Get premium membership and access revision papers, questions with answers as well as video lessons.
Borabu Masaba District Mock-Chemistry Paper 3 Question Paper
Borabu Masaba District Mock-Chemistry Paper 3
Course:Secondary Level
Institution: Mock question papers
Exam Year:2012
Name………………………………………………………. Index No…………………/…….
School……………………………………………………… Date ………………………….…
Candidate’s Signature…………
233/3
CHEMISTRY
Paper 3
JULY/ AUGUST 2012
Time: 2 ¼ Hours
BORABU-MASABA DISTRICTS JOINT EVALUATION TEST– 2012
Kenya Certificate of Secondary Education (K.C.S.E)
233/3
CHEMISTRY
Paper 3
JULY / AUGUST 2012
Time: 2 ¼ Hours
INSTRUCTIONS TO CANDIDATES
1. Write your name and index number in the spaces provided above.
2. Sign and write the date of the examination in space provided.
3. Answer ALL the questions in the spaces provided in the question paper.
4. You are NOT allowed to start working with the apparatus for the first 15 minutes of the 2 ¼ hours allowed for this paper. This time is to enable you to read the question paper and make sure you have all the chemicals and apparatus that you may need.
5. All working MUST be clearly shown where necessary.
6. Mathematical tables and silent electronic calculators may be used.
7. The subject teacher will (in a separate room) perform the experiments for procedures I and II and submit the readings.
8. This paper consists of 8 printed pages. Candidates should confirm this.
FOR EXAMINER’S USE ONLY
QUESTION MAXIMUM SCORE CANDIDATE’S SCORE
1 25
2 10
3 5
TOTAL SCORE 40
This paper consists of 8 printed pages.
Candidates should check the question paper to ascertain that all pages are printed as indicated and that no question is missing
1. You are provided with
- Hydrochloric acid, Solution A.
- 0.30M Sodium hydroxide, Solution B
- Magnesium powder, Solid C.
You are required to determine:
- The concentration of hydrochloric acid in moles per litre.
- The molar enthalpy of hydrochloric acid with magnesium.
- The volume of hydrogen gas produced per unit time.
PROCEDURE I
Measure 50cm3 of solution A using a measuring cylinder and place it in 100 cm3 beaker, stir the solution gently with a thermometer and record its temperature after every thirty seconds, starting from Zero seconds. Record the readings in the table below. At exactly 120 seconds add all solid C at once, Stir the mixture gently with the thermometer and record the temperature of the mixture after every 30 seconds up to the 360th second and complete the table below.
Keep the solution for use in procedure (II)
Time (sec) 0 30 60 90 120 150 180 210 240 270 300 330 360
Temperature 0C X
(5 mks)
Questions.
(a) On the grid provided, plot a graph of temperature against time (seconds) (3 mks)
(b) From the graph determine the temperature change for the reaction (1 mk)
………………………………………………………………………………………………………………………………………………………………………………………………………………
(c) Calculate the heat change for the reaction between magnesium and hydrochloric acid given that C= 4.2 KJ/kg K-1, density of solution is 1.0g/cm3) (2 mks)
(d) Given that the mass of magnesium powder is 0.25g. Calculate
(i) The moles of hydrochloric acid, Solution A that reacted with magnesium.
(Mg = 24)
(ii) Heat evolved when one mole of hydrochloric acid, Solution A reacts with Magnesium powder, solid C. (1 mk)
(e) Calculate the volume of hydrogen gas produced per unit time at room temperature and pressure given that molar gas volume at r.t. p is 24,000cm3 (2 mks)
Procedure II
Place all the solution obtained in procedure I in a clean 100cm3 measuring cylinder. Add distilled water
to make 100cm3 of solution.
Transfer all the solution into a beaker and shake well. Label the resulting solution, Solution D.
Fill the burette with solution D. Pipette using a pipette filler 25.0 cm3 of solution B into a cornical flask. Add 2 – 3 drops of Phenolphthalein the titration two more times to complete the table II below.
Table II
I II III
Final burette reading (cm3)
Initial burette reading (cm3)
Volume of solution D used (cm3)
(5 mks)
(f) Determine the average volume of solution D used. (1 mk)
………………………………………………………………………………………………………………………………………………………………………………………………………………
(g) Calculate number of moles of sodium hydroxide, solution B that were used. (1 mk)
(h) Determine:-
(i) The number of moles of solution D reacted with 25cm3 of solution B. (1 mk)
(ii) The number of moles of hydrochloric acid in 100cm3 of solution D. (1 mk)
(iii) Using the results from d (i) and h (ii) above, calculate the total number of moles of
hydrochloric acid in 50cm3 of solution A. (1 mk)
(iv) The concentration of the original hydrochloric acid, solution A in moles per litre. (1 mk)
2. You are provided with solid E. Carry out the following tests and write your observations and inferences in the spaces provided.
(a) Place ¼ spatulaful of solid E in a test tube. Add about 10cm3 distilled water, and shake well. Divide the resulting solution into 4 portions of 2 cm3 each. To the 1st 2 cm3 portion add aqueous NaOH dropwise until in excess.
Observation Inference
(1 mk)
(1 mk)
(b) To portion 2 of the solution in a test-tube, add 1 cm3 of 0.5 M Sodium Sulphate solution.
Observation Inference
(1 mk)
(1 mk)
(c) Touch solid E with a wet metallic spatula and put the spatula in a non-luminous bunsen flame.
Observation Inference
(1 mk)
(1 mk)
(d) To portion three of the solution add 3 drops of diluted lead (II) nitrate solution.
Observation Inference
(1 mk)
(1 mk)
(e) To portion 4 of the solution, add 3 drops of dilute Barium Nitrate solution.
Observation Inference
(1 mk)
(1 mk)
3. You are provided with solid D. Carry out the following tests and write your observations and Inferences in the spaces provided.
Place the solid D on the piece of paper provided. Crush it into powder from using a clean and dry metallic spatula.
(a) Scoop ¼ spatula –ful of the solid and ignore it.
Observation Inference
( 1 mk)
( 1 mk)
(b) Place the rest of solid D in a boiling tube. Add 10cm3 of distilled water. Shake well, warm the mixture for 30 seconds and leave it to cool for 2 minutes.
Decant the mixture into a clean test tube and divide the solution into 4 portions of 2 cm3 each
(i) To portion one add 1 drop of acidified potassium Manganate (VII) solution and warm.
Observation Inference
( ½ mk)
( ½ mk)
(ii) To portion 2 add 1 drop of acidified potassium Chromate (VI) solution.
Observation Inference
( ½ mk)
( ½ mk)
(iii) to portion 4 add 2 drops of the universal indicator and test for the PH.
Observation Inference
( ½ mk)
( ½ mk)
More Question Papers
Popular Exams
Return to Question Papers