Question

Mg(s) + HCl (aq) ---> MgCl2(aq) + H2(g) Consider the above unbalanced equation. What volume of H2 is produced at 340 mm Hg and 73.4°C when 0.86 g of Mg reacts with excess HCl? Use molar masses with at least as many significant figures as the data given

Answer 1

Mg + 2 HCl —> MgCl2 + H2

Molar mass of Mg = 24.31 g/mol

mass of Mg = 0.86 g

mol of Mg = (mass)/(molar mass)

= 0.86/24.31

= 0.0354 mol

From balanced chemical reaction, we see that

when 1 mol of Mg reacts, 1 mol of H2 is formed

mol of H2 formed = moles of Mg

= 0.0354 mol

we have:

P = 340.0 mm Hg

= (340.0/760) atm

= 0.4474 atm

n = 0.0354 mol

T = 73.4 oC

= (73.4+273) K

= 346.4 K

we have below equation to be used:

P * V = n*R*T

0.4474 atm * V = 0.0354 mol* 0.0821 atm.L/mol.K * 346.4 K

V = 2.3 L

Answer: 2.3 L