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You are provided with;
- Aqueous sulphuric (VI) acid labeled solution A.
- Solution B containing 8.0g per litre of sodium carbonate
- A queous solution of substance C. You are required to determine the;
i) Concentration of solution A
ii) Enthalpy of reaction between sulphuric (VI) acid and substance C. A.
Using a pipette place 25.0cm3 of solution A into 250ml volumetric flask. Add distilled water to make 250cm3 of solution.
Label the solution as D.
Place solution D in a burette.
Clean the pipette and use it to place 25.0cm3 of solution B into a conical flask .
Add 2 drops of methyl orange indicator provided and titrate with solution D.
Record your results in table 1 .
Repeat the titration two more times and complete the table .
Calculate i) Average volume of D used. (1mk)
ii) Concentration of sodium carbonate in solution B. (Na=23; O=16; C=12) (1mk)
iii) Concentration of sulphuric (VI) acid in solution D (1mk)
iv) Concentration of sulphuric (VI) acid in solution A (1mk)
Label six test- tubes as 1,2,3,4,5 and 6.
Empty the burette and fill it with solution A. From the burette, place 2cm3 of solution A into test-tube number 1.
From the burette , place 4cm3 of solution A in test-tube number 2.
Repeat the process for test tube number 3,4,5 and 6 as shown in table 2
Clean the burette and fill it with solution C. From the burette, place 14cm3 of solution C into a boiling tube. Measure the initial temperature of solution C and record it in table 2. Add the contents of test-tube number 1 to the boiling tube containing solution C. Stir the mixture with the thermometer . Note and record the highest temperature reached in table 2. Repeat the process with other volumes of solution C given in table 2 and complete the table
b)i) Plot a graph of change in temperature ∆T (0C) against the volume of solution A (cm3) (3mks)
ii) From the graph, determine the
I. maximum change in temperature, ∆T (0C) (1mk)
II. Determine the volume of solution A required to completely with solution react C. (1mk)
I. Calculate the number of moles of sulphuric (VI) acid used. (1mk)
II. Determine the molar enthalpy of the reaction between sulphuric (VI) acid and substance C. (2mks)
You are provided with solid K. Carry out the following tests and write your observations and inferences, in the spaces provided.
a) Heat a spatula endfull of solid K in a boiling tube. Test any gases produced with both red and blue litmus papers.
b) Put a spatula end full of solid K in a boiling tube and then add a few drops of sodium hydroxide solution and heat. Test the gas produced using red and blue litmus papers.
c) Place the remaining portion of solid K in a test tube. Add about 10cm3 of distilled water and shake to dissolve. Divide the solution into four portions.
i) To the first portion, add sodium hydroxide solution dropwise till in excess.
ii) To the second portion, add ammonium hydroxide dropwise till in excess.
iii) To the third portion, add a few drops of dilute sulphuric (VI) acid.
iv) To the fourth portion, add a few drops of barium nitrate solution.
You are provided with solid Q. Carry out the tests below and record your observations and inferences in the spaces provided.
a) Place half a spatula of Q in a metallic spatula and burn in a non- luminous Bunsen flame. (2 marks)
Transfer the remaining solid Q into a boiling tube and add about 10cm3 of distilled water. Divide the resulting solution into 3 portions.
b) To the 1st portion, add a few drops of acidified potassium dichromate (VI) and warm.
c) To the 2nd portion, add a few drops of Bromine water and warm
d) To the 3rd portion, add a quarter spatula full of sodium hydrogen carbonate.