Question

Small amounts of hydrogen gas are often produced by reaction of zinc with HCl; Zn(s) + 2 HCl(aq) ® H2(g) + ZnCl2(aq) How many liters of H2 gas, collected over water at a pressure of 445.8 mm Hg and temperature of 20.00 °C (The vapor pressure of water at this temperature is 17.54 mm Hg.) will be produced by the reaction of 1.815 g of Zn with an excess of HCl?

Answer 1

Zn   + 2HCl--------> ZnCl2 + H2

1 mole of Zn react with HCl to gives 1 moles of H2

65.4g of Zn react with HCl to gives 2g of H2

1.815g of Zn react with HCl to gives = 2*1.815/65.4 = 0.0555g of H2

PT   = PH2 + PH2O

PH2 = PT-PH2O

        = 445.8-17.54 = 428.26mmHg    = 428.26/760 = 0.5635atm

T    = 20C⁰ = 20+273 = 293K

W   = 0.0555g

M   = 2

PV = nRT

n = W/M

PV = WRT/M

V   = WRT/PM

    = 0.0555*0.0821*293/0.5635*2

     = 1.185L >>>> answer