Answer A: Connect a wire coil to an ammeter. Move a bar magnet into and out of the wire coil as you observe the ammeter.
The reaction of iron sulfide (FeS) with hydrochloric acid (HCl) results in the formation of ferrous chloride (FeCl2) and hydrogen sulfide (H2S) gas. The reaction can be shown as follows:
FeS (s) + HCl(aq) ---- FeCl2(s) + H2S(g)
The bubbles indicate the formation of H2S gas which is a chemical change. The formation of bubbles indicates this change as it suggests that the reactants are combing to form products i.e. it signals a chemical reaction.
Molarity can be defined as the number of moles of solute in 1 L solution.
Molarity of Na₂SO₄ solution - 0.200 M
this means there are 0.200 moles in 1 L solution
Molar mass of Na₂SO₄ - 142 g/mol
therefore mass of Na₂SO₄ in 1.00 L - 0.200 mol x 142 g/mol = 28.4 g
a mass of 28.4 g of Na₂SO₄ is present in 1.00 L
