Rates of Reaction

Question 1

Steep stope means?

Answer 1

Fast reaction

Question 2

Mean rate of reaction formula

Answer 2

quantity of product formed / time taken

Question 3

What is collision theory?

Answer 3

chemical reactions can only take place when the reacting particles collide with each other. collisions must have sufficient energy

Question 4

RP 5 Rates of reaction

RP 5 Disappearing cross reaction, effect of conc

Answer 4

1. Measuring cylinder to put 10cm3 of sodium thiosulfate solution to conical flask
2. Place conical flask onto printed black cross
3. Add 10cm3 HCL to conical flask
4. Swirl solution and start stopwatch
5. Look down through top of flask
6. Solution will turn cloudy and wont see the cross
7. Repeat with low conc sodium thiosulfate solution
8. Repeat whole and calc mean values for each conc of sodium thiosulfate solution

Question 5

rp 5 disappearing cross

sodium thiosulfate solution + Hcl

Answer 5

sulfure (solid) - makes solution go cloudy (causes turbidity)

Question 6

What is reproducibility

Answer 6

• Can be repeated by antoher using a diff technique or equipment
• Same result

Question 7

Prob with disappearing cross experiment

Answer 7

• diff ppl have diff eyesights = some ppl can see cross for longer = diff results
• HOWEVER, cross is same size so prob not too great

Question 8

RP 5

How to measure vol of a gas produced by a reaction

Answer 8

1. Use measuring cylinder to place 50cm3 HCl into conical flask
2. Attach conical flask to bung and delivery tube
3. Place delivery tube into container filled with water
4. upturned measuring cyclidner filled with water over delivery tube
5. Add 3cm strip of MG to HCL and start stopwatch
6. Hydrogen gas produced and thats trapped in MC
7. Every 10s, measure vol of H gas until reaction over
8. Repeat with diff conc of HCL

Question 9

rp 5 measure gas

magnesium + hcl

Answer 9

hydrogen + magnesium chloride

Question 10

Greater conc means?

Answer 10

faster reaction

Question 11

larger surface area means?

Answer 11

faster reaction

Question 12

What causes a reaction to become faster?

Answer 12

• larger sa
• higher conc of a chemical
• higher temp
• catalyst

Question 13

What does cotton wool on a conical flask do?

Answer 13

• allows carbon dioxide to escape
• prevents acid from splashing out of flask

Question 14

Activation energy

Answer 14

min aount of energy that particles must have in order to react collide successfully

Question 15

Why does increasing temp increase rate of reaction?

Answer 15

• increase energy of particles
• move faster
• increases freq of collisions
• each collision has more energy
• can overcome avtivation energy needed

Question 16

Catalyst

Answer 16

increase rate of chemical reactions but arent used up during reaction

Question 17

why are catalysts important?

Answer 17

• allows us to carry out reactions quickly without needing to increase temp
• saves money
• resuable

Question 18

how do catalysts work

Answer 18

• provides a diff pathway for reaction that has a lower activation energy

Question 19

What is produced when you heat hydrated copper sulfate (blue)? What type of reaction is it? What type of reaction is the reversible reaction?

Answer 19

• anhydrous copper sulfate (white) + water
• ENDOTHERMIC
• If you add water to anhydrous copper sulfate, reaction reverses, energy released, hot, EXOTHERMIC

Question 20

What is equilibrium?

Answer 20

forward and reverse reactions will take place at the same rate in a sealed container

Question 21

Le Chateliers Princple

Answer 21

If a system is at equilibrium, and a change is made to the conditions, then the system reponds to counteract the change

Question 22

Where does equilibrium only happen in?

Answer 22

in a closed system

Question 23

Where does equilibrium lie when the conc of the products are higher?

Answer 23

To the right

Question 24

exothermic
endothermic
arrows

Answer 24

exo = right
endo = left

Question 25

What happens to the temp of a system during an exothermic reaction?

Answer 25

increases

Question 26

What does the pressure of a gas depend on?

Answer 26

the number of molcules

Question 27

What happens if you increase pressure on a reversible reaction at equilibrium

Answer 27

position of equilibrium shifts to the side with small number of molecules

Question 28

What happens if you decrease pressure on a reversible reaction at equilibrium

Answer 28

position of equilibrium shifts to the side with larger number of molecules

Question 29

What 3 things can cause the equilibrium to change?

Answer 29

Temp, pressure and concentration

Question 30

Chateliers = If you decrease the temperature which reaction would increase?

Answer 30

exothermic (right)

Question 31

Chateliers = If you increase the temperature which reaction would increase?

Answer 31

Endothermic (left)

Question 32

Chataliers: If you increase conc of products, which reaction will increase?

Answer 32

backwards reaction will increase

Question 33

What happens if the conc of a reactant is increased?

Answer 33

more products will be formed until equilibrium is reached again

Question 34

What happens if the conc of a product is decreased?

Answer 34

more reactants will react until equilibrium is reached again

Question 35

What happens if the temp of a system at equilibrium is increased?

Answer 35

• amount of products at equilibrium increases for an endothermic reaction
• products at equilibrium decreases for an exothermic reaction.

Question 36

What happens if the temp of a system at equilibrium is decreased?

Answer 36

• products at equilibrium decreases for an endothermic reaction
• amount of products at equilibrium increases for an exothermic reaction.

Question 37

What is endo and exo in reversible in terms of temp?

Answer 37

• exo = releasing energy so increase temp
• endo = take in energy so decrease