CC8b C1.47 Explain the law of 1) Show the formation of Students investigate the Take the students Conservation of conservation of mass applied a yellow precipitate of decomposition of copper through worked mass to: lead iodide by pouring carbonate. examples one step at a a a closed system including a small amounts of lead The expected percentage mass time. precipitation in a closed flask nitrate and potassium of copper oxide is 64.4% of the b a non-enclosed system iodide solutions in a mass of copper carbonate used. Digital Calculating including a reaction in an boiling tube. The final Students can be asked why masses of reactants open flask that takes in or mass should be the sum their values are different to this and products gives out a gas of the two initial masses. and how they can improve the presentation C1.48 Now add dilute experiment. If their value is Calculate masses of hydrochloric acid to lower (most likely), they reactants and products from marble chips in a boiling probably did not heat the tube balanced equations, given tube and ask the for long enough. They could the mass of one substance students what has improve the experiment by C1.49 Calculate the concentration happened to the mass. heating the tube again, cooling of solutions in g dm-3 This leads on to gases and re-weighing and repeating having mass and the this until two mass mass decreases because measurements are the same. the gas escapes from the This technique is called heating open boiling tube. to constant mass. Equipment: 2 x 100 cm3 glass beaker, 2 Equipment: For each group: boiling tubes, boiling Bunsen burner, heat resistant tube rack, electronic mat, mineral wool, test tube, balance, eye protection, test tube holders, a few grams lead nitrate solution of copper carbonate. (about 40 cm3 of 0.5 mol Students need access to an dm-3), potassium iodide electronic balance. solution (about 40 cm3 of 0.5 mol dm-3), hydrochloric acid (about
CC8b Conservation of mass C1.47 C1.48 C1.49 Explain the law of conservation of mass applied to: a a closed system including a precipitation in a closed flask b a non-enclosed system including a reaction in an open flask that takes in or gives out a gas Calculate masses of reactants and products from balanced equations, given the mass of one substance Calculate the concentration of solutions in g dm-3 1) Show the formation of a yellow precipitate of lead iodide by pouring small amounts of lead nitrate and potassium iodide solutions in a boiling tube. The final mass should be the sum of the two initial masses. Now add dilute hydrochloric acid to marble chips in a boiling tube and ask the students what has happened to the mass. This leads on to gases having mass and the mass decreases because the gas escapes from the open boiling tube. Equipment: 2 x 100 cm3 glass beaker, 2 boiling tubes, boiling tube rack, electronic balance, eye protection, lead nitrate solution (about 40 cm3 of 0.5 mol dm-3), potassium iodide solution (about 40 cm3 of 0.5 mol dm-3), hydrochloric acid (about Students investigate the decomposition of copper carbonate. The expected percentage mass of copper oxide is 64.4% of the mass of copper carbonate used. Students can be asked why their values are different to this and how they can improve the experiment. If their value is lower (most likely), they probably did not heat the tube for long enough. They could improve the experiment by heating the tube again, cooling and re-weighing and repeating this until two mass measurements are the same. This technique is called heating to constant mass. Equipment: For each group: Bunsen burner, heat resistant mat, mineral wool, test tube, test tube holders, a few grams of copper carbonate. Students need access to an electronic balance. Take the students through worked examples one step at a time. Digital Calculating masses of reactants and products presentation
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