Chemistry difficult questions

Question

A 50.0 g piece of impure zinc reacts with 129.0 cm3 hydrochloric acid (HCl solution) (density = 1.18 g/ cm3 ; 35.0 % by mass). Calculate the % of pure zinc in the piece.

Treat an aluminium sheet with 50.0 mL of a hot and concentrated H2SO4 solution (density = 1.65 g/mL ; 73.8 % by mass). How many litres of SO2(gas) are formed, measured at 25.0 °C and 1005 mbar? 2 Al + 6 H2SO4 -> Al2(SO4)3 + 3 SO2+ 6 H2O

could u pls explain these 2 exercises

Answer 1

First part, there isn't enough information provided. No results of the reaction are given.

Second part, you have the balance equation 2Al + 6H₂SO₄ ==> Al₂(SO₄)₃ + 3SO₂ + 6H₂O

To find L of SO2 produced, we first want to find the moles of SO2 and then use the Ideal Gas Law to find L.

The SO2 derives from the H2SO4, so we can work with that alone.

50 ml H2SO4 x 1.65 g/ml = 82.5 g H2SO4 but since it is only 73.8% pure, that equates to 60.9 g H2SO4

moles H2SO4 = 60.9 g H2SO4 x 1 mol/98 g = 0.621 moles H2SO4

moles SO2: 0.621 mol H2SO4 x 3 mol SO2/6 mol H2SO4 = 0.31 mol SO2

Using PV = nRT and solving for V, we have...

V = nRT/P = (0.31 mol)(0.0831 Lbar/Kmol)(298K)/1.005 bar

V = 7.65 L SO2