COLLEGE OF ENGINEERING

SEMESTER II 2007/2008

CHEMISTRY LABORATORY WRITTEN TEST

PROGRAMME:FOUNDATION IN ENGINEERING

BACHELOR IN ENGINEERING

COURSE:CHEMISTRY LABORATORY

COURSE CODE:CHEF 111 / CHEB 111

DATE:MARCH 2008

DURATION: 1 HOUR

______

NAME: ______STUDENT ID.: ______

SECTION : ______INSTRUCTOR : ______

INSTRUCTIONS FOR CANDIDATES:

  1. There are twenty (20) multiple choice questions in this booklet. Answer all questions.
  2. There is only ONE best response to each question. Read all responses, choose the BEST one and circle it on the page. Then, shade the letter corresponding to that response in the answer sheet.
  3. No reference books, papers or mobile phones are allowed into the examination hall.
  4. You will submit only the answer sheet (Page9). Please make sure that you write your name, student ID, Lab Section and your instructor’s name on the answer sheet.

DO NOT OPEN THIS QUESTION PAPER UNTIL YOU ARE

INSTRUCTED TO DO SO

TABLE OF CONSTANTS
1 atm = 760 mmHg = 760 torr = 101,325 Pa
1 J = 1 kg. m2 / s2
Planck’s constant, h = 6.63 x 10-34J.s
Rydberg constant, RH = 2.18 x 10-18J. / Gas constant, R = 0.0821 L. atm / K. mol
Gas constant, R = 8.314 J / K. mol
Speed of light, c= 3.0 x 108 ms-1
Avogadro's number = 6.022 x 10 23 mol-1

This question paper has9 printed pages including this cover page.

  1. Statements below are NOT the general safety and laboratory rules,EXCEPT
  2. Food, drinks or smoking are allowed in the laboratory.
  3. Students should not be bothered with the location of fire extinguishers and the nearest exit.
  4. Students should identify chemicals by tasting the substance.
  5. Working bench must be clean and clear of any obstacles or flammable items.
  6. Broken glassware should be thrown into the sink.

1

  1. An empty graduated cylinder weights 45.9 g. The density of a liquid is 2.50 g/mL. If 20.0 mL of the liquid is added to the graduated cylinder what will be the total mass (in grams) of the cylinder and its contents?

1

  1. 95.9 g
  2. 8.0 g
  3. 50.0 g
  4. 53.8 g
  5. 58.0 g

1

  1. A crucible is known to weigh 24.3162 g. Three students in the class determine the weight of the crucible by repeated weighing on a simple balance. Using the following information, which student has done the most precise determination?

Student / Trial 1 / Trial 2 / Trial 3 / Trial 4 / Trial 5
A / 24.8 / 24.9 / 24.8 / 24.9 / 24.8
B / 24.8 / 24.0 / 24.2 / 24.1 / 24.3
C / 24.5 / 24.1 / 24.5 / 24.1 / 24.3
  1. Student B has done the most precise work.
  2. Student A has done the most precise work.
  3. Student C has done the most precise work.
  4. Both student B and C has done the most precise work.
  5. The students’ works are not precise at all.
  1. The reaction: 2Al(s) + 3Br2(ℓ)  2AlBr3(s) , was carried out as reported below:

Al(s) / Br2(ℓ) / AlBr3(s)
Before reaction / 6 moles / 10 moles / 0 mole
After reaction / 0 mole / 1 mole / 6 moles

Which of the following statement(s) describe the reaction?

  1. The reaction did not go to completion.
  2. Al was the limiting reactant.
  3. Br2 was the limiting reactant.
  4. Both statements A and B are correct.
  5. Both statement A and C are correct.
  1. What factors do you think may lead scientists (in industry, for example) to choose one certain starting material as the limiting reactant and another as the excess reactant?

(I)The reactant present in excess must be very reactive.

(II)The reactant present in excess must be relatively inexpensive.

(III)The reactant present in excess must be the one that is easily removed from the product.

(IV)The reactant present in excess must be in solid form.

1

  1. I, II and IV only.
  2. II, III and IV only.
  3. II and III only.
  4. III and IV only.
  5. I, II, III and IV.

1

  1. These are statements about empirical and molecular formulas. Choose the INCORRECT statement:
  1. An empirical formula gives the simplest whole number ratio of the different atoms in a compound.
  2. The molecular formula is a simple multiple of the empirical formula.
  3. For molecules of dihydrogen monoxide, the empirical and molecular formulas are identical.
  4. In some cases, two or more different compounds can share the same empirical formula.
  5. The empirical formula is based on the actual number of atoms of each type in the compound.
  1. A much sought-after high explosive compound has the following composition: C = 20.7%; N = 24.1 %; O = 55.2%. What is its empirical formula?

1

  1. C2NO2
  2. CNO3
  3. C4N2O4
  4. C2N2O6
  5. CNO2

1

  1. Give the two products of the acidbase reaction between carbonic acid and sodium hydroxide.

1

  1. H2O and Na2CO3
  2. NaHCO3 and NaOH
  3. NaCl and H2O
  4. Na2O and H2O
  5. H2O and NaOH.

1

  1. 34.62 mL of 0.1510 M NaOH was needed to neutralize 50.0 mL of an H2SO4 solution. What is the concentration of the original sulfuric acid solution?

