Ammonia reacts with copper(II) oxide. (i) Identify gas H. [1] (ii) Write a balanced chemical equation for the reaction in the combustion tube. [1] (iii) State two observations you would make in the co

i) Gas H is Nitrogen. One use of nitrogen is to provide an inert atmosphere for packaging food or in light bulbs. ii) The balanced chemical equation for the reaction in the combustion tube is: 2NH_3(g) + 3CuO(s) heat 3Cu(s) + 3H_2O(l) + N_2(g) iii) Two observations in the combustion tube: • The black solid (Copper(II) oxide) turns into a reddish-brown solid (Copper). • Colourless liquid droplets (water) are formed on the cooler parts of the tube. iv) The colour of the contents in the water trough would change from green to blue/purple. This is because any unreacted ammonia gas passing through the system would dissolve in the water, forming an alkaline solution. Universal indicator turns blue/purple in alkaline conditions. v) Step 1: Calculate the moles of ammonia. Assuming molar volume of gas at room temperature and pressure (RTP) is 24000 cm^3/mol. Moles of NH_3 = Volume of NH_3Molar volume at RTP = 480 cm^324000 cm^3/mol = 0.02 mol Step 2: Use the mole ratio from the balanced equation to find moles of water (liquid Z). From the equation 2NH_3(g) + 3CuO(s) → 3Cu(s) + 3H_2O(l) + N_2(g), the mole ratio of NH_3 : H_2O is 2:3. Moles of H_2O = Moles of NH_3 × (3)/(2) = 0.02 mol × (3)/(2) = 0.03 mol Step 3: Calculate the mass of water (liquid Z). Molar mass of H_2O = (2 × 1.0) + 16.0 = 18.0 g/mol. Mass of H_2O = Moles of H_2O × Molar mass of H_2O = 0.03 mol × 18.0 g/mol = 0.54 g The mass of liquid Z formed is 0.54 g. Send me the next one 📸