C5 Monitoring and Controlling Chemical Reactions

Question 1

What is atom economy

Answer 1

The atom economy is a measure of how many atoms in the products make up the desired product.

Question 2

What is the formula used to calculate atom economy

Answer 2

𝐴𝑡𝑜𝑚 𝑒𝑐𝑜𝑛𝑜𝑚𝑦= (Sum of 𝑀𝑟 𝑜𝑓 𝑑𝑒𝑠𝑖𝑟𝑒𝑑 𝑝𝑟𝑜𝑑𝑢𝑐𝑡/Sum of 𝑀𝑟 𝑜𝑓 𝑎𝑙𝑙 𝑝𝑟𝑜𝑑𝑢𝑐𝑡s) x 100

Question 3

What factors should be considered when making a substance?

Answer 3

Yield of the product
Atom economy
Usefulness of bi-products
Rate of reaction
Equilibrium position if reversible

Question 4

What is Theoretical Yield

Answer 4

The theoretical yield is the maximum possible mass of desired products you can make from a given mass of reactants.

Question 5

What is percentage yield

Answer 5

The percentage yield is the amount produced compared to your theoretical yield

Question 6

How do you calculate percentage yield ?

Answer 6

𝑝𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑦𝑖𝑒𝑙𝑑= (𝑎𝑐𝑡𝑢𝑎𝑙 yield) / (𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑚𝑎𝑠𝑠) 𝑥 100

Question 7

The equation for concentration

Answer 7

𝑪𝒐𝒏𝒄𝒆𝒏𝒕𝒓𝒂𝒕𝒊𝒐𝒏= 𝑨𝒎𝒐𝒖𝒏𝒕/𝑽𝒐𝒍𝒖𝒎𝒆

Question 8

Give units for concentration

Answer 8

g/dm3 or mol/dm3

Question 9

What pieces of equipment are needed to carry out a titration

Answer 9

Burette, volumetric pipette, pipette filler, conical flask, white tile, clamp and stand, indicator.

Question 10

What are concordant titre values

Answer 10

When the titre values are within 0.10 cm3

Question 11

What is molar volume

Answer 11

1 mole of any substance in the gas state occupies the same volume at the same temperature and pressure
At room temperature and pressure (RTP) this volume is 24dm3 or 24000cm3

Question 12

Write down the gas equations

Answer 12

𝑎𝑚𝑜𝑢𝑛𝑡 (𝑚𝑜𝑙)= (𝑣𝑜𝑙𝑢𝑚𝑒 (𝑑𝑚3))/24

𝑣𝑜𝑙𝑢𝑚𝑒 (𝑑𝑚3 )=𝑎𝑚𝑜𝑢𝑛𝑡 (𝑚𝑜𝑙) 𝑥 24

Question 13

What is rate of reaction

Answer 13

Measure of how quickly reactants are used or products are formed

Question 14

Give formulae for measuring rate

Answer 14

𝑅𝑎𝑡𝑒 𝑜𝑓 𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛= (𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑝𝑟𝑜𝑑𝑢𝑐𝑡 𝑝𝑟𝑜𝑑𝑢𝑐𝑒𝑑)/𝑇𝑖𝑚𝑒

𝑅𝑎𝑡𝑒 𝑜𝑓 𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛= (𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑟𝑒𝑎𝑐𝑡𝑎𝑛𝑡 𝑢𝑠𝑒𝑑)/𝑇𝑖𝑚𝑒

Question 15

What has to happen in order for a reaction to happen between 2 particles

Answer 15

The reacting particles need to collide
The collision needs to have enough energy (more than the activation energy) so that the particles will then react (bonds will break etc)

Question 16

Predict what will happen in terms of collisions if we increase the temperature of a reaction

Answer 16

The number of collisions increase because the particles are moving more quickly.
The percentage of collisions which are successful increases because all the particles have more energy

Question 17

What is a catalyst?

Answer 17

A substance that increases the rate of the reaction but remains unchanged at the end.
They provide an alternative reaction pathway with a lower activation energy.

Question 18

What is a reversible reaction

Answer 18

A reversible reaction is one in which the products are able to react with each other to change back into the reactants without any additional changes

Question 19

Give an example of a reversible reaction

Answer 19

CuSO4.5H2O ↔ CuSO4 + 5H2O

Question 20

What is the equilibrium position

Answer 20

The position of equilibrium is related to the ratio of the concentration of products to the concentration of reactants

Question 21

State if true or false for the following:
At equilibrium reactants are still reacting to make products.
At equilibrium you always have equal amounts of reactants and products.
Equilibrium always happens at the same point no matter the conditions.
When you decrease the concentration of the reactants the equilibrium point will be closer to the left.
Equilibrium can only be reached in a closed system.

Answer 21

At equilibrium reactants are still reacting to make products TRUE
At equilibrium you always have equal amounts of reactants and products FALSE
Equilibrium always happens at the same point no matter the conditions FALSE
When you decrease the concentration of the reactants the equilibrium point will be closer to the left TRUE
Equilibrium can only be reached in a closed system TRUE

Question 22

What is Le Chatelier’s Principle?

Answer 22

Any change made to a reaction which is in equilibrium, will result in the equilibrium position moving to minimise the change made

Question 23

What factors might change the position of equilibrium?

Answer 23

Temperature
Concentration
Pressure

Question 24

What is dynamic equilibrium

Answer 24

The forward and backward reactions still happen and concentrations of all the reacting substances remain constant