Chem Review
NOT FOR ELECTRONIC STUDENT ACCESS
ONLY FOR CLASSROOM USE!!
Unit 9: Stoichiometry
Practice
1. Differentiate between the significance of the coefficients in a balanced chemical equation and the significance of the subscripts in a chemical formula.
· Coefficients show the correct proportions of atoms and molecules in a chemical reaction. They are normal sized numbers placed at the beginning of the chemical formulas in a chemical reaction during the process of balancing. They tell how many of an entire chemical formula is in a reaction.
· Subscripts show the correct proportions of atoms/ions in a chemical formula. They are the small numbers within the chemical formula. They tell how many individual atoms/ions are present.
2. State the Law of Conservation of Mass and explain its relationship to stoichiometry. The Law of Conservation of Mass states that “Matter can neither be created nor destroyed during a chemical reaction.” This law is dictates the necessity for balancing a chemical equation with coefficients; if we didn’t balance equations, we would be created and/or destroying chemicals.
3. mole-mole problem: One disadvantage of burning propane (C3H8) is that carbon dioxide is one of the products. The released CO2 increases the growing concentration of CO2 in the atmosphere. How many moles of carbon dioxide are produced when 10.0 moles of propane are burned in excess oxygen on a gas grill? C3H8 + 5O2 → 3CO2 + 4H2O
4. mole-mass problem: Water decomposes to produce hydrogen gas and oxygen gas. How many grams of water would be required to produce 10.0 moles of hydrogen gas?
2H2O → 2H2 + O2 MMH2O = 18.015 g/mol
5. mass-mole problem: If 25.0 grams of carbon dioxide are used in photosynthesis how many moles of glucose (C6H12O6) could be Produced according to the following equation: 6CO2 + 6H2O C6H12O6 + 6O2
MMCO2 = 44.009 g/mol
6. mass-mass problem: One series of reactions that inflates air bags in automobiles
ONLY FOR CLASSROOM USE!!
Unit 9: Stoichiometry
Practice
1. Differentiate between the significance of the coefficients in a balanced chemical equation and the significance of the subscripts in a chemical formula.
· Coefficients show the correct proportions of atoms and molecules in a chemical reaction. They are normal sized numbers placed at the beginning of the chemical formulas in a chemical reaction during the process of balancing. They tell how many of an entire chemical formula is in a reaction.
· Subscripts show the correct proportions of atoms/ions in a chemical formula. They are the small numbers within the chemical formula. They tell how many individual atoms/ions are present.
2. State the Law of Conservation of Mass and explain its relationship to stoichiometry. The Law of Conservation of Mass states that “Matter can neither be created nor destroyed during a chemical reaction.” This law is dictates the necessity for balancing a chemical equation with coefficients; if we didn’t balance equations, we would be created and/or destroying chemicals.
3. mole-mole problem: One disadvantage of burning propane (C3H8) is that carbon dioxide is one of the products. The released CO2 increases the growing concentration of CO2 in the atmosphere. How many moles of carbon dioxide are produced when 10.0 moles of propane are burned in excess oxygen on a gas grill? C3H8 + 5O2 → 3CO2 + 4H2O
4. mole-mass problem: Water decomposes to produce hydrogen gas and oxygen gas. How many grams of water would be required to produce 10.0 moles of hydrogen gas?
2H2O → 2H2 + O2 MMH2O = 18.015 g/mol
5. mass-mole problem: If 25.0 grams of carbon dioxide are used in photosynthesis how many moles of glucose (C6H12O6) could be Produced according to the following equation: 6CO2 + 6H2O C6H12O6 + 6O2
MMCO2 = 44.009 g/mol
6. mass-mass problem: One series of reactions that inflates air bags in automobiles