I think you mean:
".. reacts with oxygen gas to produce lead (II) oxide and 'sulfur' dioxide..."
The balanced chemical reaction would be
2PbS + 3O2 --> 2PbO + 2SO2
The stiochiometric ratio is this: 3 moles of O2 produces 2 moles of lead (II) oxide. So,
0.500 moles (2/3) = 0.333 moles
Therefore, 0.333 moles of PbO is produced when 0.500 moles of O2 reacts with PbS.
<u>We are given:</u>
Initial Temperature = 90°c
Final Temperature = 120°c
Heat applied(ΔH) = 500 Joules
Specific heat(c) = 0.9 Joules / g°C
Mass of Aluminium(m) = ?
<u>Change in temperature:</u>
ΔT = Final temp. - Inital Temp.
ΔT = 120 - 90
ΔT = 30°c
<u>Calculating the mass:</u>
We know the formula:
ΔH = mcΔT
replacing the values:
500 = m(0.9)(30)
500 = m(27)
m = 500/27
m = 18.52 grams
