Question

What volume of HCl solution of density 1.2 g/cm and containing 36.5% by weight HCl, must
be allowed to react with zinc (Zn) in order to liberate 4.0 g of hydrogen ?
(a) 333.33 mL (b) 500 mL
(c) 614.66 ml (d) None of these
*please provide step by step explanation*​

Answer 1

What volume of HCl solution should be added?

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Density of HCl solution == 1.2 d/cm³

weight percentage == 36.5%

amount of hydrogen to be liberated == 4g

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step by step explanation :

Write and balance the equation.

Zn + 2HCl ==> H2 + ZnCl2

Zn + 2HCl ==> H2 + ZnCl2How many mols of H2 do you want to generate.

no. of mols = grams/molar mass

amount of H2 = 4g.

molar mass H2 = 1*2 = 2 g/mol.

no. of moles of H2 = 4g/2 = 2 mols

therefore, 2 moles ofH2 in 4g of H2

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Now convert mols H2 to mols HCl.

That is done with the coefficient in the balanced equation.

2 mols H2 x (2 mols HCl/1 mol H2) = 4 mols of HCl.

To obtain 4g of H2 (2 mol) you will need 4 mols HCl.

H2 (2 mol) you will need 4 mols HCl.How much 12 M HCl does it take to get 4 mol HCl?

Mass of HCl = mols HCl/L HCl or rearrange to L HCl = mols HCl/M HCl.

mols HCl = 4

Mass of HCl = 12

L HCl = 4/12 = .3333L = 333.3 mL.

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$hope \: you \: understood....$