Chemistry 11

Mole Unit VI

Lesson Date Topic WS

1. The Molar Mass 1

2. Mole Conversions 2

3. Calculating Atoms 3

4. Empirical Formula 4

5. Percentage Composition Empirical Formula 5

6. Mole Calculations to Molecular Formula 6

7. Identify that Gas 7

8. Practice Test 1 8

9. Practice Test 2 9

Worksheet # 1 Mole conversions

Describe each particle as an atom, molecule or a formula unit.

1. CO₂

2. KCl

3. C

4. AgNO₃

5. NH₄CH₃COO

6. O₂

7. Os

8. SO₃

9. RbCl

10. CaCO₃

11. Ag

12. NH₃

13. Cl₂

14. Se

15 The electrolysis of water using H₂SO₄ as a catalyst is used to generate hydrogen gas. For every 1 electron consumed 1 atom of hydrogen (exact) is generated. An amp meter is used to measure the rate of electron consumption.

1.00 coulomb = 6.24 x 10 ¹⁸ electrons.

If 1.00 g of hydrogen is generated at a current of 1.50 amps (1 amp = 1 coulomb per second) and over time period of 17.865 hours, calculate Avogadro’s number (the number of atoms in 1.00g of hydrogen). Use unit analysis! Start the unit analysis with 17.865 h and end with atoms H.

16. State Avogadro's # three different ways describing the number of atoms in a mole, formula units in a mole, and molecules in a mole.

Use Unit Analysis to Change from particles to moles or from moles to particles. Note that a particle is an atom, molecule, or formula unit.

17. Covert 5.44 x 10²⁶ at Co to moles.

18. Convert 2.4 moles CO₂ to molecules.

19. Covert 4.56 x 10²⁴ molecules CO₂ to moles.

20. Convert 10.9 moles CuSO₄ to FUs.

21. Convert 5.33 x 10²⁵ FU to moles NaCl.

22. Convert 2.4 moles C to atoms.

23. Covert 9.11 x 10²⁵ molecules SO₃ to moles.

24. Convert 2.9 moles CaSO₄ to FUs.

24. Convert 5.55 x 10²⁴ FU to moles KF.

Draw Electron-dot Diagrams for each of the following. Remember, use brackets for cations or anions. Covalent compounds do not require brackets.

25. CCl₄ 26. NaCl

27. CO₂ 28. Li₂SO₄

29. HCN 30. NO₃^-

Worksheet # 2 The Mole

Calculate the molar mass of the following compounds. Remember to determine the mass of each element and add the mass of the elements together.

1. KI 2. Mg₃(PO₄)₂

3. NiO 4. H₂O

5. BaF₂ 6. Ti(SO₄)₂^.6H₂O

7. CuS 8. ZnHCO₃

9. Li₃N 10. PdSO₄

11. NaI 12. K₃PO₄

13. FeO^.6H₂O 14. NaOH

15. AlF₃^.8H₂O 16. Ga₂(CO₃)₃

17. CuH₂ 18. Zn(CH₃COO)₂

19. NiN 20. BaSO₄^.5H₂O

Define the following. The first one is done for you.

21. Atomic mass is the mass of 1 mole of atoms.

22. Molecular mass is

23. Formula mass is

24. Molar mass is

25. Describe as a formula unit, molecule, or atoms.

Au KCl NH₄Cl H₂O CO₂ K P₂O₅

Cu K₂SO₄ C NH₃ C₁₂H₂₄O₁₁ NaCl Br

Convert from grams to moles. Show all work using unit analysis.

26. 100. g H₂O

27. 250. g MgCl₂

28. 0.266 g C₆H₁₂

29. 1.2 x 10^-4 g Fe

Convert each quantity to moles.

30. 500. g H₂O

31. 0.269 g P₂O₅

32. 135.3 g CaSO₄

33. 214.7 g CH₄

34. 25.3 g C₆H₁₂O₆

Convert from atoms, molecules, or formula units to grams.

35. 6.55 x 10²⁴ atoms Ag

36. 8.66 x 10²⁶ FU RbCl

37. 5.00 x 10 ³² molecules N₂H₄

38. 5.3 x 10²⁹ FU KBr

39. 25.3 x 10²⁸ molecules C₄H₁₀

40. 1.33 x 10²⁵ atoms Ag

41. 1.55 x 10¹⁶ FU NaCl

42. 2.55 x 10 ²⁷ molecules NH₃

43. 5.3 x 10²⁹ FU KBr

Convert from grams to atoms, molecules, or formula units.

