Question

8.41: Can explain this to me?

Hydrobromic acid dissolves solid iron according to the following reaction Fe(s) + 2 HBr(aq) → FeBr(aq) + H2(g)

Answer 1

Fe(s) + 2 HBr (aq) ======> FeBr₂ (aq) +H₂(g)

Part A

Step-1 Calculate moles of Fe

Molar mass of Fe is 55.8450 g/mol

Weight of iron =3.4g iron

Moles of Iron = 3.4g/ 55.8450 g/mol = 0.06088 moles

Step-2 Calculate moles of HBr

1 mol of Fe is reacted with 2 moles of HBr

So, 0.06088 moles of Fe is reacted with 2 x 0.06088 moles of HBr = 0.12176 moles of HBr

Step-3 Calculate mass of HBr

Molar mass of HBr is 80.9119 g/mol

Mass of HBr = Moles of HBr x Molar mass of HBr

Mass of HBr = 0.12176 moles x 80.9119 g/mol = 9.85g

Mass of HBr = 9.9 g (2sig. fig.)

Part B

1 mol of Fe is produces with 1 moles of H₂

So, 0.06088 moles of Fe produces with 0.06088 moles of H₂

Molar mass of H₂ = 2.01588g/mol

Mass of H₂ = Moles of H₂ x Molar mass of H₂

Mass of H₂ = 0.06088 moles x 2.01588g/mol = 0.12 g

Mass of H₂ = 0.12 g (2sig. fig.)