Question

what concentration of zinc chloride solution is produced when 0.5065g of zinc is reacted with 100.0mL of 0.1260 M hydrochloric acid. Assume the total volume of the solutions is 100.0mL

Answer 1

Zn(s) + 2HCl(aq)--------> ZnCl2(aq) + H2(g)

0.1260M HCl = 0.1260 mole HCl in 1000ml

So, in 1000ml no of mole of HCl = 0.0126 mole

Molar mass of Zn = 65.38g/mole

Mass of Zn = 0.5065g

no of moles of Zinc = mass/molar mass = 0.5065/65.38 = 0.00775mole

1mole of Zn require 2 mole of HCl

0.00775 mole of Zn require 0.0155 mole of HCl but actual mole of HCl is 0.0126. So , HCl is limiting and Zn is excess

2 mole of HCl give 1 mole of ZnCl2

0.0126 mole of HCl give 0.0063 mole of ZnCl2

0.0063 mole of ZnCl2 in 100ml

Therefore, Concentration of ZnCl2 = (0.0063mole/100ml)×1000ml = 0.063M

Therefore, concentration of ZnCl2 = 0.063M