rateofreaction-120105221844-phpapp01 (1)

Volume of

gas/ cm3

Time/ s

( 45 – 20 )

50

Rate of reaction =

Changes in amount of reactant/product

Time taken Increase in amount of product Decrease in amount of reactant

Concentration of

HCl / moldm-3

Mass of

ZnCO3 / g

Time/s Time/s

Volume of gas

CO2/cm3

Mass of

ZnCl2 / g

Time/s Time/s

ZnCO3(s) + 2HCl(aq) ZnCl2(aq) + CO2(g) + H2O(l)

MEASURING RATE OF REACTION

Average rate of reaction =

Change in selected quantity

Time taken

Instantaneous Rate Of

Reaction

= the gradient of the graph

at any given time.

The average rate of reaction =

for the whole reaction

= 0.444 cm3 s-1

40

90

Average rate of reaction in first

50 seconds

= Volume at 50 seconds

Time taken

= 30/50

=0.6 cm3 s-1

The average rate of reaction

between 50 and 90 seconds

= V at 50 s – V at 90 s

Time taken

= (40-30)/(90-50)

= 0.25 cm3 s-1

The rate of reaction at 50 second

= the gradient of tangent to the curve at the given

time

= ∆ y cm3

∆ x s

= 45 - 20

90 - 25

= 0.0345 cm3 s-1

- Plot a graph

- Draw a tangent

- Find the gradient

solution

Suitable measurable

changes:

� Colour

� Concentration

� Temperature

� Volume of gas

� Mass

� Precipitation

� Pressure

45

20

25 90

Volume of

gas/ cm3

Time/ s

( 45 – 20 )

50

( 90 – 25 )

40

30

25 90

18

High Rat e of reaction

-Fast reaction, short time

Low Rate of reaction

-Slower reaction, long time

Experiment I

(small chip)

Experiment II

(large chip)

CONCENTRATION

When concentration

of reactant increase

rate of reaction

increase

Gradient at t1 steeper > Gradient at t2

Rate of reaction t1 >Rate of reaction t2

Gradient in reaction I steeper > Gradient

in reaction II

Rate of reaction I >Rate of reaction II

Factors affecting rate of reaction

SIZE

When total surface

area larger, rate of

reaction increase

TEMPERATURE

When temperature

increases, rate of

reaction increase

PRESSURE

When pressure

increase rate of

reaction

increase

CATALYST

When positive

catalyst are used.

rate of reaction

Aim : To investigate the effect of the size of reactant

on the rate of reaction

Problem statement : How does the size of calcium

carbonate chips affect the rate of its reaction with

dilute hydrochloric acid?

Hypothesis : The rate of reaction between calsium

carbonate and hydrochloric acid is increases when

smaller size calcium carbonate used

Manipulated variable : The size of calcium carbonate

Responding variable : The rate of reaction

Fixed variables : Volume and concentration of HCl

Observable Change: Volume of gas CO2 in every 30 s

Time/s

• The rate of reaction in experiment II is higher than

experiment I because the gradient of the graph II is

greater than graph I throughout the reaction.

•••• The rate of reaction of the small calcium carbonate

chips is higher compared than large calcium

carbonate chip

• The maximum volume of carbon dioxide gas

collected for both experiments are equal because

the no. of mole of hydrochloric acid are the same

EFFECT OF THE SIZE OF REACTANT ON

RATE OF REACTION

Experiment I: 20 cm3 of 0.5 mol dm-3

hydrochloric acid + excess of CaCO3 SMALL

CHIPS

Experiment II: 20 cm3 of 0.5 mol dm-3

hydrochloric acid + excess of CaCO3 LARGE

CHIPS

Equation:

2CaCO3 + 2HCl CaCl2 + H2O + CO2

The number of mole of HCl in both experiments:

= MV/1000

= 22 x 0.5)/1000

=0.01 mol

CO2 gas

calcium

carbonate

hydrochloric acid

Water

CO2

Gas

Reaction has stopped

Volume of

carbon dioxide/ cm3

Observable Change: Yellow precipitate formed.

Aim : To investigate the effect concentration of sodium

thiosulphate on the rate of reaction

Problem statement : How does concentration of

sodium thiosulphate affect on the rate of reaction

Hypothesis : When concentration of sodium

thiosulphate increase, rate of reaction will increase.

