Endothermic and Exothermic reaction

What happens during all endothermic changes?

• A gas is produced.

• Solids melt.

• The temperature decreases

• There is a colour change.

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.

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.

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.

Which change must take place in an endothermic reaction?

• Bubbles of gas are released.

• The mass decreases.

• The temperature decreases.

• The temperature increase

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

• A

• B

• C

• D

In an exothermic reaction, heat is ...

• absorbed from the environment

• released into the environment

If a chemical reaction is EXOTHERMIC, the temperature would....

• Stay the same
• Increase
• Decrease

____ reactions usually feel cold.

• endothermic

• exothermic

The graph above is from which type of reaction?

• Endothermic reaction

• Exothermic Reaction