SEMESTER 1 EXAMINATION 2009

THE UNIVERSITY OF THE SOUTH PACIFIC

CHF02 FOUNDATION CHEMISTRY A

Time Allowed: 3 hours plus 10 minutes reading time Total Marks: 100

INSTRUCTIONS TO CANDIDATES 1. There are three sections in this paper. All sections are compulsory. 2. Answer ALL questions in blue or black ink. 3. Section A is worth 20 marks, Section B is worth 30 marks, and Section C is

worth 50 marks. 4. Section A consists of 20 multiple-choice questions. Circle the letter that

represents the best answer to each question on the answer grid provided. 5. Sections B and C consists of numerical type questions requiring calculations.

Write your answers in the spaces provided on the question paper. If you need additional space, use the facing page.

6. Show all working clearly. Marks will be allocated on the basis of logical

working. 7. Calculators are permitted, provided they are not programmed before the start of

the examination. 8. Periodic Table and Fundamental Constants are provided at the end of this paper. 9. You are required to fill in your details below. STUDENT NAME: _________________________________________

STUDENT ID. NO: ________________________________________

CAMPUS: ________________________________________

Section A Multiple Choice (20 marks) There are 20 multiple-choice questions. Circle the letter that represents the best answer in the answer grid provided. Each question is worth 1 mark.

1. The leaves of some trees turn from green to brown because the chlorophyll chemically breaks down and the green color disappear. This statement is an example of a

A. reproducible observation. B. hypothesis. C. theory. D. scientific law. 2. The density of lead is 11.35 g/cm3. The experimental values obtained for the

density of lead are 10.9, 11.5 and 11.8 g/cm3. Which one of the following best describes this collection of data?

A. Accurate B. Precise C. Precise and accurate D. Neither precise nor accurate 3. How many chloride ions are required to neutralize one aluminum ion? A. 3 B. 2 C. 1 D. 4 4. Which one of the following is an extensive property? A. Volume B. Density C. Temperature D. Color 5. You have already determined that there are 3.36 x 10-6 moles in 2.92 x 10-4 g of

strontium. How many atoms of strontium are in this sample? A. 2.02 x 1018 atoms B. 1.76 x 1020 atoms C. 5.68 x 10-21 atoms D. 4.98 x 10-19 atoms

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6. Denim jeans appear to be blue in color because A. the molecules in the denim fabric absorb blue light. B. the molecules in the denim fabric emit all colors except for blue. C. the molecules in the denim fabric emit red and green light, absorbing the blue. D. the molecules in the denim fabric absorb all visible light and reflect blue light. 7. Wave mechanics, which suspended Bohr’s model, take into account A. the proton-electron repulsions. B. the probability that electron exist. C. the dual nature (particle/wave) of the electron. D. the existence of more than four principle energy levels. 8. Which one of the following completely depicts the relative energies of the four

types of subshells? A. p < d < s < f B. f < d < p < s C. s < p < d < f D. d < s < f < p 9. The general valence electron configuration for noble gas atoms is

A. ns2np6B. ns2np5C. ns2np4D. ns2np3 10. What is the maximum number of shared electrons that oxygen can possess? A. 1 B. 2 C. 4 D. 8 11. Which one of the following represents the bond with the greatest polarity? A. O – F B. H – O C. C – S D. N – Cl

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12. Which one of the following compounds possesses dipole-dipole interaction? A. I2B. SO2 C. CO2D. BCl3 13. The polarizability of a molecule is A. inversely proportional to its mass. B. proportional to the number of electrons. C. proportional to temperature. D. proportional to the dipole-dipole forces 14. The meniscus formed by H2O in a graduated cylinder is concave, whereas the

meniscus formed by mercury in a barometer in convex. Which one of the following statements best explains this phenomenon?

