FINAL TEST AS/JAN2023/CHM421
UNIVERSITI TEKNOLOGI MARA
_________________________________________________________________________
TIME : 2 HOURS
_________________________________________________________________________
QUESTION1
a) Define the purpose of standardization.
(1 mark)
b) Back titration is required in some chemical analysis as shown in chemical equation
below.
2HNO3 + CaCO3 Ca(NO3)2 + CO2 + H2O
HNO3 + NaOH NaNO3 + H2O
Sketch the titration curve for the above titration.
(2 marks)
c) A 15 mL water sample was titrated with 15.20 mL 0.003 M EDTA to the endpoint under
pH 10.
i) Discuss briefly why titration should not be performed at pH more than 10.
(2 marks)
, FINAL TEST AS/JAN2023/CHM421
ii) Calculate the hardness (ppm) of water by determining the content of MgCO3 in
a water sample.
(4 marks)
iii) Identify the level of hardness of the water sample based on value obtain in cii).
(1 mark)
UNIVERSITI TEKNOLOGI MARA
_________________________________________________________________________
TIME : 2 HOURS
_________________________________________________________________________
QUESTION1
a) Define the purpose of standardization.
(1 mark)
b) Back titration is required in some chemical analysis as shown in chemical equation
below.
2HNO3 + CaCO3 Ca(NO3)2 + CO2 + H2O
HNO3 + NaOH NaNO3 + H2O
Sketch the titration curve for the above titration.
(2 marks)
c) A 15 mL water sample was titrated with 15.20 mL 0.003 M EDTA to the endpoint under
pH 10.
i) Discuss briefly why titration should not be performed at pH more than 10.
(2 marks)
, FINAL TEST AS/JAN2023/CHM421
ii) Calculate the hardness (ppm) of water by determining the content of MgCO3 in
a water sample.
(4 marks)
iii) Identify the level of hardness of the water sample based on value obtain in cii).
(1 mark)
