CP Chemistry Review sheet for Test on Chapter 13: The Gas Laws. Practice Problems for Gas Laws

Transcription

1 CP Chemistry Review sheet for Test on Chapter 13: The Gas Laws 13.1 The Gas Laws Boyles Law Charles s Law Gay-Lussac s Law Combined Gas Law 13.2 The Ideal Gas Law Ideal Gas Law R = L*atm/mol*K Practice Problems for Gas Laws The hardest thing about these chapters is knowing when to use which formula, so these problems are not in the order we learned them. Ask yourself these questions to see when we need to use which formula 1. Are the properties of the gas changing? Yes: What is changing? Volume and Pressure: Boyle s Law Volume and Temperature: Charles Law Pressure and Temperature: Gay-Lussac s Law All three: Combined Gas Law 2. Is the question looking for pressure, temperature, moles, volume or molar mass? Yes: Use Ideal Gas Law 1

2 Practice Problems for Gas Laws Boyle s Law: P 1 V 1 = P 2 V 2 Charles s Law: V 1 /T 1 = V 2 /T 2 Gay-Lussac s Law: P 1 /T 1 = P 2 /T 2 Combined Gas Law: P 1 V 1 /T 1 = P 2 V 2 /T 2 Ideal Gas Law: PV=nRT R =.0821L*atm/mol*K TEMPERATURE MUST BE IN KELVIN: o C Remember: 1. Pick your formula 2. Plug in values (including units) 3. Use algebra to solve 4. Make sure you answer has correct significant figures and units. Problems: 1. A bottle containing only air is sealed at a temperature of 22 o C and a pressure of atm. The bottle is placed in a freezer and allowed to cool to -3 o C. What is the pressure in the bottle? 2. A cylinder of compressed gas has a pressure of atm on one day. The next day, the same cylinder of gas has a pressure of atm, and its temperature is 8 o C. What was the temperature of the previous day is o C? 2

3 3. A child received a balloon filled with 2.30 L of helium from a vendor at an amusement park where the temperature is 311 K. What will be the volume of the balloon be when the child brings the balloon home to an air-conditioned house at 295 K? 4. A weather balloon has a maximum volume of L. The balloon contains 195 L of helium gas at a pressure of atm. What will be the pressure when the balloon is at maximum volume? 5. The safety limit for a certain can of aerosol spray is 95 o C. If the pressure of the gas in the can is 2.96 atm when it is 17 o C, what will the pressure be at the safety limit? 6. A sample of helium has a volume of 500. ml at STP ( kpa and 273K). What will be its new volume if the temperature is increased to 325 K and its pressure is increased to 125 kpa. 7. A sample of gas has a pressure of atm and 62.0 ml at a temperature of 373 K. To what temperature does the gas have to be adjusted in order to achieve a pressure of atm and a volume 64.0 ml? 3

4 8. What volume, in ml will mol of hydrogen gas occupy at a pressure of atm and a temperature of 9 o C? 9. How many moles of oxygen gas must be in a 10.0 L container to exert a pressure of.844 atm at a temperature of 25 o C? 10. A large balloon contains 11.7 g of helium. What volume will the helium occupy at an higher altitude, where the atmospheric pressure atm and the temperature is -50 o C? 11. What is the molar mass of a gas if a 15.0 g sample has a pressure of 1.26 atm and a volume of 43.4 L at 30.0 o C? 4

5 #TBTs!!! 1. What is the difference between the independent and dependent variable? 2. How many significant figures does a number have? (example:.00670) 3. Calculations with correct significant figures (example: 2.65 x.035) 4. Converting one metric unit to another metric unit (keeping in mind significant figures - example: ml to L) 5. Is a change a chemical or physical change? (example: snow melting, iron rusting,...) 6. Percent by mass problems (example: what is the percent of oxygen in a compound that contains 12.6 g of oxygen and 46.3 g of nitrogen, and 5.67 g of hydrogen. 7. Number of neutrons, protons, and electrons mass number and atomic number. (example: How many p +, n, and e - does the atom 40 19K have?) 8. Writing electron configurations(example: Mg 1s 2, 2s 2, 2p 6, 3s 2 ) 9. Writing orbital diagrams (example: 1s 2s 2p 3s 10. Groups of the periodic table (example: what group does silver belong to?) 11. Stating the number of valence electrons (example: how many valence electrons does silicon have?) 12. Writing the name for ionic compounds (example: Pb(NO 3 ) 2 ) 13. Writing the formula for ionic compounds (example: Iron (II) hydroxide) 14. What is the Lewis dot structure for a molecule (example: NH 3 ) 15. Is a molecule polar or non polar (example: NH 3 ) 16. What type of reaction is listed (example: CaO (s) + CO 2 (g) CaCO 3 (s)) 17. Balance a chemical equation (example: silver nitrate (aq) + sodium sulfide (aq) silver sulfide (s) + sodium nitrate (aq)) 18. Converting between grams, molecules, atoms, formula units, and liters of gas at STP ( how may moles are grams of (NH 4 ) 2 SO 3 ) 19. Converting between grams, molecules, atoms, formula units, and liters of gas at STP (example: what is the mass of 6.42 Í molecules of water?) 20. Stoichiometry problems (example: given the following balanced chemical equation, 2H 2 (g) + O 2 (g) 2H 2 O (g), how many grams of water can be produced from 948 L of O 2 gas at STP?) 5

6 21. Percent yield problems (example: given the following balanced chemical equation, 2H 2 (g) + O 2 (g) 2H 2 O (g), what is the percent yield of H 2 O if the reaction of 64.9 grams of H 2 produces 510. grams of H 2 O?) 6