We made this post to highlight samples of the Specimens, alternatives to practical graphs, and calculations that were used in the Chem Practical Examination past questions and syllabus.<\/p>\n
Alternative WAEC GCE Chem Practical 2023.<\/strong><\/h3>\nPaper 3 (Alternative To Practical)<\/strong>
\nAnswer Three questions.<\/strong>
\nWrite your answers in the spaces provided.<\/strong><\/p>\n1. A student adds a known mass of magnesium ribbon to 100 cm3 of dilute hydrochloric acid (an excess) in the apparatus shown below. Hydrogen gas is evolved. The time taken to collect 48 cm3 of gas at room temperature and pressure is measured.<\/p>\n
![\"2017](\"https:\/\/unn-edu.info\/wp-content\/uploads\/2017\/09\/2017-gce-chemistry-practical.jpg\")
<\/p>\n
(a) (i) Name apparatus A.
\n(ii) Name apparatus B.
\n(b) (i) Calculate the number of moles of hydrogen in the 48 cm3 of gas.
\n[1 mole of any gas occupies 24 000 cm3 at room temperature and pressure.]<\/p>\n
(ii) Use the equation below to deduce the mass of magnesium used in the experiment to produce 48 cm3 of hydrogen at room temperature and pressure. [Ar : Mg, 24]
\nMg + 2HCl MgCl2 + H2
\n(c) Give a test for hydrogen gas.<\/p>\n
(d) What is the effect on the time taken to collect the same volume of gas if,
\n(i) large lumps of the same mass of magnesium are used instead of magnesium ribbon,
\n(ii) the reaction is carried out at a higher temperature?<\/p>\n
2. (a) A student investigates the electrolysis of aqueous copper(II) sulfate using graphite electrodes and the apparatus shown below.<\/p>\n
![\"\"](\"https:\/\/unn-edu.info\/wp-content\/uploads\/2017\/09\/waec-gce-chemistry-practical-2017.jpg\")
<\/p>\n
(i) What is observed at electrode R?
\n(ii) Construct the equation for the reaction taking place at electrode R.
\n(iii) When graphite electrodes are used a colour change is seen in the solution. What is this colour change? Explain why it happens.
\n(iv) When graphite electrodes are used, a gas is evolved at one of the electrodes. Name the gas and give a test for the gas.
\n(v) If the graphite electrodes are replaced with copper electrodes, no colour change is seen on the electrolysis of the solution. Explain why.<\/p>\n
(b) The student does more experiments using the apparatus in (a) with graphite electrodes
\nbut, in each case, using a different electrolyte.
\nComplete the table below.<\/p>\n
![\"waec](\"https:\/\/unn-edu.info\/wp-content\/uploads\/2017\/09\/waec-chem-practical.jpg\")
<\/p>\n
The details of the\u00a0WAEC Chem practical\u00a0drawings and answers will be made available to you candidates as soon as it is released. Keep following this page and make sure you bookmark this site for reference purposes.<\/p>\n
\nAnswer Three questions.<\/strong>
\nWrite your answers in the spaces provided.<\/strong><\/p>\n
1. A student adds a known mass of magnesium ribbon to 100 cm3 of dilute hydrochloric acid (an excess) in the apparatus shown below. Hydrogen gas is evolved. The time taken to collect 48 cm3 of gas at room temperature and pressure is measured.<\/p>\n
<\/p>\n
(a) (i) Name apparatus A.
\n(ii) Name apparatus B.
\n(b) (i) Calculate the number of moles of hydrogen in the 48 cm3 of gas.
\n[1 mole of any gas occupies 24 000 cm3 at room temperature and pressure.]<\/p>\n
(ii) Use the equation below to deduce the mass of magnesium used in the experiment to produce 48 cm3 of hydrogen at room temperature and pressure. [Ar : Mg, 24]
\nMg + 2HCl MgCl2 + H2
\n(c) Give a test for hydrogen gas.<\/p>\n
(d) What is the effect on the time taken to collect the same volume of gas if,
\n(i) large lumps of the same mass of magnesium are used instead of magnesium ribbon,
\n(ii) the reaction is carried out at a higher temperature?<\/p>\n
2. (a) A student investigates the electrolysis of aqueous copper(II) sulfate using graphite electrodes and the apparatus shown below.<\/p>\n
<\/p>\n
(i) What is observed at electrode R?
\n(ii) Construct the equation for the reaction taking place at electrode R.
\n(iii) When graphite electrodes are used a colour change is seen in the solution. What is this colour change? Explain why it happens.
\n(iv) When graphite electrodes are used, a gas is evolved at one of the electrodes. Name the gas and give a test for the gas.
\n(v) If the graphite electrodes are replaced with copper electrodes, no colour change is seen on the electrolysis of the solution. Explain why.<\/p>\n
(b) The student does more experiments using the apparatus in (a) with graphite electrodes
\nbut, in each case, using a different electrolyte.
\nComplete the table below.<\/p>\n
<\/p>\n
The details of the\u00a0WAEC Chem practical\u00a0drawings and answers will be made available to you candidates as soon as it is released. Keep following this page and make sure you bookmark this site for reference purposes.<\/p>\n