A solution labeled Q1 is known to contain 0.05 mol/dm³ of sulfuric acid. Another solution labeled Q2 was prepared by dissolving 2.00 g of sodium hydroxide in 500 cm³ of water. You are required to determine the average volume of Q1 required to completely neutralize 25.0 cm³ of Q2 using phenolphthalein as the indicator. Instructions: Pipette 25.0 cm³ of Q2 into a conical flask Add 2 drops of phenolphthalein Titrate with Q1 from the burette Repeat to obtain consistent readings and calculate the average volume used (a) What colour change will be observed during the titration? (b) Write the balanced chemical equation for the reaction between Q1 and Q2. (c) Calculate the number of moles of NaOH in 25.0 cm³ of Q2. (d) Determine the volume of Q1 required to neutralize this amount of NaOH. (e) Calculate the average titre (assume it is 25.0 cm³). (f) Based on the above data, verify the concentration of Q1 and comment on whether the results are consistent.

1. What colour change will be observed during the titration? (2 mk)
2. Write the balanced chemical equation for the reaction between Q1 and Q2. (4 mk)
3. Calculate the number of moles of NaOH in 25.0 cm³ of Q2. (4 mk)
4. Determine the volume of Q1 required to neutralize this amount of NaOH. (6 mk)
5. Calculate the average titre (assume it is 25.0 cm³). (2 mk)
6. Based on the above data, verify the concentration of Q1 and comment on whether the results are consistent. (4 mk)

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You are provided with: 0.1 M sodium thiosulphate (R1) 0.1 M hydrochloric acid (R2) Distilled water, beaker, stopwatch, and a sheet marked with an “X” You are required to study the effect of changing the volume (and thus concentration) of R1 on the rate of reaction. Procedure: (i) Add 10 cm³ of R1 and 10 cm³ of R2 in a beaker over the marked “X” (ii) Record the time for the mark to disappear (iii) Repeat the procedure by diluting R1 with distilled water to get 8, 6, 4, and 2 cm³ while keeping total volume constant (a) Why does the “X” mark disappear during the experiment? (b) Complete the following table:

1. Why does the “X” mark disappear during the experiment? (5 mk)
2. Complete the following table: (25 mk)

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