Energetics

Question 1

What are the two reactions looked at?

Answer 1

Exothermic and Endothermic

Question 2

List all the characteristics of an exothermic reaction?

Answer 2

Temperature goes up
Heat energy moves out
Energy goes from chemical to thermal
∆H = negative

Question 3

List all the characteristics of an endothermic reaction?

Answer 3

Temperature goes down
Heat energy is taken in
Heat energy is taken out
Energy goes from chemical to thermal
∆H = positive

Question 4

What does ∆H stand for?

Answer 4

∆ - Change
H - Change in Chemical store

Question 5

In an exothermic graph which way does the arrow point up or down?

Answer 5

∆H arrow points down

Question 6

In an endothermic graph which way does the arrow point up or down?

Answer 6

∆H arrow points up

Question 7

What reaction is bond breaking?

Answer 7

Endothermic

Question 8

What reaction is bond formation

Answer 8

Exothermic

Question 9

Give the equation for specific heat capacity?

Answer 9

Q-MC∆T
M = mass of water
C = specific heat capacity - 4.2

Question 10

What is energy of water converted to and how is it done?

Answer 10

Converted to ∆H by dividing -Q by (moles x 1000)

Question 11

How would a combustion calorimetry test be carried out?

Answer 11

1.Weigh the burner at the start
2. Put 100cm cubed of water into the metal can
3. Measure waters starting temp
4. Allow water to be heated until the flame is extinguished
5. Measure final temp of water
6. Measure final mass of the burner

Question 12

How would you carry out a solution calorimetry test?

Answer 12

1. Use a polystyrene cup and put it into a glass beaker
2. Use a volumetric pipette and place copper sulphate solution in the cup
3. Measure initial temperature of solution
4. Weigh 1g of either Zn, Mg or Fe
5. Tip metal in cup and stir continuously
6. Measure max temp of solution

Question 13

Why is a polystyrene cup used in the solution calorimetry test?

Answer 13

As its an insulator and loses heat less