Unit 4: Chemical Reactions Review

Which observation does NOT indicate a chemical reaction has taken place?

• formation of a precipitate

• production of a gas

• production of heat and/or light

• change in the total volume of the substances

A solid produced as a result of the reaction between two aqueous solutions is

• a precipitate.

• a reactant.

• a molecule.

• a soluble product.

What does the symbol “g” beside a formula in a chemical equation represent?

• the substance is a gas

• the chemical produces heat

• the chemical is dissolved

• the chemical is a catalyst in water

A catalyst is _________________.

• the product of a combustion reaction

• used to speed up a reaction

• a reactant in a synthesis reaction

• something that serves no purpose in a chemical reaction

To balance a chemical equation, it may be necessary to adjust the

• subscripts on covalent compounds

• subscripts on ionic compounds

• coefficients

A chemical equation is considered balanced when the

• coefficients of the reactants equal the coefficients of the products

• same number of each kind of atom appears in the reactants and in the products

• products and reactants are the same chemicals

• subscripts of the reactants equal the subscripts on the products

What type of change produces a new substance?

• chemical

• physical

What kind of change would melting be?

• physical

• chemical

Which set of coefficients correctly balance the equation: __N₂H₄O₂ --> __ N₂ + __H₂O ?

• 1 --> 2, 2

• 2 --> 2, 2

• 2 --> 1, 1

• 1 --> 1, 2

What kind of change would burning a hydrogen filled balloon with a match be?

• physical

• chemical