Energetics

Question 1

What is an Exothermic Reaction?

Answer 1

A reaction which releases energy, typically in the form of heat

(Although it can be in other forms, e.g glowsticks release light)

Question 2

What is an Endothermic Reaction?

Answer 2

A reaction which takes energy from is surroundings, typically resulting in a lower temperature. If there is no energy to fuel the reaction, it slows down or stops

Question 3

Why do Exothermic Reactions release energy?

Answer 3

The energy needed to break the bond is higher than needed to form the bond, so it releases that extra energy, in forms such as heat

Question 4

Why do Endothermic Reactions make the surroundings colder?

Answer 4

The energy needed to break the molecules bond is lower than it would be to form it again, resulting in energy being taken from the surroundings to fuel the forming of the bond.

Question 5

What are some examples of exothermic reactions?

Answer 5

• Combustion (Explosions and Fire :D)
• Freezing1
• Iron Rusting
• Condensation
• Respiration

1Freezing is an exothermic reaction because it loses heat to freeze

Question 6

Examples of a endothermic reaction

Answer 6

• Photosynthesis 1
• Instant Ice Pack thingy
• Melting & Evaporating

1Becuase it takes light from its surroundings to fuel the reaction

Question 7

How do we determine if the reaction is endothermic or exothermic?

Answer 7

If the overall energy change (ΔH) is more or less than 0.
ΔH is more than 0 = Endothermic
ΔH is less than 0 = Exothermic