Calculate the number of moles in 23.0g of CO2? ( relative atomic mass : Carbon=12, Oxygen=16)

Firstly we need to work out the molecular mass of CO₂ . There is one carbon and two oxygens so we have to add the relative atomic mass (Ar) of one carbon and two oxygens. From the question we know the A_r of Oxygen and Carbon so the relative formula mass (M_r) of CO₂ is : RMM= 12 + (16 X 2) = 44g/mol
Using the equation m=M_r x n We can work out the number of moles but first we have to rearrange the equation to give n on one side. So divide both sides to give : m/M_r=n From the question we know the mass of CO2 and the Mr ,so plug these into the equation to give a value for n.
23g/44g/mol=0.52 moles ( given to 2 significant figures)