Energetics

Question 1

What are:

Exothermic reactions

Answer 1

Reactions which release heat to the surroundings

Question 2

What are:

Reactions that take in heat from the surroundings

Answer 2

endothermic

Question 3

Practice and what is in a:

Reaction profile

Answer 3

Chemical energy on y axis, Time on x axis, activation energy, a curve, energy of reactants and products, enthalphy change

Question 4

What are examples of:

Exo and endo thermic reactions

Answer 4

• Displacement, combustion, neutralisation
• Thermal decomposition

Question 5

What are uses of:

Endo and exo thermic reactions

Answer 5

Exothermic:
Hand warmers, self-heating cans
Endothermic:
cold packs

Question 6

What is the equation for:

Enery change

Answer 6

delta Q = mc delta T
where m is mass of liquid, c is specific heat capacity and t is temperature change

Question 7

What is the equation for:

Enthalpy change

Answer 7

delta H = Q / mol
unit: Kj/mol
Symbol: + if endo - if exo

Question 8

Why is:

A bomb calirometer better than a normal calirometer

Answer 8

bomb calirometer has a large supply of oxygen, minimal heat loss to surroundings through insulation, food is set alight by wires, not a flame

Question 9

How to do:

Bond energy calculations

Answer 9

Breaking is endothermic
Making is exothermic
bendomexo, energy change = break - make