quiz 4[redox n thermo]

QUIZ 4 (REDOX AND THERMOCHEMISTRY)1. Definition of redox reaction:

OXIDATION REDUCTION1. Loss or gain of oxygen A substance gain oxygen [1]2. Loss or gain of hydrogen [1] A substance gains hydrogen3. Transfer of electrons A substances loses electrons [1]4. Change in oxidation number Increase in oxidation number [1]

2. Complete the table into:

Chemical reaction Substance oxidized

Substance reduced

Oxidizing agent

Reducing agent

i) Mg + CuO MgO + Cuii) H2S + Cl2 S + 2HCliii) 2Na + Cl2 2NaCliv) Mg + CuSO4 MgSO4 + Cu

3. Complete the following table to explain redox reactions in the three test tubes:

Displacement of Metal Change from iron(II) to iron(II) Displacement of Halogen

Experiment

Observation

Oxidizing agentReducing agentReduction half equationExplain reduction in terms of change in oxidation number

4. Redox reaction : Transfer of electron at a distance.Label anode and cathode for the given U-tube below.

Complete the table below by classifying the reagent given into oxidizing/reducing agent and state the observation:

Reagent Oxidizing/ Reducing

Agent Observation Reagent

Oxidizing/ Reducing

AgentObservation

Iron(II) sulphate

Bromine water

Acidified K2Cr2O7

Potassium bromide

Chlorine water

Acidified KMnO4

Potassium iodide

Reactive metal e.g

ZincIron(III)

sulphate

THERMOCHEMISTRY5. Complete the table below:

Heat of Reaction

Definition Thermochemicalequation

Ionic equation Energy level diagram

Heat of Precipitation

Pb(NO3)2 + Na2SO4

PbSO4 + 2NaNO3

∆H=-50.4kJmol-1

Heat of Displacement

Zn + CuSO4 ZnSO4 + Cu

∆H=-217 kJmol-1

Heat of Neutralisation

KOH + HNO3 KNO3 + H2O

∆H=-57kJmol-1

Heat of Combustion

C2H5OH + 3O2 2CO2 + 3O2

∆H=-1366kJmol-1

6. Draw the apparatus set-up to determine the heat of combustion of propanol [2m]

7. The table below shows the molecular formula and the hat of combustion of three types of alcoholAlcohol Molecular Formula Heat of Combustion/ kJmol-1

Methanol CH3OH 725Ethanol C2H5OH 1376

Propan-1-ol C3H7OH 2015

Explain why there are differences in the value of heat of combustion of the alcohols in the table [3m]………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

8. Question from Quiz 1 ….....................................................................................................................................................................................................................................................................................................................................................

9. Question from Quiz 2 ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………...

10. Question from Quiz 3…..………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………