Chapter 1 2024/2025

i. Determine the relative atomic mass of zirconium.  

[3 Marks]

ii. Write the isotopic notation when zirconium atom undergoes ionisation by losing four electrons.   

[1 Mark]

b) An amount of 12.915 g of an organic compound containing carbon, hydrogen and oxygen was burned in excess oxygen. Analysis of the combustion revealed 18.942 g of carbon dioxide and 7.749 g of water were formed. Determine the empirical formula of the compound. 

[5 Marks]  

c) A reagent bottle contains a concentrated sulphuric acid solution with 98% by mass and a density of 1.83 gmL-1. Calculate the molarity of the acid  

[4 Marks]  

d) Potassium chlorate reacts with sulphur dioxide in an acidic medium according to the equation below. Balance the reaction equation by using ion-electron method 

  ClO3- + SO2 →  SO42- + Cl- 

[3 Marks]  

i. Calculate the mass of Si3N4 produced when 20.00 g of Si and 15.00 g on N2 are reacted. .  

[4 Marks]

ii. Determine the percentage yield if 24.75 g of Si3N4 is obtained in this reaction.  

[2 Marks]