Chemistry Labs

International Chemistry Olympiad · 1972

Problems

  1. Problem 3A volume of 200 cm3^3 of a 2-normal sodium chloride solution (ρ=1.10\rho = 1.10 g cm−3^{-3}) was electrolysed at permanent stirring in an electrolytic cell with copper electrodes. Electrolysis was stopped when 22.4 dm3^3 (at STP) of a gas were liberated at the cathode. Calculate the mass percentage of NaCl in the solution after electrolysis. Relative atomic masses: Ar(H)=1A_r(\text{H}) = 1; Ar(O)=16A_r(\text{O}) = 16; Ar(Na)=23A_r(\text{Na}) = 23; Ar(Cl)=35.5A_r(\text{Cl}) = 35.5; Ar(Cu)=64A_r(\text{Cu}) = 64.Solutions: 1
  2. Problem 5Only one product was obtained by the reaction of bromine with an unknown hydrocarbon. Its density was 5.207 times as great as that of the air. Determine the structural formula of the unknown hydrocarbon. Relative atomic masses: Ar(H)=1A_r(\text{H}) = 1; Ar(C)=12A_r(\text{C}) = 12; Ar(Br)=80A_r(\text{Br}) = 80.Solutions: 1