Quiz: Chemical Reactions and Equations Review

What is a clear visible indicator that a chemical reaction took place?

• Salt mixing with water

• Oil and vinegar separating

• A clear liquid changing to yellow when combined with another liquid

• Ice becoming water when warm

Tags

NGSS.MS-PS1-2

Endothermic reactions mean energy is "entering" or absorbed, but what about the temperature? (think photosynthesis)

• a decrease in temperature

• formation of a precipitate

• gas bubbles

• a color change

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

What 2 indicators tell us a chemical reaction is taking place? (Choose 2)

• A liquid is blue in color

• vapor or gas is exiting the flask

• the liquid changes to a solid when frozen

• bubbles can be seen forming

Tags

NGSS.MS-PS1-2

Before burning, the initial mass of a candle is 9.5 grams. After burning for several minutes, the final mass is 5.4 grams. Which of the following is the best explanation for the measured masses before and after the chemical reaction?

• We cannot measure the mass of a solid.

• The candle doesn't change at all as it burns.

• The candle burning makes the candle heavier at the end measurement.

• As the candle burns, gas vapor is released and the candle gets smaller, resulting in lower final mass.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Reactants are on ____ side of a chemical equation.

(Think: Reactants React to Produce Products)

• right

• left

• either side

• no side

C₁₂H₂₄ + O₂ -> CO₂ + H₂O

Which are the reactants? (Just look at the sides!)

• C₁₂H₂₄ + O₂

• O₂

• CO₂ + H₂O

• H₂O

Tags

NGSS.MS-PS1-2

How can you tell from a chemical equation that it is an actual chemical reaction and not just a physical change?

CH₄ + 2O₂ -> CO₂ + 2H₂O

• The colors of the coefficients and subscripts

• It's too difficult to tell differences

• The reactants and products are different

• The letters are always capitalized in products and reactants

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

On a gas stove, a flame can be seen when turned on and used to heat up the burner for cooking. Is this methane burning and heating up Exothermic or Endothermic? (Think of the flame, like a firework)

• Exothermic

• Endothermic

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-5

In a chemical reaction...

• atoms can form bonds, break bonds or rearrange

• atoms can form bonds only

• new atoms/matter is created

• some atoms disappear or get "destroyed"

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What indicator would tell me that a chemical reaction took place?

• temperature stability

• Color change

• liquid staying flat

• no changes at all

Tags

NGSS.MS-PS1-2