Roasting galena [lead(II) sulfide] is an early step in the industrial isolation of lead. How many liters of sulfur dioxide, measured at STP, are produced by the reaction of 6.61 kg of galena with 154 L of oxygen gas at 220°C and 2.00 atm? Lead(II) oxide also forms.

Answer : The volume of sulfur dioxide measured at STP is, 113.6 L

Explanation :

First we have to calculate the moles of PbS.

Molar mass of PbS = 239.27 g/mol

Now we have to calculate the moles of oxygen gas.

Using ideal gas equation:

where,

P = Pressure of gas = 2.00 atm

V = Volume of gas = 154 L

n = number of moles  = ?

R = Gas constant =

T = Temperature of gas =

Putting values in above equation, we get:

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction will be:

From the balanced chemical reaction we conclude that,

As, 3 moles of react with 2 moles of PbS

So, 7.61 moles of react with moles of PbS

From this we conclude that, is an excess reagent because the given moles are greater than the required moles and is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of

From the reaction, we conclude that

As, 3 mole of react to give 2 mole of

So, 7.61 mole of react to give mole of

Now we have to calculate the volume of  at STP.

Using ideal gas equation:

where,

P = Pressure of gas = 1.00 atm

V = Volume of gas = ?

n = number of moles  = 5.07 mol

R = Gas constant =

T = Temperature of gas = 273 K

Putting values in above equation, we get:

Thus, the volume of sulfur dioxide measured at STP is, 113.6 L

- lead + phosphoric acid = hydrogen + lead(ii) phosphate