Question

How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl? (Atomic weight of Pb = 207)
 \[PbO + 2HCl \to PbC{l_2} + {H_2}O\]
A.0011
B.0.029
C.0.044
D.0.333

Answer 1

Hint: To solve this question, we must first calculate the molecular mass of the reactants. Then we must calculate the number of moles of the reactants present. the number of moles of PbO would directly correspond to the number of moles of lead (II) chloride formed. Hence, we derive a relation between the number of moles of both these compounds and find the answer.

Complete Step-by-Step Answer:

Before we move forward with the solution of this question, let us first understand the data that has been given to us:
To carry out the given reaction between PbO and HCl, 6.5 g of PbO and 3.2 g of HCl are used. We must also note that the atomic masses of the elements involved in this reaction are –
Pb = 207 g/mol; O = 16 g/mol; H = 1 g/mol; Cl = 35.5 g/mol.
To move forward with the solution, we must first calculate the number of molecular masses of both the reactants, and then we must calculate their number of moles.
Molecular mass of PbO = (1) (molecular mass of Pb) + (1) (molecular mass of O)
                \[ = \left( 1 \right)\left( {207} \right) + \left( 1 \right)\left( {16} \right)\]
               = 223 g/mol
Molecular mass of HCl = (1) (Molecular mass of H) + (1) (molecular mass of Cl)
                        \[ = \left( 1 \right)\left( 1 \right) + \left( 1 \right)\left( {35.5} \right)\]
                        = 36.5 g/mol
The number of moles of a substance can be calculated as:
number of moles \[ = \dfrac{{mass\,\,of\,\,the\,\,given\,\,sample}}{{molecular\,\,mass\,\,of\,\,the\,\,subs\tan ce}}\]
Hence,
Number of moles of PbO = \[\dfrac{{6.5}}{{223}}\] = 0.029 moles
Number of moles of HCl = \[\dfrac{{3.2}}{{36.5}}\] = 0.088 moles
We can see that for the given reaction, PbO is limiting reagent. And one mole of PbO corresponds to the formation of one mole of lead (II) chloride. Hence, by this ratio, 0.029 moles of PbO can form 0.029 moles of lead (II) chloride.
Hence, Option B is the correct option

Note: The limiting reagent (or limiting reactant or limiting agent) in a chemical reaction is a reactant that is totally consumed when the chemical reaction is completed. The amount of product formed is limited by this reagent, since the reaction cannot continue without it.