellatief b a University of Florida, Gainesville,

### How to measure absolute pressure using piezoresistive sensing elements

In sensor technology several different methods are used to measure pressure. It is usually differentiated between the measurement of relative, differential, and absolute pressure. The following article

### Chapter 14. Mixtures

Chapter 14 Mixtures Warm Up What is the difference between a heterogeneous and homogeneous mixture? Give 1 example of a heterogeneous mixture and 1 example of a homogeneous mixture. Today s Agenda QOTD:

### Chapter 5 Practise Test

Chapter 5 Practise Test 1. An open end mercury manometer was constructed from a U shaped tube. In a particular measurement, the level in the end connected to the gas manifold, on which the experiment was

### The Gas, Liquid, and Solid Phase

The Gas, Liquid, and Solid Phase When are interparticle forces important? Ron Robertson Kinetic Theory A. Principles Matter is composed of particles in constant, random, motion Particles collide elastically

### Measure Humidity - Basics

Dalton s Law Air is a mixture of different gases. Under normal environmental conditions the gases have an ideal behaviour, i.e. each gas molecule can act independently from all others. Dalton s law is

### Figure 10.3 A mercury manometer. This device is sometimes employed in the laboratory to measure gas pressures near atmospheric pressure.

Characteristics of Gases Practice Problems A. Section 10.2 Pressure Pressure Conversions: 1 ATM = 101.3 kpa = 760 mm Hg (torr) SAMPLE EXERCISE 10.1 Converting Units of Pressure (a) Convert 0.357 atm to

### HAST (Highly Accelerated Stress Test)

HAST (Highly Accelerated Stress Test) Definition and Test Standards HAST The highly accelerated temperature and humidity stress test (HAST) is a highly accelerated method of electronic component reliability

### Exploring Gas Laws. Chapter 12. Solutions for Practice Problems. Student Textbook page 477

Chapter 12 Exploring Gas Laws Solutions for Practice Problems Student Textbook page 477 1. Problem At 19 C and 100 kpa, 0.021 mol of oxygen gas, O 2(g), occupy a volume of 0.50 L. What is the molar volume

### + MT] Liquid-Expansion Thermometers Solid-State Temperature Sensors THERMAL SENSORS 1199

THERMAL SENSORS 1199 4.6.4 Liquid-Expansion Thermometers Just as a solid experiences an expansion in dimension with temperature. a liquid also shows an expansion in volume with temperature. This effect

### Temperature. Number of moles. Constant Terms. Pressure. Answers Additional Questions 12.1

Answers Additional Questions 12.1 1. A gas collected over water has a total pressure equal to the pressure of the dry gas plus the pressure of the water vapor. If the partial pressure of water at 25.0

### Sample Exercise 10.1 Converting Pressure Units

Sample Exercise 10.1 Converting Pressure Units (a) Convert 0.357 atm to torr. (b) Convert 6.6 10 2 torr to atmospheres. (c) Convert 147.2 kpa to torr. Solution Analyze In each case we are given the pressure

### Proton Exchange Membrane Fuel Cells (PEMFCs)

Proton Exchange Membrane Fuel Cells (PEMFCs) Docent Jinliang Yuan November, 2008 Department of Energy Sciences Lund Institute of Technology (LTH), Sweden Four PEMFC stacks illustrating developments through

### Vapor Pressure Diagrams and Boiling Diagrams

Vapor Pressure Diagrams and Boiling Diagrams We are now ready to begin talking about phase diagrams involving two components. Our first few phase diagrams will involve only the liquid and gas (or vapor)

### Chapter 17 Temperature, Thermal Expansion, and the Ideal Gas Law. Copyright 2009 Pearson Education, Inc.

Chapter 17 Temperature, Thermal Expansion, and the Ideal Gas Law Units of Chapter 17 Atomic Theory of Matter Temperature and Thermometers Thermal Equilibrium and the Zeroth Law of Thermodynamics Thermal

### Gas Thermometer and Absolute Zero

Chapter 1 Gas Thermometer and Absolute Zero Name: Lab Partner: Section: 1.1 Purpose Construct a temperature scale and determine absolute zero temperature (the temperature at which molecular motion ceases).

