Rate of reaction

Question 1

What is rate of reaction

Answer 1

a measure of how quickly a reactant is used up, or a product is formed

Question 2

what are the two calculations used to measure rate of reaction

Answer 2

quantity of reactant used / time taken

quantity of product formed / time taken

Question 3

what does the rat of chemical reaction tell you

Answer 3

how fast reactants turn into products

Question 4

why are reactions initially fast

Answer 4

because we have a large number of reactant molecules, meaning theres a larger number of collisions per second

Question 5

what is a successful collision

Answer 5

A collision that produces a reaction

Question 6

what is activation energy

Answer 6

the minimum amount of energy needed for a collision to be successful

Question 7

what does collision theory state

Answer 7

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

Question 8

what is the rate of a chemical reaction determined by

Answer 8

the frequency of successful collisions

Question 9

what effect does concentration have on rate of reaction

Answer 9

increasing concentration increases the rate of reaction,

Question 10

why does increasing concentration increase rate of reaction

Answer 10

• because the reactant particles become more crowded as there are more reactant particles in a given volume
• the frequency of collisions between reactant particles increases

Question 11

why does a higher concentration of reactant give you more product

Answer 11

because we started with more reactant molecules

Question 12

what effect does surface area have on rate of reaction

Answer 12

increasing the surface area increases the rate of reaction

Question 13

why does increasing surface area have that effect on rate of reaction

Answer 13

because smaller sized blocks of a solid reactant have a greater surface volume to ratio than larger blocks, this means they have more particles on the surface, meaning there are more collisions per second

Question 14

how to investigate the effect of surface area on ror

Answer 14

1. Use same setup and HCL and magnesium practical
   2 . Instead of mg, use a marble chip
2. measure the volume of carbon dioxide gas produced and use it to determine the ror
3. change the surface area of marble chips

Question 15

effect of temperature on ror and why

Answer 15

increasing temperature increases the rate of reaction, this is because increasing temperature increases the particle’s energy
- because the particles have more energy, they move faster
- this increases the frequency of collisions and each collision has more energy
- so more particles can overcome the activation energy barrier and collide successfully

Question 16

what are catalysts

Answer 16

things that increase the rate of chemical reaction without being used up during the reaction

Question 17

benefits of catalysts

Answer 17

• they allow us to carry out reactions quickly without needing to increase the temperature and this saves money
• they can be reused

Question 18

how do catalysts increase the rate of reaction

Answer 18

they provide a different pathway for the reaction that has a lower activation energy

• They lower the activation energy. This means that more particles can successfully collide per second.

Question 19

why do we not include catalysts in a chemical equation

Answer 19

because they are not used up so they arent a reactant

Question 20

what is equilibrium

Answer 20

when reactants are placed in a place that stops reactants and products from escaping , and the forward and reverse reactions take place at the same rate

Question 21

What does Le Chatelier’s principle state

Answer 21

that if a system is at equilibrium, and a change is made to the conditions, then the system responds to counteract this change

Question 22

what happens in a reaction that is exothermic

Answer 22

temperature if system increases

Question 23

what happens in a reaction that is endothermic

Answer 23

temperature of system decreases

Question 24

what happens when temperature is increased in an equilibrium

Answer 24

the equilibrium shifts to whichever reaction is endothermic, as energy is taken in, which will cause the temperature to fall

Question 25

what happens when temperature decreases in an equilibrium

Answer 25

the equilibrium shifts to whichever side of the reaction is exothermic, as energy is released, causing the temperature to increase

Question 26

what does the pressure of a gas depend on

Answer 26

the number of molecules

Question 27

what happens when you increase the pressure in an equilibrium

Answer 27

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

Question 28

what happens if you decrease the pressure of an equilibrium

Answer 28

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

Question 29

the steeper the slope…

Answer 29

the faster the reaction

Question 30

why, gradually, does the line becomes less steep in a rate of reaction graph

Answer 30

because a lot of the reactant molecules have already reacted and turned into product, meaning there are fewer reactant molecules to collide and react

Question 31

how to determine rate of reaction using how much co2 is lost

Answer 31

• Place the reaction on a balance
• as co2 is produced, the mass decreases
• this can be used to find ror

Question 32

hydrated copper sulfate can be turned into what

Answer 32

anhydrous copper sulfate, which is white, and water

• forward reaction is endo

Question 33

what is a hypothesis

Answer 33

a proposal that could explain a fact or an observation