You are provided with:

• Aqueous sulphuric (VI) acid labelled solution A.
• Solution B containing 10.4g per litre of potassium carbonate.
• A clean piece of magnesium ribbon.
• Methyl orange indicator.

You are required to determine the:

i) Concentration of solution A

ii) Rate of reaction between magnesium and sulphuric (VI) acid – solution A, at different concentration.

Procedure A

• Using a measuring cylinder, place 25.0cm³ of solution A into a 250ml volumetric flask.

• Add distilled water to make 250cm³ of solution. Label this solution C.

• Place solution C in a burette.

• Using a pipette and pipette filler place 25.0cm³ of solution B into a conical flask.

• Add 2 drops of methyl orange indicator provided and titrate with solution C.

• Record your results in table I below.

• Repeat the titration two more times and complete table I. (3 marks)

Table I.

a) Calculate:

i) Average volume of solution C used . (1 mark)

ii) Concentration of potassium carbonate in solution B (C = 12.0, O = 16.0, K = 39.0) (1 mark)

iii) Concentration of sulphuric (VI) acid in solution C. (1½ marks)

iv) Concentration of sulphuric (VI) acid in solution A (1½ marks)

Procedure B

• Label five test tubes 1, 2, 3, 4 and 5.

• Empty the burette and fill it with solution A.

• From the burette, place 10cm³ of solution A into test tube number 1. From the same burette, place 9cm³ of solution A into test tube number 2. Repeat the process for test tube numbers 3, 4 and 5 as shown in table II below.

• Using a 10ml measuring cylinder, measure 1cm³ of distilled water and add it to test tube number 2. Repeat The process for test-tube numbers 3, 4 and 5 as shown below.

• Cut out five pieces exactly 1cm long of the magnesium ribbon.

• Transfer all the solution in test tube number 1 into a clean 100ml beaker provided. Put one piece of the magnesium ribbon provided. Put one piece of the magnesium ribbon into the beaker and immediately start a stopwatch.

• Swirl the beaker gently to ensure the magnesium is always inside the solution.

• Record in table II below the time taken in seconds for magnesium ribbon to disappear.

• Pour away the final contents of the beaker and rinse it with water.

• Repeat the procedure from (iv) for each of the remaining test tube numbers 2, 3, 4 and 5 and complete the table II

b) Table II

i) Plot a graph of volume of solution A added (y –axis) against rate of reaction $\frac{1}{Time}$ (3 marks)

ii) What is the relationship between the concentration of solution A and the rate of reaction? Explain. (2 marks)

You are provided with solid Z carry out the test below to identify the anion and cation present

a) Put a spatula endful of solid Z in the boiling tube. Add about 10cm³ of distilled water.

Divide the solution into 3 portions.

i) To the first portion add NaOH until in excess

ii) To the second portion add NH₄OH drop wise until in excess.

b) Using a metallic spatula, scoop a little of solid Z. Place it in a non-luminous flame of a Bunsen burner.

c) i) To the third portion add acidified Ba(NO₃)_2(aq)

ii) To a spatula endful of solid Z add 2M HCl_(aq) and warm place a chromate paper at the mouth of the test tube

You are provided with substance K. Carry out the test below and record your observations and inferences in the table below.

a) Scoop a little of substance K with a clean spatula and place it at the hottest part of the non – luminous flame.

b)i) Add about 10cm³ of distilled water to the remaining solid K and divide it into 4 portions.

i) To the first portion add 3 drops of acidified potassium dichromate (VI).

ii) To the second portion add 3 drops of bromine water.

iii) To the third portion add 2 – 3 drops of universal indicator and determine the pH of the solution.

iv) To the fourth portion add a spatulaful of sodium carbonate.