### Applied Thermodynamics for Marine Systems Prof. P. K. Das Department of Mechanical Engineering Indian Institute of Technology, Kharagpur

Applied Thermodynamics for Marine Systems Prof. P. K. Das Department of Mechanical Engineering Indian Institute of Technology, Kharagpur Lecture - 7 Ideal Gas Laws, Different Processes Let us continue

### 6 Evaluation of the Gas Law Constant

6 Evaluation of the Gas Law Constant Name: Date: Section: Objectives Measure the value of the gas constant R Use Dalton s Law to calculate the partial pressure of hydrogen in a closed container Learn to

### 2. If pressure is constant, the relationship between temperature and volume is a. direct b. Inverse

Name Unit 11 Review: Gas Laws and Intermolecular Forces Date Block 1. If temperature is constant, the relationship between pressure and volume is a. direct b. inverse 2. If pressure is constant, the relationship

### MOLECULAR WEIGHT BY BOILING POINT ELEVATION

MOLECULAR WEIGHT BY BOILING POINT ELEVATION BACKGROUND This experiment demonstrates the use of colligative properties. The goal is to measure the molecular weight of a non-volatile solute by determining

### Boyle s law PV = K. (at a constant temperature) Definition of terms used. Units. Explanation. Clinical application/worked example

Boyle s law PV = K Or Vµ 1 P (at a constant temperature) Definition of terms used P = pressure V = volume K = constant Units None. Explanation Boyle s law (Robert Boyle, 1662) describes one of the characteristics

### Calculations involving concentrations, stoichiometry

Calculations involving concentrations, stoichiometry MUDr. Jan Pláteník, PhD Mole Unit of amount of substance the amount of substance containing as many particles (atoms, ions, molecules, etc.) as present

### PROPERTIES OF PURE SUBSTANCES

Thermodynamics: An Engineering Approach Seventh Edition in SI Units Yunus A. Cengel, Michael A. Boles McGraw-Hill, 2011 Chapter 3 PROPERTIES OF PURE SUBSTANCES Mehmet Kanoglu University of Gaziantep Copyright

### Worldwide Manufacturer of Gas Detection Solutions. O 2 Transmitter ZD 21. Operation Manual

Worldwide Manufacturer of Gas Detection Solutions O 2 Transmitter ZD 21 Operation Manual Table of Contents For your safety...4 General description...4 Detection principle...5 Operational notes...5 Design...5

### V. Water Vapour in Air

V. Water Vapour in Air V. Water Vapour in Air So far we have indicated the presence of water vapour in the air through the vapour pressure e that it exerts. V. Water Vapour in Air So far we have indicated

### Chapter 13 Gases. An Introduction to Chemistry by Mark Bishop

Chapter 13 Gases An Introduction to Chemistry by Mark Bishop Chapter Map Gas Gas Model Gases are composed of tiny, widely-spaced particles. For a typical gas, the average distance between particles is

### Lecture Notes: Gas Laws and Kinetic Molecular Theory (KMT).

CHEM110 Week 9 Notes (Gas Laws) Page 1 of 7 Lecture Notes: Gas Laws and Kinetic Molecular Theory (KMT). Gases Are mostly empty space Occupy containers uniformly and completely Expand infinitely Diffuse

### Which Temperature Sensor To Choose From, Thermistor, Resistance Temperature Detector (RTD) or Thermocouple?

Which Temperature Sensor To Choose From, Thermistor, Resistance Temperature Detector (RTD) or Thermocouple? The concept of temperature From a physical point of view, heat is a measure of the energy contained

### Welcome Vaisala Industrial Measurement Webinar Series - Dew point in Compressed Air

Welcome Vaisala Industrial Measurement Webinar Series - Dew point in Compressed Air Dew point is an excellent parameter to measure in a compressed air line Yumi Alanoly Vaisala Application Engineer Agenda

### Chemistry 212 VAPOR PRESSURE OF WATER LEARNING OBJECTIVES

Chemistry 212 VAPOR PRESSURE OF WATER LEARNING OBJECTIVES The learning objectives of this experiment are to explore the relationship between the temperature and vapor pressure of water. determine the molar

### Reaction Engineering of Polymer Electrolyte Membrane Fuel Cells

Reaction Engineering of Polymer Electrolyte Membrane Fuel Cells A new approach to elucidate the operation and control of Polymer Electrolyte Membrane (PEM) fuel cells is being developed. A global reactor

### Chapter 3 Properties of A Pure Substance

Chapter 3 Properties of A Pure Substance Pure substance: A pure substance is one that has a homogeneous and invariable chemical composition. Air is a mixture of several gases, but it is considered to be

### Pressure Transmitter Training Fundamentals of Pressure Measurement

Pressure Transmitter Training Fundamentals of Pressure Measurement Topics To Be Covered Pressure Measurement Absolute, Gauge, & Differential Pressure Pressure Transmitters Basic Functions Transmitter Terminology

### AP CHEMISTRY 2009 SCORING GUIDELINES (Form B)

AP CHEMISTRY 2009 SCORING GUIDELINES (Form B) Question 3 (10 points) 2 H 2 O 2 (aq) 2 H 2 O(l) + O 2 (g) The mass of an aqueous solution of H 2 O 2 is 6.951 g. The H 2 O 2 in the solution decomposes completely

