The balanced symbol equation for the reaction is: $Pb\left(NO_3\right)_2\left(aq\right)\ +\ 2NaI\left(aq\right)\ \rightarrow\ PbI_2\left(s\right)\ +\ 2NaNO_3\left(aq\right)$  
The student uses 2.4g of lead nitrate. The total mass at the end of the reaction is 3.9g. Calculate the mass of sodium iodide used.

(a)  

What is the relative atomic mass of magnesium? The isotopes of magnesium and their percentage abundances are: ²⁴Mg 78.6%, ²⁵Mg 10.1%, ²⁶Mg 11.3%.

(a)  

What is the mass of 0.1 moles of sulphur dioxide molecules, SO₂?

(a)  

Calculate the number of moles of CH₄ molecules in 3.2 g of methane.

(a)  

Calculate the percentage yield for a reaction where the actual yield is 3.2 and the theoretical yield is 4.0g.

(a)  

Calculate the atom economy for making iron in this reaction: $Fe_2O_3\ +3CO\ \rightarrow\ 2Fe\ +3CO_2$  


(a)  

Zinc sulphate, ZnSO4, can be made by reacting zinc carbonate with sulphuric acid. Calculate the atom economy for making zinc sulphate in this way. $ZnCO_3\ +H_2SO_4\ \rightarrow\ ZnSO_4\ +H_2O\ +CO_2$  


(a)  

Use the equation below to calculate the maximum volume at rtp, in dm3, of hydrogen that can be produced from 4.6g of sodium. $2Na\left(s\right)\ +2H_2O\left(l\right)\ \rightarrow\ 2NaOH\left(aq\right)\ +H_2\left(g\right)$  


(a)  

What mass of calcium chloride is produced when 3.7g of calcium hydroxide reacts with an excess of hydrochloric acid?  $Ca\left(OH\right)_2\ +2HCl\ \rightarrow\ CaCl_{2\ }+2H_2O$  


(a)  

9.2g of sodium was reacted with 7.2g of water to form sodium hydroxide and hydrogen. Calculate the volume of hydrogen produced in cm³.

(a)  

Calculate the volume of 220g of carbon dioxide at room temperature and pressure. Give your answer in dm³.

(a)  

Aspirin (C9H8O4) can be made by reacting salicylic acid with ethanoic anhydride as per the equation below. Calculate the atom economy for this reaction. $C_7H_6O_3\ +C_4H_6O_3\ \rightarrow\ C_9H_8O_4\ +CH_3COOH$  


(a)