1

  1. 0.0229 M
  2. 0.218 M
  3. 0.0523 M
  4. 0.209 M
  5. 0.105 M

1

Figure 1

  1. Figure 1 above shows the set up of an experiment for investigating redox titration. Referring to the titration of oxalate ion with potassium permanganate as shown in the diagram, which of the following statement is CORRECT?
  1. Phenolphtalein should be used as the indicator in the titration.
  2. In the titration, permanganate ion () will be oxidized and oxalate ion () will be reduced.
  3. Electrons will be transferred from ion to ion.
  4. At or near equivalence point the colour of the solution in Erlenmeyer flask will change from colourless to light purple.
  5. The objective of the titration is to determine the concentration of the solution.
  1. One method of determining the concentration of hydrogen peroxide (H2O2) in a solution is through redox titration with iodide ion. The net ionic equation for this reaction is:

H2O2 + 2I + 2H+ I2 + 2H2O

A 50.00 mL sample of a hydrogen peroxide solution is found to react completely with 37.12 mL of a 0.1500 M KI solution. What is the concentration of hydrogen peroxide in the sample?

  1. 5.568  102 M
  2. 0.2227 M
  3. 0.1010 M
  4. 0.4041 M
  5. 0.1114 M
  1. A calorimeter
  1. is equal to the molar molar enthalpy of a reaction.
  2. is a dieting aid.
  3. is an indicator of a spontaneous reaction.
  4. is a device used to measure the transfer of heat energy.
  5. is useful in measuring the amount of heat released by endothermic reactions.
  1. Determine what is wrong with the following diagram of a calorimeter used to determine the specific heat of a copper block.

Figure 2

  1. Thermometer should not be hanging above the liquid.
  2. Retort stand should be on the left-hand side.
  3. The liquid should be water not hydrochloric acid.
  4. The stirring rod should be straight and not curved.
  1. I, II and IV only.
  2. I, III and IV only.
  3. I and III only.
  4. III and IV only.
  5. I, II, III and IV.
  1. Atoms of elements in a group in the Periodic Table have similar chemical properties. This similarity is most closely related to the atoms’
  1. number of principal energy levels.
  2. number of orbitals.
  3. number of valence electrons.
  4. atomic masses.
  5. atomic numbers.
  1. A student made the following observations in the laboratory:

(a) / Sodium metal reacted vigorously with water at room temperature while a strip of magnesium did not seem to react at all.
(b) / A magnesium strip reacted with dilute hydrochloric acid faster than an iron strip.
(c) / A copper rivet suspended in silver nitrate solution was covered with silver-coloured stalactites in several days, and the resulting solution had a blue colour.
(d) / Iron granules dropped into a blue solution were coated with a reddish-coloured substance.

The order of decreasing strength of the metals involved is

1

  1. Na , Mg , Fe , Ag , Cu
  2. Mg , Na , Fe , Cu , Ag
  3. Ag , Cu , Fe , Mg , Na
  4. Na , Fe , Mg , Cu , Ag
  5. Na , Mg , Fe , Cu , Ag

1

  1. When a few drops of 0.1 M NaOH were added to 5.0 mL Pb(NO3)2 in a test tube, a white precipitate appears. The ions responsible in the formation of the white precipitate are
  1. and
  2. and
  3. and
  4. and
  5. and

1

  1. Which statement describes how a salt bridge maintains electrical neutrality in the half cells of an electrochemical cell?
  1. It prevents the migration of electrons.
  2. It permits the migration of ions.
  3. It permits the two solutions to mix completely.
  4. It prevents the reaction from occurring spontaneously.
  5. It prevents the formation of precipitation.
  1. In the shorthand notation for an electrochemical cell, what does this single vertical line,  , represents?

1

  1. The cathode.
  2. The anode.
  3. The salt bridge.
  4. The phase boundary.
  5. The external wire.

1

  1. Which of the following statement about electrolysis is TRUE?

A.Electrolysis is the process in which electrical energy is used to cause a spontaneous chemical reaction to occur.

B.In electrolysis, the cations migrate to the negative electrode (anode) while the anions migrate to the positive electrode (cathode).

C.During electrolysis, when ions receive or give up electrons, the resultant product may be liberated as a gas or deposited as solid on the electrode.

D.The quantitative aspect of electrolysis developed by Faraday states that the amount of materials that forms at the electrode is inversely proportional to the total amount of electric charge that has passed through the cell.

E.After electrolysis, the amount of cations deposited as atoms on the electrode can never be determined.

  1. Examples of electrolysis are:
  1. converting water to hydrogen and oxygen.
  2. converting unburned fuel to carbon dioxide and water.
  3. converting molten sodium chloride to elemental sodium and chlorine gas.
  4. electroplating forks and spoons to produce silver-plated dinnerware.
  1. I, II and IV only.
  2. I, III and IV only.
  3. I and II only.
  4. I and IV only.
  5. I, II, III and IV.

-- END OF QUESTION PAPER --


COLLEGE OF ENGINEERING

SEMESTER II 2007/2008

CHEMISTRY LABORATORY WRITTEN TEST ANSWER SHEET

NAME: ______STUDENT ID.: ______

SECTION : ______INSTRUCTOR : ______

Please use 2B pencil to fill the circle completely.
Example: /
1. / / 11. /
2. / / 12. /
3. / / 13. /
4. / / 14. /
5. / / 15. /
6. / / 16. /
7. / / 17. /
8. / / 18. /
9. / / 19. /
10. / / 20. /

CHEF 111 / CHEB 111: CHEMISTRY LABORATORY WRITTEN TEST – SEM II 07/08

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