Chemistry · Paper 2B · 2014
5 questions 🇹🇿 NECTA ✓ Official NECTA answersChemistry · Paper 2B · 2014
5 questions
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During a practical session, you are provided with two solutions: N1, a solution of ethanoic acid of unknown concentration N2, a solution of sodium hydroxide containing 4.0 g of NaOH per dm³ Using phenolphthalein as an indicator, your task is to determine the concentration of N1 by titrating it against N2. Instructions: Fill the burette with N1 Use a pipette to transfer 25.0 cm³ of N2 into a conical flask Add two drops of phenolphthalein and titrate until the colour changes
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In a reaction kinetics experiment, you are provided with: 0.1 M potassium iodide solution labeled P1 0.1 M hydrogen peroxide solution labeled P2 0.1 M sulfuric acid labeled P3 Starch solution You are instructed to mix equal volumes of P1, P2, and P3 in a beaker and add starch solution immediately. The time taken for a blue-black colour to appear is recorded. The experiment is repeated at different temperatures: 30°C, 40°C, 50°C, 60°C, and 70°C.
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You are given a sample of a salt coded X. Perform the following tests to determine the cation and anion in the salt: Procedure: (a) Observe and describe the physical appearance of the salt X. (b) Heat a small amount in a dry test tube and note any changes. (c) Dissolve the salt in water and divide the solution into three portions. (d) To the first portion, add aqueous sodium hydroxide dropwise, then in excess. (e) To the second portion, add aqueous ammonia dropwise, then in excess. (f) To the third portion, add barium chloride followed by dilute HCl. (g) To another portion, add silver nitrate followed by dilute nitric acid.
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