Practical Chemistry – Physical (PC)

Phenolphthalein is used as an indicator for the titration of sodium hydroxide solution against a standard solution of oxalic acid. The colour change that is observed at an alkaline pH close to the equivalence point during this titration is :

1. pink to colourless
2. pinkish red to yellow
3. colourless to pink
4. yellow to pinkish red

Which indicator is used in the titration of sodium hydroxide against oxalic acid and what is the colour change at the end point?

1. Phenolphthalein, pink to yellow
2. Alkaline KMnO4, colourless to pink
3. Phenolphthalein, colourless to pink
4. Methyl orange, yellow to pinkish red colour

The absolute enthalpy of neutralisation of the reaction : MgO(s) + 2HCl(aq) MgCl2(aq) + H2O(l) will be

1. -57.33 kJ mol-1
2. greater than -57.33 kJ mol-1
3. less than -57.33 kJ mol-1
4. 57.33 kJ mol-1