Questions will generally be based on the syllabus of the GCE Ordinary Level. 

Round 1: Sample questions

Question 1

Solution A comprises of three different compounds, namely ammonium hydroxide, n-Butyl alcohol, and ethyl alcohol. You are tasked to prepare solution A.

Calculate the volume of each reagent added to obtain 12.5 mL of solution A. [2m]

You are given the following information below:

i. Density: ammonium hydroxide [0.9 g/mL], n-Butyl Alcohol [0.8097 g/mL] and ethyl alcohol [0.789 g/mL]

ii. Molar Mass: ammonium hydroxide [35.05 g/mol], n-Butyl Alcohol [74.12 g/mol] and ethyl alcohol [46.07 g/mol]

iii. Number of moles: ammonium hydroxide [0.193 mol], n-Butyl Alcohol [0.038 mol] and ethyl alcohol [0.026 mol]

Question 2

Solution B comprises of two different compounds, namely Trisodium Phosphate and Sodium Acetate. You are tasked to prepare solution B.

Calculate the concentration (in mol/ L) of each reagent added to obtain 4000 mL of solution B in H2O. [2m]

You are given the following information below:

i. Mass: Trisodium Phosphate [200 g] and Sodium Acetate [150 g]

ii. Molar Mass: Trisodium Phosphate [163.94 g/mol] and Sodium Acetate [82.03 g/mol]

Question 3 (Open ended question)

What do you think could be the reasons for a deviation in the value from the Babcock method as compared to the manufacturer’s value? What are some of the experimental errors you might foresee in this experiment? [2m]

SLS Modules: