Chemical Reactions and Equations Review

The law of conservation of matter states that:

• matter is neither created nor destroyed.

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

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

• matter is always converted into an equal amount of energy.

Tags

NGSS.MS-PS1-5

Which one is NOT an indicator that a chemical reaction has taken place?

• the production of heat or light

• a color change

• the production of gas bubbles

• the dissolving of one substance in another

Tags

NGSS.MS-PS1-2

Before a chemical reaction, the total mass of two reactants is measured to be 40 grams. After the reaction, what should be the total mass of the products?

• 0 grams

• 20 grams

• 40 grams

• 80 grams

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

When two clear liquids were combined in a beaker, the temperature increased and a yellow powder formed. This most likely means that:

• a chemical reaction took place.

• one substance dissolved in the other.

• the two substances are non-reactive.

• the two substances had high melting points.

Tags

NGSS.MS-PS1-2

What happens to the atoms in a chemical reaction?

• They turn into energy.

• They are destroyed.

• They change into atoms of different elements.

• They are rearranged.

Tags

NGSS.MS-PS1-5

When baking soda and vinegar are mixed how do we know a chemical reaction occurred?

• The mixture gets cold

• The molecules get rearranged

• carbon dioxide bubbles form

• All other answers are correct

Tags

NGSS.MS-PS1-2

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

• a chemical reaction took place.

• the two substances had low boiling points.

• one substance dissolved in the other.

• the two substances are non-reactive.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

NGSS.MS-PS1-4

Hydrogen and oxygen react to produce water. Which of the following is the correctly balanced chemical equation for this reaction?

• H2 + O2 → H2O

• 2H2 + O2 → 2H2O

• H2 + O2 → H4O2

• 2H2 + 2O2 → 4H2O

Tags

NGSS.MS-PS1-5

What happens when a catalyst is added to chemically reactive substances?

• A. It may start the chemical reaction

• B. It may speed up the reaction without changing the chemical

• C. Nothing happens

• Both A and B may occur

Tags

NGSS.HS-PS1-5

Which is NOT a product of an exothermic chemical reaction?

• light

• heat

• sound

• Cold

Tags

NGSS.MS-PS1-4