A. Mercury is more viscous than water B. Water possesses hydrogen bonding and mercury does not. C. Water has a higher freezing point. D. Mercury has a larger surface tension. 15. According to Rutherford, the atom consists of which of the two parts? A. Nucleus and the extra-nuclear part B. Neutrons and electrons C. Electrons and protons D. Protons and neutrons 16. An example of a covalent network solid is A. diamond B. potassium C. iodine D. sodium chloride

17. Complete this sentence: The PCl5 molecule has

A. nonpolar bonds, and is a nonpolar molecule. B. nonpolar bonds, but is a polar molecule. C. polar bonds, and is a polar molecule. D. polar bonds, but is a nonpolar molecule.

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18. What is the maximum number of electrons in an atom that can have the following set of quantum numbers?

n = 4 l = 3 ml = -2 ms = + ½

A. 0 B. 1 C. 2 D. 6 19. Which of these pairs consists of “isoelectronic” species? A. Mn2+ and Ar B. Zn2+ and Cu2+ C. Na+ and K+D. K+ and Cl-

20. Each of the following substances is a liquid at -50 °C. Place these liquids in order of

increasing vapor pressure.

dimethyl ether (CH3OCH3), propane (C3H8), ethanol (CH3CH2OH)

A. ethanol < dimethyl ether < propane B. propane < dimethyl ether < ethanol C. dimethyl ether < ethanol < propane D. propane < ethanol < dimethyl ether

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ANSWER SHEET SECTION A: Multiple Choice (20 marks) Circle the letter in the answer grid that represents the best answer to each question.

1 A B C D

2 A B C D

3 A B C D

4 A B C D

5 A B C D

6 A B C D

7 A B C D

8 A B C D

9 A B C D

10 A B C D

11 A B C D

12 A B C D

13 A B C D

14 A B C D

15 A B C D

16 A B C D

17 A B C D

18 A B C D

19 A B C D

20 A B C D

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Section B Short Answer Questions (30 marks) There are 10 questions. Each question is worth 3 marks. 1) (a) Perform the following calculations and round off the answer to the correct number

of significant figures. (1½ marks)

(13.7 + 0.027)8.221

(b) Convert 2 km/min to m/s. (1½ marks) 2)a) Classify the following statements as either true or false. (3 marks) (i) Chemical compounds are composed of atoms of different elements combined in

specific ratio like HO1/2 (ii) Atoms of the same elements can possess a different number of protons .

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(iii) Performing dimensional analysis enables one to convert one set of units to another.

(iv) A homogeneous mixture possesses distinguishable phases. (v) When a dark piece of clothing is accidentally bleached, it has undergone a

chemical change. (vi) A liter of air weighs the same as a liter of lead metal. (vii) In all aqueous solutions water is used as a solvent. 3) How many atoms are present in 17.0 mol of water (H2O)? (3 marks) 4) (i) What are emission spectra? (1 mark) (ii) How do line spectra differ from continuous spectra? (1 mark)

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(iii) Explain the significance of atomic spectra. (1 mark) 5) Which has a higher percentage of oxygen; Morphine (C17H19NO3) or heroin

(C21H23NO5)? (3 marks)

6) 250 cm3 gas is collected by displacement of water at 20 0C and at 98.0 kPa

pressure. Calculate the volume of dry gas at STP. [Note: saturated vapor pressure of water = 2.4 kPa]. (3 marks)

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7) (a) Discuss the similarities and differences between a 2s and a 3s orbital. (2 marks)

(b) Write down the electron configuration of Cu using the s.p.d.f notation.

