Chapter 12 Review – Stoichiometry

  1. State the law of conservation of mass (matter) –
  1. What part of a balanced chemical equation represents the number of moles of each compound/element?
  1. Why is the mole and mole ratios so important in stoichiometry?
  1. Using the law of conservation of mass, fill in the missing masses for each chemical equation:
  1. 2 H2 + O2  2H2O

16.2 g 2.0 g _____ g

  1. CaO + CO2  CaCO3

112 g _____ g 200. g

  1. 2 Fe + 3 Cl2  2 FeCl3

_____ g 10.0 g 15.25 g

  1. How does the law of conservation of mass allow for stoichiometric calculations to be valid? (think about question 4).

How can we use the law of conservation of mass to calculate the amount of excess reactant used in a synthesis chemical reaction?

  1. Solve the following. Use dimensional analysis and the conversion box. Use correct sig figs and units in your answer. Balance each equation before you begin!
  1. How many moles of zinc must be reacted with hydrochloric acid to form 3.7 moles of hydrogen gas?

Zn + HCl ZnCl2+H2

  1. Howmanygramsof iron (II) chloride canbemadebycombining6.42 g ofiron(II)sulfidewithanexcess ofhydrochloricacid?

FeS +HCl  FeCl2 +H2S

  1. Calculatethenumberofgramsofpotassiumnitratenecessarytoproduce1.40 molesofoxygen gas.

KNO3  KNO2 + O2

  1. Howmanymolesofchlorinegasmustbereactedwithexcesssodiumiodideif12.02 g ofsodium chloride are needed?

NaI +Cl2  NaCl + I2

  1. If you are given 17.0 g of nitrogen gas and 11.0 g of oxygen gas, determine the theoretical yield of nitrogen dioxide gas produced in grams?

N2 + O2  NO2

  1. (You must first determine the Limiting Reactant) SHOW ALL WORK HERE!!!

The limiting reactant is ______

  1. How much of the excess reactant is used up in the reaction? (Hint: Law of conservation of mass)
  1. How much excess reactant remains at the end of the reaction (is not used up)?

8. If 14.6 g of product is actually produced experimentally from the reaction described in the previous question, what is the % yield of product?