A second full 40-mark Paper 032 style practice paper with three questions — identifying an unknown salt, preparing copper(II) sulfate crystals, and electrolysis of copper(II) sulfate — with marks tagged for experimental skills and use of knowledge.
4 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Another forty marks, another three practicals. This paper tests the skills teachers look for in the SBA: reporting observations, preparing a pure salt and measuring electrolysis.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
3 questions; 40 marks: Q1 14, Q2 13, Q3 13.
Experimental Skills [XS] 30; Use of Knowledge [UK] 10.
Observation, inference; ionic equations; acid before barium.
Insoluble base in excess; filter; crystallise; dry.
Cathode gains copper; anode loses; constant current.
Quantity and unit in every heading.
2 h 10 min: about 3 minutes per mark.
Tick each point you earned and note missed skills.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (40 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [14 marks]
Solid A is a pale green crystalline salt which dissolves in water. When dilute sodium hydroxide is added dropwise to a solution of A, a dirty green precipitate forms which does not dissolve in excess and turns brown on standing. When dilute hydrochloric acid and barium chloride solution are added to another portion, a white precipitate forms.
(a) (a) Describe how the cation test with sodium hydroxide should be carried out. [4]
(b) (b) Draw a table with suitable headings for recording the tests. [3]
(c) (c) State three safety precautions for these tests. [3]
(d) (d) Identify the cation and anion in A. [2]
(e) (e) Write the ionic equation for the formation of the green precipitate. [1]
(f) (f) Explain why dilute acid is added before barium chloride in the test for sulfate. [1]
Question 2 [13 marks]
A student prepares pure dry crystals of copper(II) sulfate from copper(II) oxide and dilute sulfuric acid.
(a) (a) Describe the method, including a labelled diagram of the filtration stage. [6]
(b) (b) State why the copper(II) oxide is added in excess. [1]
(c) (c) State three precautions or steps to obtain pure, dry crystals. [3]
(d) (d) Write an equation for the reaction. [1]
(e) (e) State the colour of the solution and of the crystals. [1]
(f) (f) Name the type of reaction between an oxide and an acid. [1]
Question 3 [13 marks]
A student electrolyses copper(II) sulfate solution using copper electrodes at a constant current. The mass of the cathode is 1.20 g at the start and 1.36, 1.52, 1.68 and 1.84 g after 5, 10, 15 and 20 minutes.
(a) (a) Describe how the student sets up the apparatus and obtains the readings. [5]
(b) (b) Draw a table with suitable headings for the results. [2]
(c) (c) State what should be plotted and the shape of the graph. [3]
(d) (d) Write the half-equation for the reaction at the cathode. [1]
(e) (e) Describe what happens at the anode and to the colour of the solution. [1]
(f) (f) Calculate the mass of copper deposited in 20 minutes. [1]
Everything in this lesson is based on these parts of the CXC syllabus and papers.