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SMART LEARNING GURU TUITION CENTRE
SECONDARY THREE CHEMISTRY
CHAPTER 13 : OXIDATION AND REDUCTION
ASSIGNMENT 1 (FUNDAMENTAL QUESTIONS)
Name : __________________________(
Class : 3 (
1.
)
Grade :
)
Date
Fill in the blanks in the following table:
No
Process in terms of
1
Oxygen
2
Hydrogen
3
Electrons transfer
4
Oxidation state / number
: ____________
[4]
Oxidation Reaction
Reduction Reaction
2.
For each of the following reaction, identify whether it is an oxidation or reduction
reaction, by circling the correct answer. Give a reason for your answer.
[12]
(a)
The conversion of copper to copper (II) oxide.
Oxidation / Reduction
________________________________________________________________________
(b)
The conversion of ethene, C2H4 to ethane C2H6.
Oxidation / Reduction
________________________________________________________________________
(c)
The conversion of ammonia to nitrogen.
Oxidation / Reduction
________________________________________________________________________
(d)
The conversion of sulfur dioxide to sulfur trioxide. Oxidation / Reduction
________________________________________________________________________
(e)
The conversion of copper(II) ions to copper.
Oxidation / Reduction
________________________________________________________________________
(f)
The conversion of bromide ions to bromine molecules. Oxidation / Reduction
________________________________________________________________________
Sec 3 Chemistry 2011
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3.
Calculate the oxidation number of the following elements.
(a) manganese in MnO2
(b) sulfur in H2S
(c) vanadium in NH4VO3
(d) chromium in Cr2O72-
(e) iron in FeCl3
(f) aluminium in AlF63-
4.
(a)
(b)
[6]
IO3- + 5I- + 6H+  3I2 + 3H2O
The reaction of iodate (V) ions with iodide in the presence of acid is shown below.
What are oxidation numbers of
(i) oxygen in IO3- and
(ii) iodine in IO3[2]
What changes occurs in the oxidation number of iodine in the reaction, in (i) I- and (ii)
IO3-?
[2]
________________________________________________________________________
________________________________________________________________________
(c)
Hence, which ion is oxidize?
[1]
________________________________________________________________________
5.
Circle the reducing agent in the following reactions. Explain your answers.
Sec 3 Chemistry 2011
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[4]
(a)
S + O2  SO2
________________________________________________________________________
(b)
2Fe + 3Cl2  2FeCl3
________________________________________________________________________
6.
Circle the oxidising agent in the following reactions. Explain your answers.
(a)
CuSO4 + Zn  ZnSO4 + Cu
[4]
________________________________________________________________________
(b)
Fe2O3 + 3CO  2Fe + 3CO2
________________________________________________________________________
7.
Study the following reactions carefully and then identify the reagents that act as oxidizing
agents or reducing agents. Write your answers in the table provided.
[3]
Reaction
(a)
(b)
(c)
(a)
(b)
(c)
Oxidising Agent
Reducing Agent
Aqueous ammonium persulfate, (NH4)2S2O8, is a colourless solution. When aqueous
ammonium persulfate is added to aqueous potassium iodide at room temperature, the
solution turns yellow and turns brown.
When hydrogen peroxide is added to a mixture of potassium dichromate and dilute
sulfuric acid, the colour changes from orange to green.
When solid sodium nitrite is added to potassium manganate (VII) and dilute sulfuric acid,
the solution turns from purple to colourless.
Comments from teacher:
Sec 3 Chemistry 2011
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