7. Chemical Reaction

Question 0

Describe the effect of particle size on rate of reaction

Answer 0

Lower particle size, higher rate because small particle have more surface area in which particle can collide

Question 1

Describe the effect of concentration on rate of reaction

Answer 1

Higher concentration, higher rate because particles have more chance of colliding

Question 2

Describe the effect of catalyst on rate of reaction

Answer 2

Speed up reaction and remaining chemically unchanged

It lowers the activation energy so reaction can take place with less energy

Question 3

Describe the effect of temperature on rate of reaction

Answer 3

Higher temperature higher rate

Question 4

Describe light sensitive reaction

Answer 4

Light provides energy for the reaction

Higher light intensity, higher rate of reaction

Question 5

Describe the reaction of silver salt

Answer 5

Surface of b&w photo film contains tiny crystals of silver bromide
When light shine on, silver bromide breaks down by silver ions accept electrons from the bromide ions and become silver atom. It is reduced
2ag+ + 2e- -> 2ag

Question 6

Describe photosynthesis

Answer 6

The reaction between carbon dioxide and water in the presence of chlorophyll and sunlight (energy) to produce glucose and oxygen

Question 7

Define reversible reaction

Answer 7

Reactions which can go both ways depending on the condition

Product can react to form the original reactant again

Question 8

Define equilibrium reaction

Answer 8

Both forward and reverse reactions are going on at the same time

Question 9

Features of equilibrium reaction

Answer 9

Reactants or products must not escape from the reaction mixture - closed system
Can be approached from either direction
Can start with only the reactant/product. Whichever we start with. We end up with fixed concentration of reactant and product in the mixture
Rate of forward reaction = reverse
Dynamic equilibrium
Concentration of the reactant and product does not change

Question 10

What is dynamic equilibrium

Answer 10

The reactant are continually being changed to products and products are being changed back to reactants

Question 11

Describe the effect of pressure on the position of equilibrium

Answer 11

Only affect the reactant where there is a gas in the equation
Higher pressure moves the equilibrium to side with smaller number of moles so that the overall number of molecules is reduced.
Lower pressure moves the equilibrium to side with larger number of moles
Equal volume -> no effect

Question 12

Describe the effect of temperature on the position of equilibrium

Answer 12

Higher temperature, it moves in the endothermic direction

Lower temperature, it moves in the exothermic direction

Question 13

Describe the effect of concentration on the position of equilibrium

Answer 13

Decrease reactant/ increase product
-> move it to the reactant side
Increase reactant/ decrease product
Move it to the product side

Question 14

What is oxidation

Answer 14

Gain of oxygen

Loss of electron

Question 15

What is reduction

Answer 15

Loss of oxygen
Gain of electron
Removal of hydrogen from a compound

Question 16

What is redox reaction

Answer 16

Involve both oxidation and reduction at the same time

Question 17

Describe the color changes of potassium manganate (VII) in redox reaction

Answer 17

In acidic solution it is a good oxidant
When it oxidize a substance, it color changes from purple to colorless
It can be use as a test for reductant

Question 18

Describe the color changes of potassium iodine in redox reaction

Answer 18

In acidic solution it is a good reductant
When it reduces a substance, it’s color changes from colorless to brown
It can be use as a test for oxidant