C4.3/C4.4/C4.5/C4.6/C4.9 - Chemical Calculations

Question 1

limiting reactant

Answer 1

-reactant that gets used up first in a reaction
-lower quantity of moles

Question 2

yield

Answer 2

mass of product that a chemical reaction produces

Question 3

percentage yield

Answer 3

-actual mass of desired product/ theoretical max mass of desired product x 100

Question 4

factors affecting percentage yield (5)

Answer 4

-reactions may be reversible
-unwanted products produced
-products lost in transit
-reactants may be impure
-product lost in during its separation from reactant mixture

Question 5

atom economy

Answer 5

a measure of the amount of starting materials that end up as useful products

Question 6

why is it important to maximise atom economy in industries

Answer 6

-to conserve Earth’s resources
+ minimise pollution

Question 7

why is it important to maximise atom economy in industries

Answer 7

-to conserve Earth’s resources
+ minimise pollution

Question 8

work out percentage atom economy

Answer 8

-Mr from desired product/ sum of Mr of reactant from equation x 100

Question 9

concentration

Answer 9

-g/dm3
-amount of solute/volume of solution

Question 10

dm3 to cm3

Answer 10

x 1000

Question 11

increase concentration

Answer 11

-add more solute
-evaporate solution

Question 12

volume of 1 mol of any gas

Answer 12

24 dm3
-at 20 .c and 1 atmosphere

Question 13

24dm3 per mole

Answer 13

molar gas volume

Question 14

number of moles of gases =

Answer 14

volume of gas /24dm3

Question 15

ratio of number of moles of gas in balanced equation =

Answer 15

-ratio of volume of gas involved
-same value

Question 16

mole/dm3 to g/dm3

Answer 16

Multiply by mr value