(1 mark) 8) Classify each of the following atomic electron configurations as either “a ground

state”, “an excited state” or “a forbidden state”. (1 mark) (i) 1s22s02p3 (ii) 1s22s22p63s23p62d1 (b) Determine if O2- ion is diamagnetic or paramagnetic. (2 marks)

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9) Draw the resonance structure of CO ion. (3 marks) −23 10) Name and explain the type of intermolecular forces that exists between molecules

of (i) CH3Cl (ii) HF (iii) CO2

(3 marks)

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Section C Long Answer Questions (50 marks) There are 5 questions. Each question is worth 10 marks. 1) (a) The depletion of ozone (O3) in the stratosphere has been a matter of great concern

among scientists in recent years. It is believed that ozone can react with nitric acid (NO) that is discharged from the high altitude jet planes. The reaction is

O3 + NO O2 + NO2

Assume that in such a reaction, 0.740 g of O3 reacts with 0.670 g of NO. (i) Calculate which reactant is the limiting reactant. (3 marks)

(ii) Calculate how many grams of NO2 will be produced? (2 marks)

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(iii) Calculate the mass in grams of excess reagent remaining at the end of the reaction? (2 marks)

(b) 0.04 mol of sodium chloride reacts with silver nitrate as shown by the following

reaction.

NaCl + AgNO3 AgCl + NaNO3 (i) Calculate the theoretical yield of AgCl. (1½ marks) (ii) Calculate the % yield if 5g of AgCl was obtained from this reaction.

(1½ marks)

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2) (a) A certain supply of hydrochloric acid has a concentration of 36.0 % by mass HCl. The density of the solution is 1.19 g/cm3. [Note: Mr (HCl) = 36.5 g/mol].

(i) Calculate the molarity of HCl. (4 marks) (ii) Calculate the molality of HCl. (3 marks)

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(b) Calculate the mass of NaCl in 46.6 g of 3.00 % by mass saline solution. (3 marks)

3) a) Chlorine has 2 naturally occurring isotopes, 35Cl (isotopic mass 34.9689 amu) and 37Cl (isotopic mass 36.9659 amu). If chlorine has an atomic mass of 35.4527 amu, what is the percent abundance of each isotope? (5 marks)

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(b) Sodium vapor lamps are often used in residential street lighting. They give off a yellow light having a frequency of 5.09 x 1014Hz. What is the wavelength of this light in nm? (3 marks)

(c) Wavelength of a red light is about 600 nm and the wavelength of blue light is

about 500 nm. Which of the two has (i) a higher frequency? (ii) a higher energy? (2 marks) 4) a) The 1st three ionization energies for calcium are 590, 1145 and 4912 kJ/mol,

representing the formation of Ca+, Ca2+ and the Ca3+ ions. Explain why there is such a large change in the required energy to remove the 3rd electron from the calcium?

(2 marks)

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b) List the following ions in order of increasing ionic radius. (2 marks) N3-, Na+, Mg2+ c) Determine the following for the third shell of an atom. (i) The number of subshells (½ marks) (ii) The designation of each subshell. (1½ marks) (iii) The total number of orbitals. (1½ marks) (iv) The maximum number of electrons that can be contained in the shell. (1 mark)

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c) The quantum number 2, 1, 0, +½ is for an element in the periodic table with 16 electrons. (1½ mark)

(i) What is the principle energy level? (ii) What type of orbital is designated? (iii) What is the approximate position of this in the periodic table? 5) a) Clearly use the VSEPR theory to work out the basic geometry and the final shape

of ammonia, NH3 (3 marks)

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b) (i) How does the degree of hydration of alkali metal ion differ with ionic size? (1 mark) (ii) Explain the mobility of Li+ ion and Cs+ ion in water. (1 mark) (c) State 2 advantage of using Down’s cell in the extraction of sodium by the

electrolysis process. (1 mark) d) The following questions (i – iii) refer to the electrolysis of lithium chloride. (i) Name the anode and cathode in this process. (1 mark) (ii) Write electron-half reactions that occur at cathode and anode. (2 marks) (iii) Why is KCl added during electrolysis of lithium chloride? (1 mark)

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mol.KL.Torr

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INSTRUCTIONS TO CANDIDATES STUDENT NAME: _________________________________________ STUDENT ID. NO: ________________________________________ SECTION A: Multiple Choice (20 marks)