Manipulated variable : concentration of sodium

thiosulphate


Fixed variables : Volume and concentration of HCl

� Concentration is inversely

proportional to time.

� When the concentration of

Na2S2O3 increases, a shorter

time is needed for marked

across to disappear.

� Concentration is directly

proportional to 1/time.

� [ 1/time shows the rate of

reaction ]

� When the concentration of

Na2S2O3 increases, the rate of

reaction is increase

Ionic Equation:

S2O3 2- + 2H+ S + SO2 + H2O

- The rate of reaction in exp I is

higher than exp II

- Exp I has higher concentration

than Exp II

- Gradient I is steeper than

graph II

- The maximum volume of

carbon dioxide gas collected

for both experiments are

equal

- no. of mole of hydrochloric

acid are the same

-

Exp I (high concentration)

Exp II (Low concentration)

Experiment 1 2 3 4 5

Volume of 0.2

moldm-3 Na2S2O3 ,

V1 cm3

50 40 30 20 10

Volume of distilled

water added/cm3 0.0 10 20 30 40

Volume of 1.0 mol

HCl acid added/cm3 5.0 5.0 5.0 5.0 5.0

Concentration of

Na2S2O3/moldm-3 0.2 0.16 0.12 0.08 0.04

Time taken/s 20 23 32 46 95

1/time , s-1 0.05 0.043 0.031 0.022 0.011

CONCENTRATION

‘X’

mark

Sodium thiosulphate

solution

+ Hydrochloric acid

Eye Experiment I: 50 cm3 of 0.2 mol dm-3 sodium

thiosulphate solution + 5 cm3 of 0.5 mol dm-3

hydrochloric acid

Experiment is repeated four times using 0.2 mol dm-3

sodium thiosulphate solution diluted with different

volume of distilled water

Equation:

Na2S2O3 + 2HCl 2NaCl + S + SO2 + H2O

Time /s

Concentration of

Na2S2O3 (mol dm-3) Experiment 1:

2.0 g Magnesium + 50 cm3 of

2.0 mol dm-3 hydrochloric

acid

Experiment II



acid

1/time (s-1)

Concentration of

Na2S2O3 (mol dm-3)

Time /s

Concentration of

Na2S2O3 (mol dm-3)

Volume of carbon dioxide/ cm3

Ionic Equation:

S2O3 2- + 2H+ S + SO2 + H2O

When the concentration

increase, Shorter time

is needed for mark ‘X’

disappear.

When temperature

increase, Shorter time

is needed for mark ‘X’

disappear.

Exp I

(high concentration)

Exp II

(low concentration)

Experiment 1 2 3 4

Temperature/oC 30 40 50 60

Volume of 0.2

moldm-3 Na2S2O3 , 50 40 30 20

Volume of distilled

water added/cm3 0.0 10 20 30

Volume of 1.0 mol

HCl acid added/cm3 5.0 5.0 5.0 5.0

Concentration of

Na2S2O3/moldm-3 0.2 0.16 0.12 0.08

Time taken/s 20 23 32 46

1/time , s-1 0.05 0.043 0.031 0.022

Equation:

Na2S2O3 + 2HCl 2NaCl + S + SO2 + H2O

CONCENTRATION TEMPERATURE

‘X’

mark

Sodium thiosulphate

solution

+ Hydrochloric acid

Eye

Observable changes:

Time required for mark

‘X’ disappear from view.

Concentration of

Na2S2O3 (mol dm-3)

Time /s

Concentration of Na2S2O3 (mol dm-3)

1/time (s-1)

concentration of Na2S2O3 increase

the rate of reaction increase

Time /s

Temperature

Na2S2O3 (mol dm-3)

Shows the rate of reaction

Temperature

Na2S2O3 (mol dm-3)

1/time (s-1)

Experiment 1:



acid at 25 oC

Experiment II



acid at 60 oC

Experiment is repeated four times using 0.2

mol dm-3 sodium thiosulphate solution diluted

with different volume of distilled water

‘X’

mark

Sodium thiosulphate

solution + Hydrochloric acid

Eye

Paper

sheet Paper

sheet

Experiment 1:

