Chemistry Labs

International Chemistry Olympiad · 1969

Problems

  1. Problem 1An amount of 20 g of potassium sulphate was dissolved in 150 cm3^3 of water. The solution was then electrolysed. After electrolysis, the content of potassium sulphate in the solution was 15 % by mass. What volumes of hydrogen and oxygen were obtained at a temperature of 20 °C and a pressure of 101 325 Pa?Solutions: 1
  2. Problem 3A 10 cm3^3 sample of an unknown gaseous hydrocarbon was mixed with 70 cm3^3 of oxygen and the mixture was set on fire by means of an electric spark. When the reaction was over and water vapour was liquefied, the final volume of gases decreased to 65 cm3^3. This mixture then reacted with a potassium hydroxide solution and the volume of gases decreased to 45 cm3^3. What is the molecular formula of the unknown hydrocarbon, all volumes being measured at standard temperature and pressure (STP)?Solutions: 1