Chemical Reactions

What is a chemical reaction?

• a process of bonding substances together

• a process that leads to filled valence shells

• a process that releases or consumes energy

• all of the choices

What is a chemical equation?

• a diatomic molecule

• a shorthand representation of a chemical bond

• a shorthand representation of a chemical reaction

• a substance

What are substances on the left side of a chemical equation called?

• electrons

• groups

• products

• reactants

What are substances on the right side of a chemical equation called?

• electrons

• groups

• products

• reactants

What does the number in front of the molecular symbol mean?

• It shows that there is only one molecule present in a reaction

• It shows the number of molecules in the reaction

• It shows the number of reactions that took place

• All of the choices

Can the subscripts in a chemical reaction be changed?

• Cannot be determined

• Maybe, depending on the energy released

• No, they define the molecules in the reaction

• Yes, to balance the equation

Chemical reactions proceed under the law of definite proportions:

• always

• cannot be determined

• never

• sometimes

16.05 g of methane reacts completely with 64.00 g of oxygen to form carbon dioxide and water. What will be the total weight of the CO₂ and H₂O?

• 80.05

• 64

• 16.05

• the weight cannot be determined

What is a limiting reactant?

• a reagent that is found in excess in a chemical reaction

• a reagent that will be consumed completely during a reaction

• a reagent that is not present

• all of the choices

When this equation (C₃H₈ + O₂ -> CO₂ + H₂O ) is balanced, the coefficient in front of carbon dioxide is:

• 1

• 12

• 3

• 6