Tuesday, November 27, 2012 Expectations:

Transcription

1 Tuesday, November 27, 2012 Expectations: Sit in assigned seat Get out Folder, Notebook, Periodic Table Have out: Spiral (notes), Learning Target Log (new) No Backpacks on tables Listen/Pay Attention Learning Target: IWBAT (a) explain the Principle of Conservation of Mass, (b) define a mole, (c) calculate molar mass. Focus: Balance the following equation: CO(g) + H 2 (g) C 8 H 18 (l) + H 2 O(g) Makeup Tests during Lunch!

2 Conservation of Mass Lab You have about 30 minutes! Work in Pairs! If you make a mess, clean it up! At end of lab, I will see on each table: Clean tables, dry, no trash 2 large clean dry beakers 2 small clean, dry beakers Mass of clean dry beakers FIRST, before any ingredients. Exactly 100 ml of vinegar (acid) is not important, only the mass. Exactly 10g of baking soda is not important, only the mass Mix SLOWLY. If you overflow, you have to start over.

3 Wednesday, November 28, 2012 Expectations: Sit in assigned seat Have out: Folder, Notebook, Periodic Table No Backpacks on tables Listen/Pay Attention Learning Target: IWBAT (a) define a mole, (b) calculate molar mass, (c) convert from mass to moles and moles to mass. Focus: Balance the following equation: Al + HCl AlCl3 + H2 Makeup Tests during Lunch!

4 How Big is a Mole? THE MOLE

5 How do we measure the mass of something so small? Can you measure the thickness of a piece of paper with a ruler? Can you measure the mass of a crystal of sugar? How do we do it? We measure the mass or amount based on a large quantity. Same for atoms

6 The Mole What is a MOLE? A unit of measure, similar to dozen. A very large number A MOLE is 6.02x10 23 of anything What is a MOLE used for? The MOLE is used to measure the mass of a large quantity of atoms A Mole of atoms weighs the atomic mass (in grams) on the periodic table. 1 mole of Helium weighs 4.04 grams 1 mole of carbon weighs grams

7 Molar Mass/Formula Mass What is molar mass? mass of one mole of atoms for the same element Use Atomic Mass from periodic table, labeled as GRAMS What is formula mass? Mass of one mole of a compound Chemical formula tells you the mass One mole of the compound contains one mole of each element in the proportions listed.

8 FORMULA MASS Examples: Molar Mass Molar mass of carbon is grams Molar mass of iron (Fe) is 55.8 grams Example: Salt (NaCl) Examples: Formula Mass 1 atom sodium (Na), mass g/mole 1 atom chlorine (Cl), mass g/mole Formula mass is 1(22.99) + 1(35.45) = g NaCl/mole NaCl

9 FORMULA MASS Example: Water (H 2 O) 2 atoms hydrogen (H), mass 1.01 g/mole 1 atom oxygen (O), mass g/mole Formula mass is 2(1.01) + 1(16.00) = g/mole Example: Glucose (C 6 H 12 O 6 ) 6 atoms carbon (C), mass g/mole 12 atoms hydrogen (H), 1.01 g/mole 6 atoms oxygen (O), g/mole Formula mass: 6(12.01) + 12(1.01) + 6(16.00) = g/mole

10 Formula Mass Polyatomic Groups have parentheses around them Are treated like an atom Number outside the parenthesis is how many groups there are. Formula mass multiplies the mass of the group by the number outside the parenthesis Example: Ca(OH) 2 one atom Calcium (Ca) 2 groups of one oxygen (O) and one hydrogen (H) = 2 oxygen atoms and 2 hydrogen atoms

11 Calculate the Following: Find Molar Mass for: Carbon Silver Nickel Gold Lead (Pb) Calculate Formula Mass for: ZnCl 2 K 3 PO 4 NiSO 3 Fe(NO 3 ) 3 Co(ClO 3 ) 2

12 Thursday, November 29, 2012 Expectations: Sit in assigned seat Have out: Folder, Notebook, Periodic Table No Backpacks on tables Listen/Pay Attention Learning Target: IWBAT (a) convert from mass (grams) to moles and moles to mass (grams). Focus: Balance the following equation: H3PO4 + HCl PCl5 + H2O Makeup Tests during Lunch!

13 When the equation Fe 3 O 4 + Al Al 2 O 3 + Fe is correctly balanced, what is the coefficient of Fe? A)3 B)4 C)6 D)9

14 How to convert from grams to moles to grams MOLE/MASS CONVERSIONS

15 The Mole Hill

16 NOTES! Copy these conversions. 1 mole = x atoms 1 mole = molecular weight (in grams)

17 Lets try one together! Determine the mass in grams of 5.50 moles if iron. Put the original number over 1. Decide where the unit needs to go in the next step to cancel out. Decide which conversion you will use, and plug in the numbers.

