When 380 mg of potassium is added to 480 cm3 of water at 22 ∘C22\text{ }^\circ\text{C}22 ∘C under a pressure of 98.0 kPa, a reaction occurs producing a gas.
Write a balanced molecular equation for the reaction that occurs.
Calculate the volume, in cm3\text{cm}^3cm3, of the gas formed. (The gas constant R=8.31 J K−1 mol−1R = 8.31\text{ J K}^{-1}\text{ mol}^{-1}R=8.31 J K−1 mol−1, relative atomic mass Ar(K)=39.1A_r(\text{K}) = 39.1Ar(K)=39.1)
Calculate the concentration, in mol dm−3\text{mol dm}^{-3}mol dm−3, of potassium ions in the resulting solution.
79 exam-style questions on AQA A Level Chemistry Amount of substance, covering Relative atomic mass and relative molecular mass, The mole and the Avogadro constant, The ideal gas equation, Empirical and molecular formula, and Balanced equations and associated calculations. Each one has a worked solution and a mark scheme showing where the marks go.