Chemistry Labs

International Chemistry Olympiad · 1970

Problems

  1. Problem 1An amount of 23 g of a gas (density ρ=2.05\rho = 2.05 g dm−3^{-3} at STP) when burned gives 44 g of carbon dioxide and 27 g of water. What is the structural formula of the gas (compound)?Solutions: 1
  2. Problem 4An alloy consists of rubidium and one of the other alkali metals. A sample of 4.6 g of the alloy, when allowed to react with water, liberates 2.241 dm3^3 of hydrogen at STP. (a) Which alkali metal is the component of the alloy? (b) What is the composition of the alloy in % by mass? Relative atomic masses: Ar(Li)=7A_r(\text{Li}) = 7; Ar(Na)=23A_r(\text{Na}) = 23; Ar(K)=39A_r(\text{K}) = 39; Ar(Rb)=85.5A_r(\text{Rb}) = 85.5; Ar(Cs)=133A_r(\text{Cs}) = 133.Solutions: 1