Form 5 Lesson 7 Structure

7/29/2019 Form 5 Lesson 7 Structure

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Students name : ________________Subject : Chemistry ForChapter 1 : Rate of reacti

Paper 2

As catalyst

Manganese (IV) oxi

Rate of reaction is invers

with time

reaction is completed

MEGA TUITION CENTRE

___________________ Teachers Name : Mr5 Class Attend : 5 C

on lesson 7 : 2nd Feb 2013 (

e / Iron (III) oxide

ly proportional with time, as the rate of reac

hew Chin Kuenemistry 6.30 4.30 PM)

ion decreased


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mol of KClO3 = MV / 1000 ; mol of KClO3 = (1.0)(4.0)/1000 = 0.004 mol

From equation 2 mol KClO3 = 1 mol of O2mol of O2 = 0.002 mol

V of O2 = mol x Vm ; V of O2 = 0.002 mol x 24 dm3 / mol

= 0.048 dm3 @ 48 cm3

Rate = (48 cm - 0) / (45 s - 0)

= 1.067 cm3 / s

all hydrochloric acid in the mixture is used up


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Mass of CO2 / g

Time / s

at the first 60

rate = 3.5 - 0.0 / 60 - 0

= 0.583 g / s

By using marble in powder form / increase the temperature / add concentration of HCl

Fe (s) + H2SO4 (aq) FeSO4 (aq) + H2 (g)

mol of Fe = mass / Ar ; mol = 3.0 / 56= 0.0536 mol

mol of H2SO4 = MV / 1000 ; mol = (0.5)(30) / 1000

mol = 0.015 mol (limitant)

since 1 mol of H2SO4 = 1 mol of H2 ; mol of H2 = 0.015 mol

Vgas = mol x Vm @ Vgas = 0.015 x 24

V as = 0.36 dm3 360 cm3

Even though the type of acid used are different, but the mol of H+ is the same for both

H2SO4 and HCl, since H2SO4 is a diproctic acid, while HCl is a monoproctic acid


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Rate of reaction in C is higher than A, since catalyst is add into the mixture, CuSO4 helps

to lower the activation energy by providing alternative routes for reaction to occur

The temperature used in Exp B is higher than A. This will increase the kinetic energy of

particles hence caused the collision between reactants become more rapids

Mg (s) + 2 H+ (aq) Mg2+ (aq) + H2 (g)

Since ethanoic acid is weak acid while HCl is strong acid. the concentration of H + in HCl

is higher, hence caused a higher frequency of effective collision

Since the amount of H+ given by H2SO4 is 2 times greater than amount of H+ given by

HCl. Higher the concentration of H+

, higher the frequency of effective collision

Rate of reaction in S is higher than Q, since catalyst is add into the mixture, CuSO 4 helps

to lower the activation energy by providing alternative routes for reaction to occur

Time taken for the reaction to occur will be lower than 35 second, as temperature increase,

rate of reaction also increase. This is due to, particles has higher kinetic energy which caused

a higher frequency of effective collision.


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5 Carbon dioxide gas is liberated when limestone reacts with dilute acids. Figure below shows the volume ofcarbon dioxide gas collected at room conditions during the duration of the reaction.

(a) Write an equation for the reaction of limestone with dilute hydrochloric acid.

.

(b) (i) How long did the reaction last?

(ii) What is the total volume of carbon dioxide gas evolved? .(iii) Calculate the average speed of the reaction.

(c) Calculate the rate of reaction at t = 60 s and t = 90 s.At 60 s, rate = (80 - 40) / (120 - 30) = 0.444 cm3 / s

At 90 s, rate = (80 - 50) / (165 - 30) = 0.222 cm3 / s

(d) Calculate the mass of limestone reacted.

Using mol of CO2 = V / Vm ; mol = 70 / 24000 cm3

/ mol= 0.00292 mol

From the chemical equation ; 1 mol of CO2 = 1 mol of CaCO3Hence mol of CaCO3 = 0.00292 mol

Mass of CaCO3 = mol x RMM ; mol = 0.00292 mol x [40 + 12 + 3(16)]mass = 0.292 g

(e) The concentration of the hydrochloric acid is 0.25 mol dm-3

. Calculate the volume of hydrochloricacid reacted.

From mol of CO2 reacted = 0.00292 mol ;Since 2 mol HCl = 1 mol CO2 ; mol of HCl = 0.00146 mol

Volume of HCl = mol x 1000 / M ; VHCl = 0.00146 x 1000 / 0.25VHCl = 5.84 cm

3

CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (l)

210 s

70 cm3

Rate = 70 / 210 = 0.33 cm / s


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6 Figure below shows the set-up used to investigate the reaction between calcium carbonate and hydrochloricacid.

The volume of carbon dioxide was recorded at 10-minute intervals under room conditions. Some of thecalcium carbonate remained undissolved at the end of the experiment. The results of the experiment aregiven in the following table.

Time (min) 0 20 40 60 80 100 120Volume of CO2collected (cm

3)

0 700 975 1140 1175 1200 1200

(a) Write an ionic equation for the reaction between calcium carbonate and hydrochloric acid.

.(b) (i) Complete the table below.

Time interval (min) Volume of gas collected (cm )0 - 20 70020 - 40 275

40 - 60 16560 - 80 25

(ii) Explain the variation in the volumes of carbon dioxide collected during these intervals.

Volume of the gas collected decrease with the interval time due to the amount of reactants used for the

reaction become smaller with time. Hence the amount of product obtained will be lower with time

(c) Why did the reaction stop after 100 minutes?

CO32- (s) + 2 H+ (aq) + CO2 (g) + H2O (l)

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Form 5 Lesson 7 Structure