Measuring Enthalpy Changes (9.2)

Question 1

How do you convert between Kelvins and Degrees Celsius?

Answer 1

Degrees to Kelvins = +273

Kelvins to Degrees = -273

Question 2

What is the energy change calculation?

Answer 2

q = mc∆T

Question 3

What does c stand for in q= mc∆T?

Answer 3

Specific heat capacity

Question 4

What is always specific heat capacity in OCR A-Level questions

Answer 4

4.18 kjmol

Question 5

What does ∆T stand for in q= mc∆T?

Answer 5

The temperature change (final - inital)

Question 6

What does q mean in q= mc∆T?

Answer 6

Heat energy.

Question 7

What does m stand for in q= mc∆T?

Answer 7

mass

Question 8

What’s the rule about enthalpy changes of combustion?

Answer 8

Combustion is always exothermic so the value should always be negative

Question 9

Why are official enthalpy values usually bigger than experiments done in real time?

Answer 9

-Data book values are recorded with more sophisticated apparatus

-Heat loss to surroundings

-Conditions are unlikely to be standard when performed

Question 10

Is the solution in an aqueous solution considered the surroundings?

Answer 10

Yes, aqueous solutions are considered the immediate surroundings.