2.0 g Magnesium + 50 cm3 of 1.0 mol dm-3

hydrochloric acid

Experiment II

2.0 g Magnesium + 50 cm3 of 1.0 mol dm-3

sulphuric acid

Temperature of Na2S2O3 increase

the rate of reaction increase

Volume of H2

/ cm3

Time /s

Volume of H2

/ cm3

Time /s

Exp II (60 oC)

Exp I

(25 oC)

lower gradient

:. Lower rate

Steeper gradient

:. Higher rate

Decomposition

H2O2 2 H2O + O2

Exp I

(without

catalyst)

Lower gradient

:. Lower rate

Steeper gradient

:. Higher rate

PRESENCE OF CATALYST AMOUNT OF CATALYST

Observable changes:

The presence of oxygen

gas, tested with glowing

wooden splinter

� Manganese(IV) oxide act as catalyst

to increase rate of reaction

� Total volume for both exp I and II same

� Because the molarity and volume of

hydrogen peroxide in both reaction are

same

Experiment 1:

Decomposition of 50

cm3 of 1.0 mol dm-3

Hydrogen Peroxide

Experiment II

Decomposition of 50

cm3 of 1.0 mol dm-3

Hydrogen Peroxide +

1.0 g manganese (IV)

oxide

Problem statement : How does the presence of

catalyst affect the rate of composition of

hydrogen peroxide solution?

Hypothesis : Presence of catalyst increase the

rate of decomposition of hydrogen peroxide

Manipulated variable : Presence of catalyst


Fixed variables : temperature, volume and

concentration of hydrogen peroxide

Problem statement : How does the amount

of catalyst affect the rate of composition of

hydrogen peroxide solution?

Hypothesis : When amount of catalyst used

increase, the rate of decomposition of

hydrogen peroxide increase

Manipulated variable : Mass of catalyst


Fixed variables : temperature, volume and

concentration of hydrogen peroxide

Observable changes:

Volume of gas carbon

dioxide in every 30 s is

recorded

Experiment 1:

Decomposition of 50

cm3 of 1.0 mol dm-3

Hydrogen Peroxide +


oxide

Experiment II

Decomposition of 50

cm3 of 1.0 mol dm-3

Hydrogen Peroxide +


oxide

� When amount Manganese(IV)

oxide increase , rate of reaction

increase

� Total volume for both exp I and II

same

� Because the molarity and volume

of hydrogen peroxide in both

reaction are same

� Quantity of catalyst does not affect

the total volume of produced

Exp II

(1.0 g MnO2)

Exp I

(0.5 g MnO2)

Lower gradient

:. Lower rate

Steeper gradient

:. Higher rate

Properties of catalyst

� Need a small amount

� Specific in action

� Chemically unchanged

� Does not affect amount

product

� Increase rate of reaction

Volume of O2

/ cm3

Time /s

Volume of O2

/ cm3

Time /s

Exp II (with catalyst)

The collisions that lead to a chemical reaction are known as

effective collisions

.

Molecule ust collide

Right

orientation of collision

Achieved a minimun amoun of

energy (Ea)

The frequency of collision between particles

The smaller the size

of reactant, the

larger is the total

surface area

exposed to collision

The higher the

concentration of

reactants, the

higher is the

number of particles

in a unit volume.

The higher the

temperature,

higher is the

energy of reacting

particles.

reacting particles

move faster.

The frequency of effective collision between particles increases

The rate of reaction increases.

Explanation using Collision Theory

Cooking in a pressure cooker

� The high pressure in pressure cooker increases the boiling

point of water to a temperature above 100 °C.

� The kinetic energy of the particles in the food is higher

� Time taken for the food to be cooked is decrease

� Thus the food cooked faster at a higher temperature in a

pressure cooker.

SIZE

CONCENTRATION

TEMPERATUR

The collisions that lead to a chemical reaction are known as

Ea

”

Ea Achieved a

amoun of energy (Ea)

The Collision Theory

collision between particles increases.

The higher the

temperature, the

higher is the kinetic

energy of reacting

particles. The

reacting particles

move faster.

Catalyst provides

an alternative path

of reaction which

needs lower

activation energy

(Ea’)

collision between particles increases

increases.

Cooking of solid food in smaller size

� The total surface area on a smaller cut pieces of food is larger

� The food can absorbed more heat.

