Respuesta :
Given:
PCl3 + 3H2O → H3PO3 + 3HCl
Mass of HCl = 42.9 g
Mass of PCl3 = 62.0 g
To determine:
% yield of HCl
Explanation:
Molar mass of PCl3 = 137 g/mol
# moles of PCl3 reacted = mass/molar mass = 62 g/137 g.mol-1 = 0.453 moles
Based on the reaction stoichiometry:
1 mole of PCl3 produces 3 moles of HCl
therefore, 0.453 moles of PCl3 would be expected to produce: 0.453 * 3 = 1.359 moles of HCl
Molar mass of HCl = 36 g/mol
Therefore, expected mass (theoretical yield) of HCl = # moles of HCl * molar mass
= 1.359*36 = 48.92 g
% yield = (actual yield/theoretical yield)*100
% yield of HCl= (42.0/48.92)*100 = 85.9 %
Ans: (C)
Answer : The correct option is, (C) 85.0 %
Solution : Given,
Mass of [tex]PCl_3[/tex] = 62 g
Experimental yield of HCl = 42 g
Molar mass of [tex]PCl_3[/tex] = 137 g/mole
Molar mass of HCl = 36.5 g/mole
First we have to calculate the moles of [tex]PCl_3[/tex].
[tex]\text{Moles of }PCl_3=\frac{\text{Mass of }PCl_3}{\text{Molar mass of }PCl_3}=\frac{62g}{137g/mole}=0.452moles[/tex]
Now we have to calculate the moles of HCl.
The balanced chemical reaction is,
[tex]PCl_3+3H_2O\rightarrow H_3PO_3+3HCl[/tex]
From the balanced reaction we conclude that
As, 1 moles of [tex]PCl_3[/tex] react to give 3 moles of [tex]HCl[/tex]
So, 0.452 moles of [tex]PCl_3[/tex] react to give [tex]3\times 0.452=1.356[/tex] moles of [tex]HCl[/tex]
Now we have to calculate the mass of HCl.
[tex]\text{Mass of }HCl=\text{Moles of }HCl\times \text{Molar mass of }HCl[/tex]
[tex]\text{Mass of }HCl=(1.356mole)\times (36.5g/mole)=49.494g[/tex]
Therefore, the mass of HCl is, 49.494 g
Now we have to calculate the percent yield of HCl.
[tex]\%\text{ yield of }HCl=\frac{\text{Actual yield of }HCl}{\text{Theoretical yield of }HCl}\times 100=\frac{42g}{49.494g}\times 100=84.85\%=85.0\%[/tex]
Therefore, the percent yield of HCl is, 85.0 %
