This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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a) (i) Gas H is nitrogen (N_2). One use of nitrogen is to provide an inert atmosphere for packaging food. (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 as the experiment progresses are: • The black solid (copper(II) oxide) turns into a brown/pinkish-brown solid (copper metal). • Colourless liquid droplets (water) are observed in the cooler parts of the combustion tube or the connecting tube. (iv) The colour of the contents in the water trough changed from green to blue/purple. This is because unreacted ammonia gas, which is alkaline, dissolves in the water to form ammonium hydroxide. This alkaline solution turns the universal indicator blue or purple. (v) To calculate the mass of liquid Z (water) formed: Step 1: Calculate the moles of ammonia (NH_3) that reacted. We assume the reaction occurs at Room Temperature and Pressure (RTP), where the molar volume of a gas is 24000 cm^3/mol. Moles of NH_3 = Volume of NH_3Molar volume at RTP Moles of NH_3 = 480 cm^324000 cm^3/mol = 0.02 mol Step 2: Use the stoichiometry from the balanced equation to find the moles of water (H_2O) produced. From the equation 2NH_3(g) + 3CuO(s) → 3Cu(s) + 3H_2O(l) + N_2(g), the mole ratio of NH_3 to H_2O is 2:3. Moles of H_2O = (3)/(2) × Moles of NH_3 Moles of H_2O = (3)/(2) × 0.02 mol = 0.03 mol Step 3: Calculate the mass of water (liquid Z). The molar mass of H_2O is 2(1.0) + 16.0 = 18.0 g/mol. Mass of H_2O = Moles of H_2O × Molar mass of H_2O 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 📸