chemistry c6

Question 1

what is a catalyst

Answer 1

a catalyst speeds up the rate of reaction by providing a alternative route with a lower activation energy it is chemically unchanged at the end of the reaction

Question 1

write a balanced symbol equation for the Haber process

Answer 1

N2(g)+3H2 (g)⇌ 2NH3 (g)

Question 2

what is activation energy

Answer 2

the energy required to break bonds and start the reaction

Question 3

how can we measure the rate of reaction of a reaction that produces a gas

Answer 3

by measuring the volume of gas produced or the mass lost

Question 4

how can we work out the rate of reaction from a graph of volume of gas vs time

Answer 4

calculating the gradient of the tangent to the curve

Question 5

explain what happens to the position of the equilibrium when you decrease the temperature ( exo)

Answer 5

the position of the equilibrium moves in the direction of the exothermic reaction

Question 6

explain how the surface area changes the rate of reaction

Answer 6

increasing the surface area means more frequent collisions and a higher rate of reaction

Question 7

write the word equation for the haber process

Answer 7

nitrogen + hydrogen —–> ammonia

Question 8

what is the symbol for a reversible reaction

Answer 8

⇌

Question 9

how can we identify a catalyst in a reaction
(speeds ip…)

Answer 9

it speeds up the rate of reaction and doesn’t get used up

Question 10

why don’t industrial synthesis every use very high pressures

Answer 10

too dangerous and equipment is too expensive

Question 11

why dont industrial synthesis ever use very high temperatures
( energy)

Answer 11

requires to much energy

Question 12

explain what happens to the position of a equilibrium when you add a product

( l to re)

Answer 12

the position of equilibrium moves to the left to remove some of these products

Question 13

explain how catalysts change the rate of a reaction
(decrease activation energy)
(energy greater than…)

Answer 13

catalyst decrease the activation energy so there are more frequent successful collisions with energy greater than the activation energy

Question 14

what is the biggest source of error when your measuring the volume of gas produced

( reaction vessle)

Answer 14

gas lost before the top is put on the reaction vessel

Question 15

explain what happens to the position of equilibrium when you increase the temperature

Answer 15

the position of the equilibrium moves in the direction of the endothermic reaction

Question 16

if a reaction forms a principatee how can we measure the rate

Answer 16

measure the time it takes for a cross placed under the reaction to disappear calculate 1/time to find the rate

Question 17

explain what happens to the position of the equilibrium when you remove a product

Answer 17

the position of the equilibrium moves to the right to add more products

Question 18

what can we use to measure the volume of gas produced

Answer 18

gas syringe or upside down measuring cylinder full of water

Question 19

explain how concentration changes the rate of reaction

Answer 19

increasing the concentration means more particles in the same volume more frequent collisions and a high rate of reactions

Question 20

explain what happens to the position of equilibrium when you decrease the pressure
(less pressure more moles )

Answer 20

the position of the equilibrium moves to the side with more moles of gas

Question 21

explain how particle size changes the rate of a reaction

Answer 21

smaller particle size means higher surface area , more frequent collisions and a higher rate of reaction

Question 22

why don’t reversible reactions in a closed system produce 100% yield

Answer 22

at equilibrium there is a mixture of reactants and products

Question 23

explain how temperature changes the rate of reactions
( fast ,energy,energy> active energy)

Answer 23

increasing temperature means particles move faster and with more energy so there are more frequent successful collisions with energy greater than the activation energy

Question 24

explain what happens to the position of the equilibrium when you remove a reactant

(L to +)

Answer 24

the position of equilibrium moves to the left to add more reactants

Question 25

what is ammonia used for

Answer 25

fertilisers

Question 26

explain what happens to the position of equilibrium when you add a reactant
(r)

Answer 26

the position of the equilibrium moves to the right to remove some of these reactants

Question 27

what are two characteristics of dynamic equilibrium

Answer 27

the concentrations of the reactants and products are constant . the rate of the forward and backward reactions are equal

Question 28

what can be used to measure the mass lost during a reaction
(MB)

Answer 28

mass balance

Question 29

explain what happens to the position of the equilibrium when you increase the pressure(fewer moles)

Answer 29

the position of the equilibrium moves to the side with fewer moles of gas

Question 30

explain how pressure changes the rate of a reaction

( more p more c more r)

Answer 30

increasing the pressure means more particles in the same volume , more frequent collisions and a higher rate of reactions