Chemistry equations

If a chemical reaction such as photosynthesis begins with 6 atoms of carbon (C), how many atoms of carbon (C) should be in the products?

• 12 atoms of carbon (C)

• 6 atoms of carbon (C)

• 3 atoms of carbon (C)

• 2 atoms of carbon (C)

How does a balanced chemical equation satisfy the Law of Conservation of Mass?

• During a chemical reaction, the total amount of matter stays the same.

• During a chemical reaction, matter is destroyed.

• During a chemical reaction, one or more new substances are formed.

• During a chemical reaction, the total number of atoms increases.

Which best explains why the total mass of the product(s) would be less than the total weight of the reactant(s) after a chemical reaction?

• A physical change occurred.

• Atoms involved in the reaction lost mass.

• Precipitates were created in the new solution.

• Gases were released to the atmosphere.

Which shows one example of a physical change and one example of a chemical change?

• boiling water and melting wax

• rusting iron and baking a cake

• dissolving powder and shredding paper

• freezing water and burning coal

Substance A has a mass of 7 grams. When substance A was mixed with substance B, a new substance was formed. Which statement best describes the Law of Conservation of Mass?

• The mass of substance B is equal to the mass of the product.

• The mass of the product is equal to the mass of the reactants.

• The mass of the product is less than the mass of the reactants.

Which is true of a chemical equation?

• Products and reactants must be balanced.

• Subscripts must be used with all products and reactants.

• Energy must be included in the beginning of the reaction.

• Coefficients must be used with all products and reactants.

What is the total number of oxygen atoms on the reactant side of the equation shown below?

CH3COOH + NaHCO3 → CH3COONa + H2O + CO2

• 2

• 3

• 5

• 7

Which best describes a solid produced in a solution during a chemical reaction?

• acid

• solute

• reactant

• precipitate

Which is indicated if a gas forms when two or more substances are mixed?

• physical change

• chemical change

• physical property

• chemical property

Which would provide the best evidence that a chemical reaction had occurred?

• phase change

• gas formation

• change in mass

• change in shape