44. 100. g H₂O₂

45. 2.6 g MgF₂

46. 0.211 g C₅H₁₂

47. 3.33 x 10^-2 g Fe

48. 0.126 g Co

Worksheet #3 Calculating Atoms and Molecules

1. Measure the mass some Calcium. Calculate the number of atoms. Add 50 mL water to a 250 mL fleaker. Add the calcium to the beaker and cover with a plastic funnel. Light the funnel after about 8 seconds. What gas is produced by the reaction?

2. Measure the mass of a Copper cylinder. Calculate the number of atoms in the cylinder.

3. Measure the mass of an Iron cylinder. Calculate the number of atoms in the cylinder.

4. Measure the mass of a Magnesium cylinder. Calculate the number of atoms in the cylinder.

5. Measure the mass of an Aluminum cylinder. Calculate the number of atoms in the cylinder.

6. Measure the mass of a small amount of dry ice (be quick- it won’t last long due to sublimation). Calculate the number of molecules of CO₂.

7. Calculate the mass of 4.56 x 10²⁵ atoms of Sr.

8. Calculate the mass of 6.33 x 10²⁰ molecules of CO₂.

9. Calculate the mass of 8.66 x 10²⁶ FU of SrO.

10. Calculate the mass of 2.3 x 10²⁸ FU of SrCO₃^.H₂O.

11. Calculate the number of H atoms in 5.02 g of CH₄. There are 4 atoms of H in one molecule of CH₄.

12. Calculate the number of O atoms in 200. g Al₂(SO₄)₃. There are 12 atoms of O in one formula unit of Al₂(SO₄)₃.

13. Calculate the mass of CaCO₃ that contains 2.00 x 10²⁸ atoms of O. There are 3 atoms of O per one FU of CaCO₃.

14. Calculate the mass of Al₂(SO₄)₃ that contains 2.00 x 10²⁸ atoms of O.

15. Calculate the mass of Al₂(SO₄)₃ that contains 2.00 x 10²⁰ atoms of Al.

16. Calculate the number of Al atoms in 500. g Al₂(SO₄)₃.

Draw Electron-dot Diagrams for each of the following. Remember, use brackets for cations or anions. Covalent compounds do not require brackets.

17. C₂F₆ 18. KClO₄

19. NH₃ 20. Li₂CO₃

21. N₂ 22. PO₃^3-

Worksheet #4 Empirical Formula

Use a calculation to determine the empirical formula of each of the following compounds. Show all of your work.

1. A compound is found to be 6.353 g Ag, 0.823 g N, and 2.824 g of O. Calculate the empirical formula of the compound.

2. A compound is found to be 6.25 g Pb, 0.846 g N, and 2.90 g of O. Calculate the empirical formula of the above compound.

3. A compound is found to be 1.00 g Ca, 0.700 g N, and 2.40 g O. Calculate the empirical formula of the above compound.

4. A compound is found to be 27.91 % Fe, 24.08 % S, and 48.0 % O. Calculate the empirical formula.

5. A compound is found to be 15.38 % Co, 40.74 % Cr, and 43.88 % O. Calculate the empirical formula.

6. A compound is found to be 63.65 % C, 10.71 % H, 18.56 % N, and 7.072 % O. Calculate the empirical formula.

7. Change 5.0 x 10²⁶ formula units CoCl₂^. 6H₂O to grams.

8. Convert 2.36 g FeSO₄·5H₂O to formula units.

9. Change 3.65 x 10²² molecules CO₂ to grams.

10. Convert 2.36 g grams P₂O₅ to molecules.

Worksheet # 5 Percentage Composition, Molecular and Empirical Formula

Complete the following chart.

Empirical Formula Molar Mass Molecular Formula Molecular

Mass

1. CH 78 g/mole

2. C₃H₂O 162.06 g/mole

3. C₁₂H₂₁N₃O₃

4. C₄H₈O 216 g/mole

5. C₂H₄NO 174 g/mole

6. C₁₅H₃₃N₃O₃

7. C₂H₂O 210 g/mole

8. C₃H₇NO 292 g/mole

9. C₄H₈N₂O₂

10. CCl₃ 237 g/mole

11. If the empirical formula for a compound is C₂H₃O and its molecular mass is 129 g/mole, what is the molecular formula.

12. A compound is 49.2% P and 50.8% O, calculate the empirical formula. If the molecular mass is 126 g/mole, calculate the molecular formula.

13. A compound is 62.54 % Pb, 8.46 % N, and 29.0 % O, calculate the empirical formula.

14. A compound is 46.08 % C, 27.0 % N, and 27.0 % O. Calculate the empirical formula. If the molecular mass is 832 g/mole, calculate the molecular formula.

