5.1 Measuring energy changes

Question 1

Define enthalpy

Answer 1

ENTHALPY: heat content of a system

Question 2

Where is enthalpy stored?

Answer 2

In bonds and intermolecular forces as potential energy

Question 3

Endothermic vs exothermic

Answer 3

Endothermic: E transfer from surrounding ti the system

Exothermic: E transfer from the system to the surrounding

Question 4

Standadr enthalpy change conditions

Answer 4

• 100 kPa
• conc 1 mol/dm3
• substances in their standard states

Question 5

Define specific heat capacity

Answer 5

SPECIFIC HEAT CAPACITY: property of a substance which gives the heat needed to increase the temoerature on the substance by 1K

Question 6

Heat change equation

Answer 6

q = m x c x ΔT

m= kg

c=J/gK

ΔT=K

q=kJ

Question 7

Tendencies of enthalpy change in reactions

Answer 7

Chemicals change to recuse their enthalpy - relatively more stable - if increase in entropy - increase enthalpy (gases)

Question 8

Define standardr enthalpy change of combustion

Answer 8

ENTHALPY OF COMBUSTION: enthalpy change for the complete combustion of 1 mol of substance under its standard state in excess ozygen in standard conditions

Question 9

Describe calorimeter

Answer 9

Question 10

Describe polysteryne cup

Answer 10