You are provided with the following: Solution A: 0.05 M sodium hydroxide solution Solution B: A diprotic acid H₂X of unknown concentration Phenolphthalein indicator (a) Pipette 25.0 cm³ of solution B into a clean conical flask. Add 2–3 drops of phenolphthalein and titrate against solution A taken in a burette. Repeat the titration to obtain three consistent readings. (b) Record the initial and final burette readings for each titration in a well-labeled table and calculate the volume of solution A used. (c) Determine the average volume of solution A used in the titration. (d) Write a balanced chemical equation for the neutralization reaction. (e) Calculate the number of moles of sodium hydroxide used in the average titration. (f) Using your results, calculate the concentration of solution B in mol/dm³. (g) If 1.89 g of acid H₂X was used to prepare 250 cm³ of solution B, calculate the molar mass of the acid. (h) Identify the likely element X in H₂X if it is a common inorganic element.

1. Pipette 25.0 cm³ of solution B into a clean conical flask. Add 2–3 drops of phenolphthalein and titrate against solution A taken in a burette. Repeat the titration to obtain three consistent readings. (0 alama)
2. Perform the titration, record readings, and determine the average volume of solution A. (4 alama)
3. Record the initial and final burette readings for each titration in a well-labeled table and calculate the volume of solution A used. (0 alama)
4. Write a balanced chemical equation for the neutralization reaction. (1 alama)
5. Calculate the number of moles of sodium hydroxide used in the average titration. (2 alama)
6. Determine the average volume of solution A used in the titration. (0 alama)
7. Using your results, calculate the concentration of solution B in mol/dm³. (3 alama)
8. If 1.89 g of acid H₂X was used to prepare 250 cm³ of solution B, calculate the molar mass of the acid. (3 alama)
9. Identify the likely element X in H₂X if it is a common inorganic element. (2 alama)

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You are provided with: T1: Sodium thiosulphate solution (20 g/dm³) T2: Dilute hydrochloric acid (1.0 M) T3: Distilled water A stopwatch, a white paper marked “X”, and other necessary materials (a) Place the paper marked “X” on the bench and put a clean 50 cm³ beaker on top. Mix volumes of T1 and T3 as shown below. Then quickly add 10 cm³ of T2, start the stopwatch immediately and record the time taken for the mark “X” to disappear. Experiment Volume of T1 (cm³) Volume of T3 (cm³) Volume of T2 (cm³) 1 2 8 10 2 4 6 10 3 6 4 10 4 8 2 10 (b) Record the time taken for the cross to disappear in each case. (c) Complete the table by calculating the rate of reaction using 1/t for each experiment. (d) Plot a graph of rate of reaction (1/t) against volume of T1 used. (i) Describe the shape of your graph and what it suggests about the relationship between rate and concentration. (ii) State the order of the reaction with respect to sodium thiosulphate. (iii) Write the balanced ionic equation for the reaction that takes place. (iv) State the name of the substance responsible for the cloudiness during the reaction. (v) Suggest one way the experiment can be improved to determine the order with respect to hydrochloric acid.

1. Place the paper marked “X” on the bench and put a clean 50 cm³ beaker on top. Mix volumes of T1 and T3 as shown below. Then quickly add 10 cm³ of T2, start the stopwatch immediately and record the time taken for the mark “X” to disappear. (0 alama)
2. Perform the experiment and record the time taken for the cross to disappear in each case. (3 alama)
3. Complete the table by calculating the rate of reaction using 1/t for each experiment. (2 alama)
4. Record the time taken for the cross to disappear in each case. (0 alama)
5. Plot a graph of rate of reaction (1/t) against volume of T1 used. (4 alama)
6. Describe the shape of your graph and what it suggests about the relationship between rate and concentration. (2 alama)
7. State the order of the reaction with respect to sodium thiosulphate. (1 alama)
8. Write the balanced ionic equation for the reaction that takes place. (2 alama)
9. State the name of the substance responsible for the cloudiness during the reaction. (1 alama)
10. Suggest one way the experiment can be improved to determine the order with respect to hydrochloric acid. (2 alama)

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You are provided with a white crystalline solid labeled Sample W. Carry out the following tests and record your observations and inferences. (a) Observe the physical appearance of the sample. (b) Test the solubility of the sample in cold water. (c) Add a few drops of dilute hydrochloric acid to a small portion of W in a test tube. (d) Add concentrated sulphuric acid to a fresh portion of W. (e) Perform a flame test using a platinum wire dipped in the solid. (f) To a small amount of W, add aqueous sodium hydroxide dropwise and then in excess. (g) To another portion, add aqueous ammonia dropwise and then in excess. (h) Record your observations and write appropriate inferences in a clearly structured table. (i) Identify the cation and the anion present in Sample W. (j) Write two balanced chemical equations to support your identification of the ions present.

1. Carry out the specified tests on Sample W and record observations. (7 alama)
2. Record your observations and write appropriate inferences in a clearly structured table. (3 alama)
3. Identify the cation and the anion present in Sample W. (3 alama)
4. Write two balanced chemical equations to support your identification of the ions present. (2 alama)

Boresha ili kuona majibu ya mfano.