15. Oil of citronella is a mosquito repellent is 87.8% C and 12.2% H. Calculate the empirical formula. If the molecular mass is 205 g/mole, calculate the molecular formula.

Calculate the percentage composition for:

16. ZnSO₄

17. Al₂(CO₃)₃

18. Ca₃(PO₄)₂

19. Convert 3.66 kg CO₂ to molecules.

20. Covert 4.0 x 10²⁶ FU of MgCl₂ to Kg.

21. In a propane tank there are 9.0 Kg of C₃H₈, calculate the number of H atoms. (First calculate molecules and then H atoms).

22. A certain mass of complex Co(NH₃)₆Cl₃ was found to contain 2.65 x 10²¹ atoms of H, calculate the mass of cobalt III chloride hexammine. (Change the number of atoms to FU’s first).

Worksheet # 6 Mole Calculations to Molecular Formula

1. Convert 500. g NaCl to formula units.

2. Convert 9.8x10²⁴ molecules of C₂H₆ to grams.

3. Calculate the number of O atoms in 50.0 lb of dry ice CO₂.

(2.21 lb = 1.00Kg)

4. Calculate the percentage composition of Al₂(SO₄)₃. 3 significant figures!

5. Calculate the molar mass of Co₂(SO₄)₃ ^. 6H₂O

6. The empirical formula for a compound is C₂H₅O and its molecular mass is 135 g/mol. The molecular formula is:

7. A compound is 24.4 % Ca, 17.1 % N and 58.5 % 0. Calculate the empirical formula.

8. Hydroquinone, a chemical used for photographic developing, is 65.45 % C,

5.51 % H and 29.09 % O. Calculate the empirical and molecular formula. The molecular mass is 110g/mol.

9. A compound is 50.5 % C, 5.26 % H, and 44.2 % N, calculate the empirical formula. If the molecular mass is 380.2 g / mole, calculate the molecular formula.

10. A compound is 50.5 % C, 5.26 % H, and 44.2 % N, calculate the empirical formula. If the molecular mass is 285.15 g/mole, what is the molecular formula?

Challenge Problems

11. When 15.0 g of a compound known to contain C, H, O, and S was burned, 16.2 g of CO₂, 6.63 g of H₂O, and 15.7 g of SO₂ were produced. What is the empirical formula of the compound?

12. When 51.3 g of a compound known to contain C, H, N, and O was burned, 84.2 g of CO₂, 20.7 g of H₂O, and 10.7 g of N₂ were produced. What is the empirical formula of the compound?

Worksheet #7 Identify that Gas

1. A volume of a gas weighs 0.256 g. An equal volume of H₂ weighs 0.01163 g. Calculate the molecular mass of the gas. Assuming that this gas is a common gas, what do you think the gas could be? Show some work!

2. A volume of a gas weighs 2.12 g. An equal volume of He weighs 0.265 g. Calculate the molecular mass of the gas. Assuming that this gas is a common gas, what do you think the gas could be? Show some work!

3. A volume of a gas weighs 0.235 g. An equal volume of He weighs 0.02043 g. Calculate the molecular mass of the gas. This gas is a gas produced by automobile pollution, what do you think the gas could be? Show some work!

4. A volume of a gas weighs 0.37216 g. An equal volume of H₂ weighs 0.01163 g. Calculate the molecular mass of the gas. Assuming that this gas is a on that is produced by burning matches, what do you think the gas could be? Show some work!

5. A volume of a gas weighs 0.02051g. An equal volume of CO₂ weighs .02654 g. Calculate the molecular mass of the gas. Assuming that this gas is a smelly one that is produced by rotten eggs, what do you think the gas could be? Show some work! This gas is also added to natural gas to make it smell so that leaks can be detected.

6. Convert 1.65 g CO₂ to molecules.

7. Convert 12.5 Kg of SO₂ to molecules.

8. Covert 2.0 x 10²⁶ FU of MgCl₂ to g.

9. In a propane tank there are 8.0 Kg of C₃H₈. Calculate the number of H atoms. (First calculate molecules and then H atoms).

10. A certain mass of complex Co(NH₃)₆Cl₃ was found to contain 2.65 x 10²⁵ FU, calculate the mass of cobalt III chloride hexammine.

11. The empirical formula of a compound is C₃H₁₁O₃ and its molecular mass is 380.44 g/mole. Determine the molecular formula.

12. Calculate the percentage composition of Co(NH₃)₆Cl₃ to three significant figures.

13. A compound is 27.73 % Mg, 23.58 % P, and 48.69 % O, calculate the empirical formula.

14. 9, 10-diehydro-6-methylergoline-8-carboxylic acid (LSD) a drug with psychomimetric properties is 71.6 % C, 6.03 % H, 10.4 % N, and 11.9 % O. If the molecular mass of the compound is 268.16 g/mol, calculate the empirical and the molecular formula.

