Chemistry 534 Chemistry 534 Chemistry 534 Chemistry 534 Chemistry 534

551534 - Chemistry

Guide

1- Contents

Question / Item / Objective / Type / Skill
1 / 0066 / M04.02.04 / Choix multiple / Mastery of Applications
2 / 0067 / M04.02.02 / Réponse courte / Mastery of Applications
3 / 0068 / M04.01.02 / Réponse courte / Mastery of Applications
4 / 0103 / M04.03.03 / Choix multiple / Mastery of Concepts
5 / 0105 / M04.01.02 / Choix multiple / Mastery of Problem Solving
6 / 0114 / M04.02.02 / Réponse courte / Mastery of Applications
7 / 0129 / M04.01.02 / Choix multiple / Mastery of Applications
8 / 0130 / M04.02.02 / Choix multiple / Mastery of Applications
9 / 0133 / M04.02.02 / Choix multiple / Mastery of Concepts
10 / 0065 / M04.02.04 / Choix multiple / Mastery of Applications

2- Correction key

1 and 4 only

0.083 mol/s

Note : Accept 0.08 mol/s

The situation in which the beaker on the right produces the more rapid reaction is : the fourth.

Name: ______

REVIEW QUESTIONS #2: REACTION RATES:Date: ______

Given the system A + B  C + D
The energy distribution graph for a given reaction is shown on the right. /

Which energy distribution graph below shows the effect of an increase in temperature on the rate of this reaction?

Chemistry 534 Chemistry 534 Chemistry 534 Chemistry 534 Chemistry 534

The wine (CH3CH2OH = alcohol) inside a bottle oxidizes in contact with air (O2) to be transformed into vinegar (CH3COOH). The equation can be represented by :



Which of the following changes would increase the rate of the oxidation of wine?

1.Increase the surface area in contact with air (O2).

2.Decrease the air pressure.

3.Place the bottle in the refrigerator.

4.Add the catalyst MnO2 to the wine.

A given reaction can be symbolized by the following equation:

A(g) + B(g)  C(g)

The graph below shows the number of moles of substance C formed by the reaction, as a function of time.

What is the average rate for the formation of substance C during the first three seconds?

Read the following text.

CANADIANS NEVER INVENT ANYTHING
FALSE!
It is imperative that we clean our air. Professor Philip Pacey, of DalhousieUniversity, Halifax, has invented something that should help to do this. He has produced a ceramic oxygen detector, about the size of a thimble, made of calcium oxide and zirconium oxide. This device can be installed in the exhaust system of an automobile.
His detector measures the quantity of oxygen present in the exhaust gases to determine whether the combustion has been efficient. This information permits adjustment of the air-gasoline mixture. The gasoline consumption is improved and the emission of the pollutants, oxides of carbon and nitrogen, is reduced.
Such detectors are not new, but that of Professor Pacey reacts more rapidly than most of the others and is compatible with automobile engines.
Pleins feux sur la chimie, October 1992, Alberta

This technological improvement is the result of research conducted by environmentally-conscious scientists. Which of the following topics is the focus of this research?

A) / The dangerous effects of automobile engines
B) / The energy produced by combustion in these engines
C) / The reversible chemical energy in the air-gasoline mixture
D) / The efficiency of the combustion in these engines

Eric wants to measure the rate of combustion of a candle. His results are recorded in the table below.

Before combustion / After combustion
Mass of candle (g) / 165.5 / 162.0
Time (h:min:s) / 13:42:00 / 13:47:00

The equation is : C25H52(s) + 38 O2(g) 25 CO2(g) + 26 H2O(g)

Four students calculate the rate of this combustion reaction using Eric's results.

Student / Result
Pauline / 2.0  103 mol/min of C25H52 consumed
Peter / 1.0  103 mol/min of C25H52 consumed
Jacqueline / 3.5 g/min of C25H52 consumed
Andie / 7.0  101g/min of C25H52 consumed

Which students have correctly calculated the rate of this combustion reaction?

A) / Peter and Jacqueline / C) / Pauline and Andie
B) / Peter and Andie / D) / Pauline and Jacqueline

To compare the rates of reaction, you put 100g of calcium carbonate, CaCO3(s), into eight solutions of hydrochloric acid HCl(aq). You group them in pairs as shown in the four situations below :

In which situation (1, 2, 3 or 4) will the beaker on the right react more rapidly than the beaker on the left?

An ecologist, experimenting with atmospheric equilibrium, wishes to promote the reproduction of highly photosynthetic algae.

He uses the following equation for photosynthesis :

6 H2O + 6 CO2 + energy from sunlight  C6H12O6 + 6 O2

After having selected 5 appropriate species of algae, he decides to measure their rate of photosynthesis.

Which of the following procedures can be used to make the appropriate calculations for equal quantities of each species of algae?

1.Measure the mass of CO2 used up per unit of time.

2.Measure the variation in pH value in the water per unit of time.

3.Measure the solubility of CO2 and the solubility of oxygen in water.

4.Measure the volume of oxygen produced per unit of time.

5.Measure the quantity of energy contained in one mole of C6H12O6.

A) / 1 and 2
B) / 1 and 4
C) / 2 and 4
D) / 3 and 5

Curves 1 and 2 on the graph below represent energy pathways for the same chemical reaction. The reaction rate is faster for pathway number 2.

Chemical Reaction

Which factor is most probably responsible for the pathway in curve 2?

A) / Increase in temperature
B) / Increase in contacting surface area
C) / Decrease is concentration of reactants
D) / Presence of a catalyst

During an experiment dealing with the factors that influence the rate of rust formation (slow oxidation), a team of students obtain the following results :

RESULTS
N° / DESCRIPTION / RESULT
Control
Nail exposed to air and humidity / Moderate rusting
1 / Nail exposed to dry air only / No rust
2 / Nail exposed to air, humidity and salt / Rapid rusting and extensive rusting
3 / Nail partially wrapped in aluminum foil, exposed to air and humidity / Less rust than in control test tube
4 / Nail covered in grease, exposed to air and humidity / No rust

Which experimental result above best justifies the technological applications below?

a.A manufacturer of electronic equipment inserts a porous bag into his packaging. This bag contains a dessicator. (A drying agent.)

b.A chemist suggests the addition of anti-oxidant wrapping to certain food products before they are put on shelves for sale.

c.Every spring, your father paints the swing.

A) / a-1, b-3 and c-4
B) / a-2, b-1 and c-3
C) / a-2, b-3 and c-4
D) / a-4, b-2 and c-1

The automobile engine (internal combustion engine) is powered by gasoline and air.



Among the factors proposed below, which does NOT modify the rate of combustion of gasoline?

A) / Vary the quantity of O2 present in the air.
B) / Vary the nature of gasoline used.
C) / Vary the pressure of O2.
D) / Vary the quantity of CO2 in the exhaust gases.