Enthalpy (4)

Question 1

What does calorimetry allow you to do

Answer 1

Measure the amount of energy transferred in a chemical reaction

Question 2

What are the different types of calorimetry

Answer 2

Dissolving, Displacement, Neutralisation

And Combustion

Question 3

How do you measure the energy transferred in enthalpy reactions

Answer 3

Measure the temperatures at the beginning. Mix them together and measure the temperature of the solution at the end of the reaction (after)

Question 4

How can you lose less heat to the surroundings

Answer 4

Put the polystyrene cup into a beaker of cotton wool to give more insulation + put a lid on the cup

Question 5

You can lose less heat to the surroundings by putting the polystyrene cup into a beaker of cotton wool to give more _____________ + put a lid on the cup to reduce energy lost by ________________

Answer 5

Insulation

Evaporation

Question 6

Example of enthalpy reaction

Answer 6

Put 25cm3 of hydrochloric acid in a polystyrene cup and record the temperature of the acid.
Put 25cm3 of dilute sodium solution in a measuring cylinder and record its temperature.
Mix.
Take the temperature every 30 seconds and record the highest temperature it reaches

Question 7

To measure the amount of energy produced when a fuel is burnt, simply burn the fuel and use the flame to heat up some _________. This is _______________ calorimetry

Answer 7

Water

Combustion

Question 8

Combustion calorimetry uses a metal container, usually made of __________ because it conducts heat so well

Answer 8

Copper

Question 9

What is important to remember when heating up the water

Answer 9

To reduce draughts. Use a screen to act as a draught excluder

Question 10

Calorimetry - Combustion:
Put 50g of water in the copper can and record its temperature.
_________ the spirit burner and lid.
Put the spirit burner underneath the can and burn the wick. Heat the water stirring constantly until the temperature reaches about _____.
Put out the flame using the burner lid and measure the final temperature of the _________.
_________ the spirit burner and lid again
You can then use the temperature measurements you’ve taken to calculate the __________ change

Answer 10

Weigh
50°
Water
Weigh
Enthalpy

Question 11

How to calculate the heat heat energy transferred

Answer 11

Measure how much fuel you’ve burnt
Measure the temperature change of the water
You can now work out how much energy is supplied by each gram of fuel

Question 12

The specific heat capacity of water is ________ what does this mean.

Answer 12

4.2J/g/°C

So it takes 4.2 joules of energy to raise the temperature of 1g of water by 1°C