Page 136 - Chemistry

6. Filter funnel
7. Retort stand

1. You are provided with:
Solution J:xM ammonium iron(II)sulphate solution
Solution K: 0.02M potassium manganate (VII)solution
You are required to determine:
-The molarity, x of the ammonium iron (II) sulphate
- The amount of water of crystallisation, N in ammonium iron (II) sulphate
-The formula mass of ammonium iron (II)sulphate.

Procedure
The ammonium iron (II) sulphate, (NH 4) 2SO 4FeSO 4nH 2O solution provided was made by
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dissolving 8.5g of the salt in 50.0cm of dilute sulphuric(VI)acid, then making the solution
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to 250cm using distilled water.
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Fill the burette with solution K. Pipette 25cm of solution J and release into a conical flask.
Titrate J against K until the solution becomes permanent pink. Repeat two more times and
complete the table below;-
Table 1
I II III
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Final burrete racing (cm )
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Final burrete reading (cm )
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Volume of Solution K used (cm )

a) Calculate the average volume of solution K used
b) The number of moles of solution K reacting
c) Given that equation for the reaction is:
-
2+
+
MnO 4(aq) + 8H (aq) + 5Fe 2+ (aq) Mn 2+ (aq) + 5 Fe (aq) + 4H 2O (l)
Determine:
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i) The number of moles of iron (II) salt solution J in 25cm of the solution used
ii) The molarity of solution J
iii) The concentration of solution J in grams per litre
d) From your results in C (iii) above, determine:
i) the value of ―n‖ in the formula (NH 4) 2SO 4FeSO 4nH 2O.
(N=14, H= 1, S=32, O=16, Fe=56)
ii) Correct formula of the iron (II) salt
iii) The formula mass of the iron (II) salt

Q2.
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1. 120cm of solution R
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2. 80cm of solutions
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3. 250cm of tap water
4. 25ml or 50ml measuring cylinder
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5. 100cm glass beaker
6 5 x 5cm piece of white paper
7. Stop watch or clock.

2. You are provided with:
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i) Sodium thiosulphate containing 40g/dm solution R
ii) 2M hydrochloric acid solution S
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