Chemistry I
Chapter 9
- Just as compounds have definite ratios of elements, chemical reactions have definite ratios of reactants and products.
- Stoichiometry--calculating of the quantities of any substance involved in a chemical reaction from the quantities of the other substances.
- the balanced equation gives the ratios of the formula units of all the reactants and products, giving it the ratio of moles of reactants and products
2 Na + Cl2 ---> 2 NaCl
2 moles + 1 mole ---> 2 moles
Steps for solving problems:
- Step 1: Write a balanced equation
- Step 2: Convert grams to moles
- Step 3: Do a mole to mole conversion
- Step 4: Change moles to grams
Practice Problems
1. Calculate the number of moles of sulfuric acid that must react completely with sodium hydroxide to produce 1.55 mol of sodium sulfate. (Answer: 1.55 mol)
2. A sample of 0.14 moles of solid potassium chlorate is heated. How many grams of oxygen are produced? (Answer: 3.36 g)
3. Calculate the mass of sodium metal that will react with 105.0 grams of chlorine to form sodium chloride. (Answer: 136.25 g)
4. Determine the mass of carbon dioxide after the complete combustion of C3H9 and forms 3.5 grams of water. (Answer: 5.7 g)
More Practice Problems
A) How many moles of sodium nitrate will be formed from the reaction of 3.4 grams of barium nitrate and 2.5 grams of sodium sulfate? (Answer: 0.026 mol)
B) When 0.2 moles of aluminum chloride reacts with 0.7 moles silver nitrate, how many grams of silver chloride will be formed? (Answer: 85.99 g)
C) When 10.1 grams of ethyl alcohol, C2H5OH, undergoes a complete combustion with 36.1 grams oxygen gas, how many moles of carbon dioxide will be formed? How many grams of water will be formed? (Answer: 0.44 mol; 11.85 g)