Chemical Reaction Exam Review

Suppose the mass of two reactants totals 10 grams. After the chemical reaction, what should be the total mass of the products?

• 0 grams

• 5 grams

• 10 grams

• 20 grams

What happens to the the atoms in a chemical reaction?

• They turn into energy

• They are destroyed

• They change into atoms of different elements

• They are rearranged

True or false: A chemical equation is a shorthand representation of reactions between two or more substance

• True

• False

If there are 4 Hydrogen atoms on the reactant side of a balanced equation, how many Hydrogen atoms should be on the products side?

• 2

• 3

• 4

• 5

The law of conservation of matter states that:

• matter is neither created nor destroyed

• the mass of the products is always less than the mass of the reactants

• the mass of the products is always greater than the mass of the reactants

• matter is always converted into an equal amount of energy

All of the following are indicators of a chemical reaction except one. Which one is NOT an indicator that a chemical reaction has taken place?

• the dissolving of one substance in another

• a color change

• the production of gas bubbles

• the production of heat or light

When two substances were combined, bubbles were produced and the temperature dropped. This most likely means that:

• the two substances are non-reactive

• a chemical reaction took place

• one substance dissolved in the other

• the two substances had low boiling points

A balanced chemical equation is one in which:

• the reactants and products have equal volumes

• the same compounds are present in both the reactants and the products

• the reactants and the products have equal densities

• the number of atoms of each element is the same in both the reactants and the products

The idea that matter is neither created nor destroyed in chemical reaction is known as:

• second law of thermodynamics

• law od conservation of chemicals

• law of conservation of energy

• law of conservation of mass

Which observation would most likely indicate that an endothermic reaction has occurred?

• an increase in temperature

• a color change

• a decrease in temperature

• the production of gas bubbles