### Experiment 12E LIQUID-VAPOR EQUILIBRIUM OF WATER 1

Experiment 12E LIQUID-VAPOR EQUILIBRIUM OF WATER 1 FV 6/26/13 MATERIALS: PURPOSE: 1000 ml tall-form beaker, 10 ml graduated cylinder, -10 to 110 o C thermometer, thermometer clamp, plastic pipet, long

### Course 2 Mathematical Tools and Unit Conversion Used in Thermodynamic Problem Solving

Course Mathematical Tools and Unit Conversion Used in Thermodynamic Problem Solving 1 Basic Algebra Computations 1st degree equations - =0 Collect numerical values on one side and unknown to the otherside

### HTS2030SMD Temperature and Relative Humidity Sensor

Miniature Surface mount SMD package Lead free component Patented solid polymer structure Suitable for linear voltage or frequency output circuitry Fast response time and very low temperature coefficient

### Reservoir Fluids PETE 310

Reservoir Fluids PETE 31 Lab 2: Determination of the Vapor Pressure of Propane Learning Objectives When you complete this laboratory, you should be able to: Use closed-cell and sight-glass methods for

### Designing interface electronics for zirconium dioxide oxygen sensors of the XYA series

1 CIRCUIT DESIGN If not using one of First Sensors ZBXYA interface boards for sensor control and conditioning, this section describes the basic building blocks required to create an interface circuit Before

### HTM2500LF Temperature and Relative Humidity Module

Hermetic Housing Humidity calibrated within +/-2% @55%RH Temperature measurement through NTC 10kOhms +/-1% direct output Small size product Typical 1 to 4 Volt DC output for 0 to 100%RH at 5Vdc DESCRIPTION

### User Guide. 9708 Dissolved Oxygen Probes

User Guide 9708 Dissolved Oxygen Probes Introduction The Thermo Scientific Orion 9708 dissolved oxygen probe simplifies measurements of dissolved oxygen, particularly Biochemical Oxygen Demand (BOD).

### AP Chemistry ( MCSEMENICK2015 ) My Courses Course Settings Chemistry: The Central Science, 12e Brown/LeMay/Bursten/Murphy/Woodward

Signed in as Daniel Semenick, Instructor Help Sign Out AP Chemistry ( MCSEMENICK2015 ) My Courses Course Settings Chemistry: The Central Science, 12e Brown/LeMay/Bursten/Murphy/Woodward Instructor Resources

### Gases. Macroscopic Properties. Petrucci, Harwood and Herring: Chapter 6

Gases Petrucci, Harwood and Herring: Chapter 6 CHEM 1000A 3.0 Gases 1 We will be looking at Macroscopic and Microscopic properties: Macroscopic Properties of bulk gases Observable Pressure, volume, mass,

### 5. Which temperature is equal to +20 K? 1) 253ºC 2) 293ºC 3) 253 C 4) 293 C

1. The average kinetic energy of water molecules increases when 1) H 2 O(s) changes to H 2 O( ) at 0ºC 3) H 2 O( ) at 10ºC changes to H 2 O( ) at 20ºC 2) H 2 O( ) changes to H 2 O(s) at 0ºC 4) H 2 O( )

### Wed Sep 12, 2007 THE GASEOUS STATE

Chapter 5: Gases Gas Stoichiometry Partial Pressure Kinetic Theory Effusion and Diffusion Wed Sep 12, 2007 Exam #1 - Friday, Sep 14 Attendance is mandatory! Practice exam today in recitation Week 3 CHEM

### Oxygen-Transfer Measurement in Clean Water

Oxygen-Transfer Measurement in Clean Water Zhen He*, Anurak Petiraksakul** and Warawitya Meesapya** Abstract This paper presents the experiments on measurement of oxygen transfer capacity in clean water

### Chemical Process calculation III

Chapter 7 Ideal and Real Gases Gas, Liquid, and Solid Chemical Process calculation III Gas: a substance in a form like air, relatively low in density and viscosity Liquid: a substance that flows freely

### EXP #3: TEMPERATURE TRANSDUCERS

EXP #3: TEMPERATURE TRANSDUCERS I. INTRODUCTION Objectives: To understand the operation of thermistors and realization of a temperature sensing device, to study the basic characteristics of an I.C. temperature

### Saturation Vapour Pressure above a Solution Droplet

Appendix C Saturation Vapour Pressure above a Solution Droplet In this appendix, the Köhler equation is derived. As in Appendix B, the theory summarised here can be found in Pruppacher & Klett (1980) and

### Colligative Properties. Vapour pressure Boiling point Freezing point Osmotic pressure

Colligative Properties Vapour pressure Boiling point Freezing point Osmotic pressure Learning objectives Describe meaning of colligative property Use Raoult s law to determine vapor pressure of solutions