Chapter 2-DF1

Question 1

What is an enthalpy level diagram?

Answer 1

Show the energy change in the reaction

Question 2

What is the symbol for enthalpy change?

Answer 2

ΔH

Question 3

What does it mean if the enthalpy change is negative?

Answer 3

It is an exothermic reaction

Question 4

What does it mean if the enthalpy change is positive?

Answer 4

It is an endothermic reaction

Question 5

Where are the products and reactants on an energy level diagram for an exothermic reaction?

Answer 5

Reactants are higher than the products

Question 6

Where are the products and reactants on an energy level diagram for an endothermic reaction?

Answer 6

Reactants are lower than the products

Question 7

What are the standard conditions?

Answer 7

1 atmosphere
1 mol dm-3
298K - 25°C

Question 8

How do you convert from °C to K?

Answer 8

Add 273

Question 9

How would the standard state of neutralisation be shown?

Answer 9

ΔneutHθ298

Question 10

What is calorimetry?

Answer 10

Used to measure the enthalpy change of a reaction

Question 11

What is the equation used for calorimetry?

Answer 11

q=mcΔT

Question 12

What equation links moles, mass and Mr?

Answer 12

Moles = mass / Mr

Question 13

How do you work out the combustion of an enthalpy change in standard state?

Answer 13

ΔcHθ = q / moles

Question 14

How do we work out the enthalpy change of neutralisation?

Answer 14

energy transferred (J) =
mass of solution (g) × 4.18 (J g–1 K–1)× maximum temperature increase (K)
E = mc∆T
mols = vol in cm3/1000cm3 x conc moldm-3
divide the energy transferred by this to give the enthalpy change of neutralisation in kJ per mole of water.