How many mole of lead chloride will be formed from a reaction between 6.5 grams of PbO and 3.2 grams of HCl ?
A balanced equation for the above reaction is :
PbO + 2HCl ---------------> PbCl2 + H2O
Now,we see that PbO and HCl react in 1:2 mol ratio.
Atomic mass of PbO = Atomic mass of Pb + Atomic mass of O
= (206.9 + 16) g = 222.9
Atomic mass of HCl = Atomic mass of H + Atomic mass of Cl
= ( 1.008 + 35.45 ) g = 36.45g
moles of PbO = 6.5g / 222.9g = 0.029 = 0.03
moles of HCl = 3.2g / 36.45g = 0.08
Since we need only 0.06 mol HCl to react with 0.03 mol PbO
As we can see,we have too much HCl so PbO is the limiting reagent. This just means that the amount of product will be determined by the amount of PbO.
Now, from each mol of PbO we get 1 mol of PbCl2. Since we started with 0.03 mol PbO, we only form 0.03 moles of PbCl2.