Unit 6 Test Review

When a chemical reaction produces a solid it is called

• a precipitate.

• a reactant.

• a molecule.

• the mass of the product.

According to the law of conservation of mass, the total mass of the reacting substances is

• always more than the total mass of the products.

• always less than the total mass of the products.

• sometimes more and sometimes less than the total mass of the products.

• always equal to the total mass of the products.

A chemical equation is balanced when

• coefficients of the reactants equal the coefficients of the products.

• each kind of atom has the same amount on both sides of the reaction

• products and reactants are the same chemicals.

• subscripts of the reactants equal the subscripts of the products.

In the word equation, sodium oxide + water → sodium hydroxide, the formula for

sodium hydroxide is represented by

• Na₂OH.

• NaOH.

• NaO₂.

• Na₂O.

How would oxygen be represented in the formula equation for the reaction of methane and oxygen to yield carbon dioxide and water?

• oxygen

• O

• O₂

• O₃

Which of the following is a formula equation for the formation of carbon dioxide from carbon and oxygen?

• Carbon plus oxygen yields carbon dioxide.

• C + O₂ → CO₂

• CO₂ → C + O₂

• 2C + O → CO₂

In an equation, the symbol for a substance in dissolved in water is followed by

• (l)

• (g)

• (aq)

• (s)

In an equation, the symbol for a substance in the gas state is followed by

• (l)

• (g)

• (aq)

• (s)

In an equation, the symbol for a substance in the solid state is followed by

• (l)

• (g)

• (aq)

• (s)

When the equation Fe₃O₄ + Al → Al₂O₃ + Fe is correctly balanced, what is the coefficient of Fe?

• 3

• 4

• 6

• 9