Calculations

Question 1

Calculate the relative atomic mass of gallium when it is 60% gallium-69 and 40% gallium-71

Answer 1

69.8

Question 2

Calculate the relative formula mass of Ca(NO3)2

Answer 2

164

Question 3

Calculate the mass of hydrogen produced when 0.5g of lithium metal is added to water.

Answer 3

0.072g

Question 4

26.9g of copper chloride CuCl2 is dissolved in 125cm cubed of water. Calculate the concentration of the solution in mol dm-3.

Answer 4

1.6dm-3

Question 5

How do you calculate atom economy?

Answer 5

Total Mr of desired product / total Mr of all products x 100

Question 5

How do you calculate percentage yield?

Answer 5

Actual yield / theoretical yield x 100

Question 6

How do you calculate the amount of a gas?

Answer 6

Amount = volume of gas / molar volume

Question 7

How do you calculate the mass of a gas?

Answer 7

Mass = Mr x amount