Question

if 2.5 moles of zinc react with 6.0 moles of hydrochloric acid Zn + 2HCl → ZnCl2 + Hz, find mass of zinc chloride . Zn (A=65.3) Cl (A=35.5) ? b) 136g c) 160g d) 165 g a) 140 g​

Answer 1

Zn

Zn+2HCl→ZnCl

2

+H

2

1 mole of Zn reacts with 2 moles of HCl.

2.5 moles of Zn will react with 2×2.5=5.0 moles of HCl.

However 6.0 moles of HCl are present.

Thus, HCl is the excess reactant and Zn is the limiting reactant.

Answer 2

Given:

The number of moles of zinc = 2.5 moles

The  number of moles of hydrochloric acid = 6 moles

The reaction: Zn + 2HCl → ZnCl₂ + H₂

To Find:

The mass of zinc chloride formed

Solution:

The mass of zinc chloride produced is 340g.

According to the given reaction, 2 moles of hydrochloric acid react with 1 mole of zinc metal to produce 1 mole of zinc chloride.

So 2.5 moles of zinc will require 2.5 X 2 moles of HCl

= 5 moles of HCl

But given that HCl = 6 moles

⇒ Zn is the limiting reagent.

If 1 mole of zinc metal produces 1 mole of zinc chloride

⇒ Using the unitary method, 2.5 moles of zinc will form 2.5 moles of zinc chloride.

The molecular mass of ZnCl₂ = 1 X Mass of Zn + 2 X Mass of Cl

= 65.3 + 2 X 35.5

= 136.3 g

So the mass of 2.5 moles ZnCl₂ = 2.5 X 136.3

= 340 g