Exothermic and Endothermic Reaction

What happens during all endothermic changes?

• A gas is produced.

• Solids melt.

• The temperature decreases

• There is a colour change.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Solid sodium carbonate is added to vinegar in a beaker and stirred.

The water in the watch glass freezes.

Which statement about the reaction explains why the water freezes?

• It is a redox reaction.

• It is an endothermic reaction.

• It is catalysed by sodium carbonate.

• It is thermal decomposition.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Which temperature changes occur during exothermic and endothermic reactions?

• A

• B

• C

• D

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

The diagram shows how the temperature change is measured when magnesium powder reacts with dilute hydrochloric acid. Thermometer reading before adding magnesium powder = 20.6 °C Thermometer reading after adding magnesium powder = 32.4 °C Which statement is correct?

• The reaction is endothermic and gives out heat.

• The reaction is endothermic and takes in heat.

• The reaction is exothermic and gives out heat.

• The reaction is exothermic and takes in heat.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Which statement about chemical reactions is not correct?

• A higher temperature increases the rate of an endothermic reaction.

• Chemical energy is converted into thermal energy in an endothermic reaction.

• Temperature decreases in an endothermic reaction and there is an increase in chemical energy.

• Temperature increases in an exothermic reaction because there is an increase in thermal energy.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS1-5

Methane reacts with oxygen, releasing heat. Which statement explains the energy changes in this reaction?

• Chemical energy is changed into thermal energy.

• Energy is made in the reaction.

• The heat released increases the temperature of the surroundings.

• The reaction is endothermic.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

Which statement describes an exothermic reaction?

• It gives out thermal energy.

• It needs energy to start it.

• It neither gives out nor takes in energy.

• It takes in energy.

Tags

NGSS.HS-PS1-4

Which change must take place in an endothermic reaction?

• Bubbles of gas are released.

• The mass decreases.

• The temperature decreases.

• The temperature increase

Tags

NGSS.HS-PS1-4

The initial and the final temperatures of four different reactions are recorded. Which reaction is the most exothermic?

• A

• B

• C

• D

Tags

NGSS.HS-PS1-4

The energy level diagram for a reaction is shown.

Which statement is correct?

• X is the energy change of the reaction.

• Y is the activation energy of the reaction.

• The energy change of the reaction is larger than the activation energy of the reaction.

• The reaction is exothermic.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1