Energetics

Question 1

What is exothermic?

Answer 1

chemical reactions in which heat energy is given out

Question 2

What is exothermic?

Answer 2

chemical reactions in which heat energy is taken in

Question 3

What is activation energy?

Answer 3

the minimum amount of energy the reactant particles need to collide with each other and react

Question 4

Is activation energy needed in exothermic reactions, why?

Answer 4

although exothermic reactions release energy, they need some activation energy to get the reaction started

Question 5

What are some examples of exothermic reactions?

Answer 5

combustion, neutralisation, oxidisation reactions

Question 6

What are bond energies?

Answer 6

the amount of energy needed to break one mole of a particular covalent bond

used to determine whether a reaction is exothermic/endothermic

Question 7

What kind of reaction is breaking bonds?

Answer 7

endothermic, requires energy from surrounding to break the bond

Question 8

What is bond formation?

Answer 8

the amount of energy released to make one mole of a covalent bond

Question 9

What kind of reaction is bond formation?

Answer 9

exothermic, energy released to form the bond

Question 10

What is the formula for molar enthalpy change?

Answer 10

ΔH = Q/moles

ΔH is the molar enthalpy change
Q is the heat energy (kJ)

Question 11

What is the molar enthalpy change?

Answer 11

the energy required to break bonds minus the energy released by forming bonds, if the value is negative the reaction is exothermic, if the value is positive the reaction is endothermic