15. A volume of a gas containing sulphur and oxygen that is produced by burning coal has a mass of 2.088 g. An equal volume of H₂ has a mass of 0.0658 g. Calculate the molar mass of the gas and determine its formula.

16. Here is the tough one. You can do it- just take it one step at a time!

A compound was known to contain C, H, N, O, and S. When a 5.43g sample was burned the products were 8.43 g CO₂, 1.15 g H₂O, 0.450 g N₂, and 3.07 g of SO₂. Determine the empirical formula of the compound. I left you a whole page- I hope that’s enough. Good luck!

Worksheet #8 Review of Mole Calculations

1. Convert 2.59 g of SO₃ to molecules.

2. Convert 3.56 x 10²⁵ FU of CoCl₄ to Kg.

3. In a propane tank there are 26.5 Kg. of C₂H₆. Calculate the number of H atoms.

4. Describe each atom as an atom, molecule, anion, cation, or a formula unit:

CO₂

Co

AgNO₃

KCl

Cr₂O₇^2-

NH₄⁺

5. Convert 568 g of H₃PO₄ to moles.

6. Convert 3.25 x 10⁵g Rh into atoms.

7. Calculate the molar mass of the following compounds:

Hg₃(PO₄)₂ CuI₂

Pb₂SO₄ Li₂SO₃

8. What is the percent composition of C₂H₆

9. What is the percent composition of CaCl₂^. 2H₂O

10. The empirical formula of a compound is SiH₃. If 0.0275 mol of the compound has a mass of 1.71 g, what is the compounds molecular formula?

11. A compound is 27.73% Mg, 23.58% P, and 48.69% O, calculate the empirical formula.

12. Find the empirical formula for a compound containing 46.3 % Li and 53.7 % O.

13. Convert 5.65 x 10¹⁷ atoms of Fe into grams.

14. A compound contains C, H and O. A 5.90 g sample is burned to yield 11.18 g of CO₂ and 3.66 g H₂O. What is the empirical formula of the compound?

15. A volume of a gas weighs 2.12 g. An equal volume of He weighs 0.265 g. Calculate the molecular mass of the gas. Assuming that this gas is a common diatomic gas, what do you think the gas could be? Show your work.

Worksheet #9 Moles Practice Test 1

1. Convert 5.65 g of SO₂ to molecules.

2. Convert 3.56 x 10²⁵ FU of CuCl₂ to Kg.

3. In a lighter there are 0.52 g. of C₄H₁₀. Calculate the number of H atoms.

4. Describe each atom as an atom, molecule, or a formula unit:

CO₂ ____________

Zn _____________

Ca(NO₃) ₂ _____________

NaCl _____________

CH₃COOH _____________

5. Convert 572 g of HNO₂ to moles.

6. Convert 3.25 x 10⁵ g Ru into atoms.

7. Calculate the molar mass of the following compounds:

Au₃(PO₄)₃ CuBr₂

Pb₃ (PO₄) ₂ Li₂CO₃

8. What is the percent composition of C₃H₁₀

9. What is the percent composition of SrCl₂ ^.3H₂O

10. The empirical formula of a compound is C₃H₈. If 2.00 mol of the compound has a mass of 264.48 g, what is the compounds molecular formula? Hint: first calculate the molar mass by dividing grams by moles.

11. Find the empirical formula for a compound containing 24.45 % Ca, 17.07 % N and 58.53 % O.

12. Find the empirical formula for a compound containing 74.40 % Ga and

25.60 % O.

13. Convert 5.55 x 10¹⁷ atoms of Co into grams.

14. A volume of a gas weighs 3.0475 g. An equal volume of He weighs 0.265 g. Calculate the molecular mass of the gas. Assuming that this gas causes acid rain, what do you think the gas could be? Show your work.

15. Methamphetamine, MDMA, or commonly called ecstasy is an illegal drug from a family called “entactogens”; which literally means in Greek, “touching within”. This drug is considered to be a mood elevator that is:

59.506 % C, 8.0135 % H, 6.9424 % N, 7.934 % O, and 17.604 % Cl. Calculate the empirical formula for MDMA.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
16.  Brodifacoum, a Coumarin derivative used to poison rats, is also used a blood  thinner in small doses. An antidote for this poison is vitamin K, a blood-clotting  agent. This compound contains C, H, Br and O. A 10.00 g sample is burned to  yield 25.633 g of CO2, 3.894 g H2O, and 1.502 g of Br2. What is the empirical  formula of the  compound? The structural formula is shown below.