Name:_____________________________ Date:_____________Moles and Stoichiometry 2016 Mrs. Mannion

A) NO B) NO2 C) N2O D) N2O3

1. What is the empirical formula of a compound with themolecular formula N2O4?

A) 1 mole B) 2 molesC) 3 moles D) 4 moles

2. What is the total number of atoms contained in 1 moleof NH3?

A) CHO B) CH2OC) C6H12O6 D) C12H24O12

3. The molecular formula of glucose is C6H12O6. Whatis the empirical formula of glucose?

A) 22 B) 11 C) 8 D) 4

4. What is the total number of moles of atomsrepresented by the formula Al(C2H3O2)3?

A) ZnCO3 B) Zn(CO3)2

C) Zn2CO3 D) Zn2CO2

5. What is the chemical formula for zinc carbonate?

A) CH2O B) C2H4O2

C) C3H8O D) C4H8O4

6. A compound has the empirical formula CH2O and agram-formula mass of 60. grams per mole. What isthe molecular formula of this compound?

A) 66.0 g B) 94.0 gC) 114 g D) 132 g

7. What is the gram formula mass of (NH4)2SO4?

A) 1.0 g B) 2.0 g C) 3.0 g D) 4.0 g

8. What is the total mass of 2.0 moles of H2(g)?

A) mole B) mole

C) moles D) moles

9. The number of moles of molecules in a -gramsample of is

A) 1.0 mole B) 2.0 molesC) 0.50 mole D) 1.5 moles

10. Which quantity is equivalent to 39 grams of LiF?

A) SO B) SO2 C) SO3 D) S2O3

11. A compound contains 57% sulfur and 43% oxygenby mass. What is the empirical formula of thiscompound?

A) 18% B) 23% C) 32% D) 35%

12. The percent by mass of nitrogen in NH4NO3 (formula mass = 80) is approximately

A) B)

C) D)

13. The percent by mass of oxygen in is equalto

A) B) C) D)

14. Which compound has the highest percentcomposition by mass of strontium?

A) 10.% B) 12% C) 21% D) 79%

15. What is the percent by mass of water present in 1.0mole of CaSO4 • 2H2O?

A) 17.5% B) 35.0%C) 52.5% D) 60.0%

16. What is the percent composition by mass of nitrogenin NH4NO3 (gram-formula mass = 80.0grams/mole)?

A) decompositionB) double replacementC) single replacementD) synthesis

17. Given the balanced equation representing areaction:

Which type of reaction is represented by thisequation?

A) absorbed B) conservedC) formed D) released

18. During all chemical reactions, mass, energy, andcharge are

A) the mass ratios of the substances in the reactionB) the mole ratios of the substances in the reactionC) the total number of electrons in the reactionD) the total number of elements in the reaction

19. The coefficients in a balanced chemical equationrepresent

A) 9 B) 8 C) 5 D) 4

20. When the equation

is correctly balanced using the smallest whole number coefficients, the sum of the coefficients is

A) 5.0 mol B) 10. molC) 20. mol D) 40. mol

21. Given the balanced equation:

CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2O( ) + CO2(g)

What is the total number of moles of CO2 formedwhen 20. moles of HCl is completely consumed?

A) 6.0 g B) 12 g C) 3.0 g D) 24 g

22. Given the reaction:

Mg + 2 HCl ® MgCl2 + H2

What is the total number of grams of Mg consumedwhen 0.50 mole of H2 is produced?

A) 56 g B) 88 gC) 112 g D) 288 g

23. Given the balanced equation representing a reaction:

CaO(s) + CO2(g) CaCO3(s) + heatWhat is the total mass of CaO(s) that reactscompletely with 88 grams of CO2(g) to produce 200.grams of CaCO3(s)?

A) 1.01 × 1024 B) 2.02 × 1024

C) 3.01 × 1023 D) 6.02 × 1023

24. What is the total number of neon atoms contained in20.2 grams of neon gas?

25. Base your answer to the following question on the information below.

A scientist in a chemistry laboratory determined the molecular formulas for two compoundscontaining nitrogen and oxygen to be NO2 and N2O5

Write an IUPAC name for the compound N2O5.

26. Determine the percent composition by mass of oxygen in the compound C6H12O6

27. Show a numerical setup for calculating the percent composition by mass of silicon in .

28. Base your answer to the following question on the information below.

The decomposition of sodium azide, NaN3(s), is used to inflate airbags. On impact, the NaN3(s) isignited by an electrical spark, producing N2(g) and Na(s). The N2(g) inflates the airbag.What is the total number of moles present in a 52.0-gram sample of NaN3(s) (gram- formula mass =65.0 gram/mole)?

29. Base your answer to the following question on the information below.

John Dalton, an early scientist, sketched the structure of compounds using his own symbols forthe elements known at the time. Dalton's symbols for four elements and his drawing of potassiumaluminum sulfate are represented by the diagram below.

