Practice Problems: Stoichiometry

1. Balance the following chemical reactions:
   
   a. CO + O₂ CO₂
   
   b. KNO₃ KNO₂ + O₂
   
   c. O₃ O₂
   
   d. NH₄NO₃ N₂O + H₂O
   
   e. CH₃NH₂ + O₂ CO₂ + H₂O + N₂ Hint
   
   f. Cr(OH)₃ + HClO₄ Cr(ClO₄)₃ + H₂O
2. Write the balanced chemical equations of each reaction:
   
   a. Calcium carbide (CaC₂) reacts with water to form calcium hydroxide (Ca(OH)₂) and acetylene gas (C₂H₂).
   
   b. When potassium chlorate (KClO₃) is heated, it decomposes to form KCl and oxygen gas (O₂).
   
   c. C₆H₆ combusts in air. Hint
   
   d. C₅H₁₂O combusts in air.
3. Given the following reaction: Na₂S₂O₃ + AgBr NaBr + Na₃[Ag(S₂O₃)₂]
   
   a. How many moles of Na₂S₂O₃ are needed to react completely with 42.7 g of AgBr?
   
   b. What is the mass of NaBr that will be produced from 42.7 g of AgBr?
   
   Hint
4. From the reaction: B₂H₆ + O₂ HBO₂ + H₂O
   
   a. What mass of O₂ will be needed to burn 36.1 g of B₂H₆?
   
   b. How many moles of water are produced from 19.2 g of B₂H₆?
5. Calculate the mass (in kg) of water produced from the combustion of 1.0 gallon (3.8 L) of gasoline (C₈H₁₈). The density of gasoline is 0.79 g/mL.
6. One mole of aspartame (C₁₄H₁₈N₂O₅) reacts with two moles of water to produce one mole of aspartic acid (C₄H₇NO₄), one mole of methanol (CH₃OH) and one mole of phenylalanine.
   
   a. What is the molecular formula of phenylalanine?
   
   b. What mass of phenylalanine is produced from 378 g of aspartame?
7. KO₂ is used in a closed-system breathing apparatus. It removes carbon dioxide and water from exhaled air. The reaction for the removal of water is: KO₂ + H₂O O₂ + KOH. The KOH produced is used to remove carbon dioxide by the following reaction: KOH + CO₂ KHCO₃.
   
   a. What mass of KO₂ produces 235 g of O₂?
   
   b. What mass of CO₂ can be removed by 123 g of KO₂?