Basic Chemistry — Final Exam 1

Name:________________________________

Student number:_______________________

Autumn Semester

Basic Chemistry for Engineering/ Fundamental Inorganic Chemistry

Final Exam

3 February 2014

Time: 60 minutes

Instructions: Answer any 4 questions out of 5 possible questions. You may answer more than 4 questions if you wish. Your marks will be taken from your top 4 questions. Show all relevant working. Write all answers and final working in pen. Give your answers to an appropriate number of significant figures. 9 pages including: 1 top page, 1 data page, 1 periodic table, 5 question pages, 1 page for rough working Hand in all pages at the end of the exam. Permissible materials: Calculator. English or English bilingual Dictionary.

Basic Chemistry — Final Exam 2

Equations and Data

Avagadro number 6.022 x 1023 mol–1

0 ºC = 273 K Total heat released/gained by reaction = ∑ ∆Hf products – ∑∆Hf reactants ∆Hf CO2(g) = –393 kJ mol–1 ∆Hf CH4(g) = –74.9 kJ mol–1

∆Hf H2O(g) = –242 kJ mol–1 Density 37% formaldehyde (HCHO) solution: 1.01 g ml–1

Basic Chemistry — Final Exam 3

Question

Basic Chemistry — Final Exam 4

Question 1 A) i) Circle the metals that are useful for being corrosion resistant.

iron uranium aluminium calcium tin manganese

[1]

ii) Choose two metals from the above list and explain how they resist corrosion.

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[4]

B) Tin (Sn) has two possible crystal structures at normal pressures: the metallic β-form and a

brittle, non-metallic α-form.

i) Which form will be a poor conductor of heat?

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[1]

Consult the phase diagram below. Will tin be a good choice of metal for outside electrical

applications.

ii) in the middle of the Pacific Ocean? Why?

iii) at the South Pole? Why?

ii)______________________________________________________________________________

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[2]

iii)_____________________________________________________________________________

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[2]

Basic Chemistry — Final Exam 5

Question 2

A) An inventor says he has invented a catalyst that makes CO2 react with water vapour to give off

heat and generate CH4 and O2 as waste products.

i) Write a balanced equation for this reaction.

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[1]

ii) Without a catalyst, can CO2 and water vapour be used to generate heat according to this

reaction? Demonstrate your answer with a calculation.

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[2]

iii) Does using a catalyst enable CO2 and water vapour to generate heat? Why?

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[2]

iv) Another inventor has made a catalyst that will turn CO2 and water vapour into CH4 and O2 when

using an electrolytic cell. Give one reason why a catalyst might be necessary for this reaction.

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[1]

B) i) Explain, in terms of collision theory, why raising the temperature of a reaction increases the

rate of reaction.

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[2]

ii) Explain, in terms of collision theory, why using a heterogeneous catalyst can increase the rate of

reaction.

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[2]

Basic Chemistry — Final Exam 6

Question 3

A) A laboratory technician is constructing a voltaic cell. Which of the following components and solutions will she need to use. Illustrate your answer with a labelled diagram of the voltaic cell. strip of zinc metal, strip of copper metal, strip of plastic, wooden toothpick, wire(s), voltmeter, salt bridge, zinc sulfate (Zn2+SO4

2–) solution, copper sulfate (Cu2+SO42–) solution, beaker(s), a tap, glass

beads, lighter, battery, cotton wool

[6] B) Given that copper has a stronger affinity for electrons than zinc, write the full equation, ionic equation and two half equations for this reaction. ________________________________________________________________________________

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[4]

Basic Chemistry — Final Exam 7

Question 4 A) Refer to the line drawing of a molecule below: i) How many carbon atoms does this molecule have? _________________

[1] ii) Which of the following functional groups appear on this molecule? Circle the functional groups on the line drawing and write the name next to the circle. benzene ring, double bond (not as part of other functional groups), alcohol (not as part of other functional groups), amine, nitro, ether, carboxylic acid, ketone, halide

[4] iii) Show on the diagram one place where you would expect to find resonance and one place where you would expect to find strong inductive effects.

[2]

B) i) Draw two constitutional isomers of the following molecule:

[2]

ii) Draw one configurational isomer of the following molecule:

[1]

O

NH2

N

S

O

CH3

CH3

OH

O

OH

Basic Chemistry — Final Exam 8

Question 5 A) i) A student accurately measures the boiling point of tap water and finds it to be 101 ˚C. What is

the most likely explanation for this high boiling point?

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[1]

ii) Fish can have difficulty breathing at elevated temperatures. What is the most likely explanation

for this problem?

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[1]

B) i) An aqueous solution of formaldehyde (HCHO) is labelled as being 37% by weight. What is

the concentration of this solution in molar units (M)? (refer to the data sheet for necessary

information)

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[3]

ii) Given that formaldehyde is a gas, should the solution be stored at low or high temperatures to

maintain its maximum concentration? Why?

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[2]

iii) Could this solution be stored at –1 ˚C and still be ready for immediate use as a liquid? Why?

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[2] iv) If the solution partially froze, what would happen to the concentration of formaldehyde in the

remaining liquid?

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[1]

Basic Chemistry — Final Exam 9

Rough Working