Chemical energetics: Exothermic and endothermic reactions

Which of the following must be included when drawing and labeling reaction pathway diagrams for exothermic and endothermic reactions?

• Only reactants and products

• Reactants, products, enthalpy change (ΔH), and activation energy (Ea)

• Only enthalpy change (ΔH) and activation energy (Ea)

• Only activation energy (Ea)

Chemical reactions involve ______ changes. Fill in the blank.

• energy

• physical

• mechanical

• magnetic

The amount of energy contained in the bonds of the chemicals is called the ________. (slight simplification)

• enthalpy

• entropy

• activation energy

• kinetic energy

In equations, Enthalpy is given the letter:

• E

• H

• C

• T

The enthalpy change has the symbol _______.

• ΔH

• ΔS

• ΔG

• ΔE

Many chemical reactions involve the ______ of energy – the enthalpy decreases. (Fill in the blank)

• release

• absorption

• storage

• conversion

Look at the image of burning logs. Is energy being released or supplied in this chemical reaction?

• Energy is being released.

• Energy is being supplied.

Fill in the blank: Exothermic reactions cause a temperature ______ in the surrounding.

• rise

• fall

• stagnation

• loss

Fill in the blank: ΔH – the change in enthalpy (heat energy) is ________ in an exothermic reaction.

• negative

• positive

• zero

• undefined

Which of the following is an example of an exothermic reaction?

• Photosynthesis

• Neutralization

• Melting of ice

• Evaporation