18 The Answer 5.50 mol Fe g Fe 1 mol Fe = 307 g Fe Always start with what you are given (5.50 mol) Put it over 1 (place holder only) Use the dimension that cancels the starting units We started with moles, so moles on bottom Multiply on top. Divide on bottom Answer is units that are left over (grams)

19 Determine the amount of iron present in 352 grams of Fe.

20 The Answer 352 grams Fe x 1 mole Fe = 6.30 mols Fe grams

21 Mass to Moles Conversions Use Dimensional Analysis: Formula mass is: 1 mole = x grams. Example: How many moles are in 25 grams of HF? Find formula mass first: 1(H) + 1(F) = 1(1.01) + 1(19) = 20.01g HF/1 mole HF LABELS ARE IMPORTANT HERE 25 g HF x 1 mole HF = 1.25 mole HF g HF Dimension

22 Moles to Mass Conversion Example How many moles are in 1.1 grams of FeCl 3 Calculate formula weight: 1(Fe) + 3(Cl) = (35.45) = g FeCl 3 /1 mole FeCl 3 Set Up Dimensional Analysis Problem: 1.1 g FeCl 3 x 1mole FeCl 3 =.0068 mole FeCl g FeCl 3

23 Moles to Mass Conversion How many grams are in 5.6 moles of C 6 H 6? Calculate formula mass: 6(C) + 6(H) = 6(12) + 6(1) = 78 g/1mole C 6 H 6 Set Up Dimensional Analysis: 5.6 mole C 6 H 6 x 78g C 6 H 6 = g C 6 H 6 1 mole C 6 H 6

24 Your Turn Complete Even Number Problems on Mole/Mass Conversions Worksheet

25 Friday, November 30, 2012 Expectations: Sit in assigned seat Have out: Folder, Notebook, Periodic Table, writing device No Backpacks on tables Listen/Pay Attention Learning Target: IWBAT (a) convert from particles (atoms or molecules) to moles and moles to particles (atoms or molecules). Focus: Balance the following equation: Rb + RbNO 3 => Rb 2 O + N 2 Turn in Today: Molar Mass, Grams/Moles

26 Quiz 11/30/12 Which coefficients correctly balance the formula equation CaO + H 2 O Ca(OH) 2? a. 2, 1, 2 c. 1, 2, 1 b. 1, 2, 3 d. 1, 1, 1 What is the balanced equation for the combustion of sulfur? a. S(s) + O 2 (g) SO(g) c. 2S(s) + 3O 2 (g) SO 3 (s) b. S(s) + O 2 (g) SO 2 (g) d. S(s) + 2O 2 (g) SO 2 4 (aq)

27 Avogadro s Number (6.02 x ) MOLES TO ATOMS CONVERSIONS

28 The Mole Hill

29 Avogadro s Number as Conversion Factor 6.02 x particles 1 mole or 1 mole 6.02 x particles Note that a particle could be an atom OR a molecule!

30 A Mole of Particles Contains 6.02 x particles 1 mole C 1 mole H 2 O 1 mole NaCl = 6.02 x C atoms = 6.02 x H 2 O molecules = 6.02 x NaCl molecules (technically, ionics are compounds not molecules so they are called formula units) 6.02 x Na + ions and 6.02 x Cl ions

31 B. Converting Moles to Particles Suppose you want to determine how many particles of sucrose are in 3.50 moles of sucrose. You know that one mole contains 6.02 x representative particles. Therefore, you can write a conversion factor, Avogadro s number, that relates representative particles to moles of a substance.

32 B. Converting Moles to Particles You can find the number of representative particles in a number of moles just as you found the number of roses in 3.5 dozen. For sucrose, the representative particle is a molecule, so the number of molecules of sucrose is obtained by multiplying 3.50 moles of sucrose by the conversion factor, Avogadro s number.

33 B. Converting Moles to Particles There are 2.11 x molecules of sucrose in 3.50 moles.

34 B. Converting Particles to Moles Now, suppose you want to find out how many moles are represented by a certain number of representative particles. You can use the inverse of Avogadro s number as a conversion factor.

35 Example: B. Converting Particles to Moles Zinc is used as a corrosion-resistant coating on iron and steel. It is also an essential trace element in your diet. Calculate the number of moles that contain 4.50 x atoms of zinc (Zn).

36 B. Converting Particles to Moles Multiply the number of zinc atoms by the conversion factor that is the inverse of Avogadro s number. 4.50x10 24 atoms Zn X 1 mole Zn 6.02x10 23 atoms Zn = = 7.48 mol Zn

37 Learning Check 1. Number of atoms in mole of Al a) 500 Al atoms b) 6.02 x Al atoms c) 3.01 x Al atoms 2.Number of moles of S in 1.8 x S atoms a) 1.0 mole S atoms b) 3.0 mole S atoms c) 1.1 x mole S atoms