energetics

Question 1

suggest one reason why enthalpy of combustion would be the same as the one calculated

Answer 1

same reaction/equation

Question 2

suggest one reason why standard enthalpy of combustion of hydrogen to differ slightly

Answer 2

slight difference in bond enthalpy values

Question 3

The student considered using a glass beaker on a tripod and gauze instead of the clamped copper calorimeter.
Suggest two disadvantages of using a glass beaker on a tripod and gauze.

Answer 3

disadvantage 1
- glass is a poorer conductor than copper

disadvantage 2
- tripod + gauze reduces heat transfer
- tripod/gauze fixed height above flame

Question 4

Suggest two reasons why the value of enthalpy of combustion from this experiment is
less exothermic than a data book value.

Answer 4

reason 1
- incomplete combustion

reason 2
- heat loss to surroundings

Question 5

Suggest one addition to this apparatus that would improve the accuracy of the
enthalpy value obtained

Answer 5

add lid

Question 6

the enthalpy change for this reaction is quite small. by reference to number and types of bonds broken, explain how this was predicted

Answer 6

• same number of bonds broken and made
• similar types of bonds broken and made