� The time taken for the food to be cooked is

Energy Profile Diagram And Activation Energy, E

Ea – The minimum energy the reactant

Ea’ – The lower activation energy in the presence

of a catalyst.

Energy

Explanation using Collision Theory

Storage of food in a refrigerator

� When the food kept in refrigerator, the food lasts longer

� The low temperature in the refrigerator slows down

activity of the bacteria.

� The bacteria produce less toxin ,

� the rate of decomposition of food becomes lower

in pressure cooker increases the boiling

higher.

in a

Reactant

reactants

products

Progress of reaction

Exothermic

reaction

CATALYST TEMPERATURE

Uses of

Catalyst in

Industrial

size

surface area on a smaller cut pieces of food is larger

heat.

me taken for the food to be cooked is shorter

Energy Profile Diagram And Activation Energy, Ea’:

The minimum energy the reactant

The lower activation energy in the presence

of a catalyst.

Progress of reaction

Endothermic

reaction

t in refrigerator, the food lasts longer

slows down the

lower

Energy

Product

Ea

Ea’

Reactant

Haber Process (NH3)

Iron, Fe

Ostwald process (HNO3)

Platinum, Pt

Contact process (H2SO4)

Vanadium (V) oxide,

V2O5

FACTOR EXPLANATION DIAGRAM

Size

Exp I:

2 g of Zinc chip + 50 cm3 1.0

mol dm-3 HCl

Exp II :

2 g of Zinc powder + 50 cm3 1.0

mol dm-3 HCl

Size of zinc in exp. II is smaller than exp I.

Total surface area exposed to collision in exp.

II is larger than exp. I

The frequency of collision between zinc and

hydrogen ion in exp II is higher

Frequency of effective collision between zinc

and hydrogen ion in exp II is higher

Rate of reaction in exp. II is higher

Concentration

Exp I: 2 g of Zinc powder + 50

cm3 0.5 mol dm-3 HCl

Exp II : 2 g of Zinc powder + 50


Concentration of hydrochloric acid in exp. II is

higher than exp I

The number particles per unit volume in exp.

II is higher than exp. I






Concentration

Exp I: 2 g of Zinc powder + 50

cm3 1.0 mol dm-3 CH3COOH

Exp II : 2 g of Zinc powder + 50


Exp III : 2 g of Zinc powder + 50

cm3 1.0 mol dm-3 H2SO4

Experiment I and II

Exp I use ethanoic acid (weak acid) and exp II use

hydrochloric acid (strong acid)

The number of hydrogen ions per unit volume

in exp. II is higher than exp. I






Experiment II and III

Exp III use sulphuric acid (diprotic acid) and exp

II use hydrochloric acid (monoprotic acid)

The number of hydrogen ions per unit volume

in exp. III is higher than exp. II






Volume of

H2/ cm3

Exp I

Exp II

Time/s

Volume of H2

/ cm3

Time /s

Exp II

Exp II

Volume of H2

/ cm3

Time /s

Exp III

Exp I

Exp II

Temperature

Exp I:

2 g of Zinc chip + 50 cm3 1.0

mol dm-3 HCl at 25 oC

Exp II :


mol dm-3 HCl at 40 oC

Temperature of exp. II is higher than exp I.

The kinetic energy of reactant in exp II is higher

than I

The frequency of collision

hydrogen ion in exp

Frequency of effective collision

and hydrogen ion in exp


Catalyst

Exp I:


mol dm-3 HCl

Exp II :


mol dm-3 HCl and 2cm3 of

copper (II) sulphate

Exp II use copper (II) sulphate act as catalyst

Catalyst provides an alternative path of reaction

which needs lo

The frequency of collision

hydrogen ion in exp

Frequency of effective collision

and hydrogen ion in exp


(with catalyst)

Temperature of exp. II is higher than exp I.

The kinetic energy of reactant in exp II is higher

frequency of collision between zinc and





Exp II use copper (II) sulphate act as catalyst

Catalyst provides an alternative path of reaction

which needs lower activation energy (Ea’)

frequency of collision between zinc and





Volume ofcarbon dioxide/ cm

Exp II

Volume of

/ cm3

Exp II (with catalyst)

Volume of carbon dioxide/ cm3

Exp I

Exp II

Time/s

Volume of H2

Time /s

Exp I

HAK MILIK SLM 2011

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