Calorimetry

Question 1

What can you use calorimetry for?

Answer 1

To find out how much heat is given out by measuring a temperature change

Question 2

How do you find the enthalpy of combustion of a flammable liquid?

Answer 2

You burn the liquid inside some apparatus called a calorimeter. As the fuel burns, it heats the water. You can work out the heat energy absorbed by the water if you know the mass of the water, the temperature change and the specific heat capacity of the water

Question 3

Why is it hard to get an accurate result in calorimetry?

Answer 3

1. Heat loss to surroundings

2. Incomplete combustion

Question 4

What reactions can calorimetry be used to find enthalpy changes for?

Answer 4

Calorimetry can be used to calculate enthalpy changes for reactions that happen in solution - such as neutralisation, dissolution (dissolving) or displacement

Question 5

How do you figure out masses of solutions

Answer 5

You can assume all solutions have the same mass as water

Question 6

How do you use a graph of you calorimetry results to calculate an accurate temperature change?

Answer 6

1. During the expreiment, record the temperature at regular intervals, starting a couples of minutes before starting the reaction
2. Plot a graph of results. Draw two lines of best fit, one before the reaction started and one through the points after the reaction started
3. Extend both lines so the pass before the reaction started
   The distance between the two lines at the time of the reaction starting is the accurate temperature change for the reaction

Question 7

What is the equation to calculate an enthalpy change from a calorimetry experiment?

Answer 7

q = m c deltaT … Where,

q = heat lost or gained (in joules)
m = mass of solution, or water (in grams)
c = specific heat capacity of water
delta T = change in temperature (in Kelvin)

Question 8

How do you calculate Kelvin from C

Answer 8

Kelvin = C + 273