Today, it is known that the chemical formula for potassium aluminum sulfate is . It is a hydrated compound because water molecules are included within its

crystal structure. There are 12 moles of H2O for every 1 mole of . The compoundcontains two different positive ions. The gram-formula mass of is 474 gramsper mole.

Show a numerical setup for calculating the percent composition by mass of water in .

30. Base your answer to the following question on the information below.

In an experiment, 2.54 grams of copper completely reacts with sulfur, producing 3.18 grams ofcopper(I) sulfide.Determine the total mass of sulfur consumed.

31. Base your answer to the following question on the information below.

In a titration, milliliters of a solution exactly neutralized milliliters of a solution.

Show a correct numerical setup for calculating the molarity of the solution.

32. In a laboratory experiment, a student determined the mass of the product, KClO3(s), to be 45.7 grams.

a. Calculate the gram formula mass of KClO3(s). Round atomic masses from the Periodic Table tothe nearest tenth. [Show all work. Indicate the correct answer in proper significant figures andinclude an appropriate unit.]

b. Calculate the number of moles of KClO3(s) produced. [Show all work. Indicate the correctanswer in proper significant figures.]

33. Determine the molecular formula for a compound that has the empirical formula and a molarmass of 120. grams per mole.

34. Base your answers to the following questions on the information below.

For health reasons, the element chlorine is added to the drinking water because it will killdisease-causing organisms. Typically 0.50 ppm of chlorine is added to drinking water to make it safe.

In 2.0 liters of drinking water (2000.g), how many grams of chlorine is present? [Show all work.Include in your answer proper units and significant figures.]

35. The decomposition of sodium azide, NaN3(s), is used to inflate airbags. On impact, the NaN3(s) isignited by an electrical spark, producing N2(g) and Na(s). The N2(g) inflates the airbag.

An inflated airbag has a volume of 5.00 x 104 cm3 at STP. The density of N2(g) at STP is 0.00125g/cm3. What is the total number of grams of N2(g) in the airbag?

36. Base your answer to the following question on the information below and on your knowledge of chemistry.

Many breads are made by adding yeast to dough, causing the dough to rise. Yeast is a type ofmicroorganism that produces the catalyst zymase, which converts glucose, , to ethanoland carbon dioxide gas. The balanced equation for this reaction is shown below.

Determine the total mass of ethanol produced when 270. grams of glucose reacts completely to formethanol and 132 grams of carbon dioxide.

37. Base your answer to the following question on the passage below.

Acid rain is a problem in industrialized countries around the world. Oxides of sulfur andnitrogen are formed when various fuels are burned. These oxides dissolve in atmospheric waterdroplets that fall to earth as acid rain or acid snow. While normal rain has a pH between 5.0 and 6.0 due to the presence of dissolved carbondioxide, acid rain often has a pH of 4.0 or lower. This level of acidity can damage trees andplants, leach minerals from the soil, and cause the death of aquatic animals and plants. If the pH of the soil is too low, then quicklime, CaO, can be added to the soil to increase thepH. Quicklime produces calcium hydroxide when it dissolves in water.

Acid rain is a problem in industrialized countries around the world. Oxides of sulfur andnitrogen are formed when various fuels are burned. These oxides dissolve in atmospheric waterdroplets that fall to earth as acid rain or acid snow. While normal rain has a pH between 5.0 and 6.0 due to the presence of dissolved carbondioxide, acid rain often has a pH of 4.0 or lower. This level of acidity can damage trees andplants, leach minerals from the soil, and cause the death of aquatic animals and plants. If the pH of the soil is too low, then quicklime, CaO, can be added to the soil to increase thepH. Quicklime produces calcium hydroxide when it dissolves in water.

Balance the neutralization equation below, using the smallest whole number coefficients.

38. Base your answer to the following question on the information below. The reaction between aluminum and an aqueous solution of copper(II) sulfate is represented bythe unbalanced equation below.

Identify the type of chemical reaction represented by the equation.

Answer KeyMoles and Stoichiometry 2016

1. B2. D3. B4. A5. A6. B7. D8. D9. B10. D11. D12. D13. B14. C15. C16. B17. C18. B19. B20. A21. B22. B23. C24. D25. Responses include,

but are not limitedto, these examples:dinitrogen pentoxide• nitrogen(V) oxide

26. 53.3%27.

28. Significant figuresdo not need to beshown. Acceptableresponses include,but are not limitedto:0.800 mol

29.30. 0.64 g31.32. a) 39.1 + 35.5 +

3(16.0) = 122.6 gb) 45.7g x 1.00mole/122.6g = .373mole

33. . The orderof the elements canvary.

34. 0.0010 g35. 62.5 g36. 138 g or for any

value from 137.8 gto 138.3 g, inclusive

37. 2 HNO3 + 1 Ca(OH)2 1 Ca(NO3)2 + 2H2O

38. — singlereplacement —redox