How many grams of pure H2SO4 can be obtained from 250 grams of iron ore if the ore is 82% FeS2? The reactions involved are given below:

4FeS2 + 11 O2 --> 2 Fe2O3 + 8 SO2 (95% efficient)
2SO2 + O2 --> 2SO3 (90% efficient)
SO3 + H2O --> H2SO4 (90% efficient)

To find the number of grams of pure H2SO4 obtained from 250 grams of iron ore, we need to follow these steps:

Step 1: Calculate the mass of FeS2 in the iron ore.
Since the ore is 82% FeS2, we can calculate the mass of FeS2 by multiplying the total mass of the ore (250 grams) by the percentage of FeS2:
Mass of FeS2 = 82% × 250 grams = 0.82 × 250 grams = 205 grams

Step 2: Calculate the moles of FeS2.
To do this, we need to know the molar mass of FeS2, which is:
Molar mass of FeS2 = (molar mass of Fe) + 2 × (molar mass of S)
Molar mass of FeS2 = (55.845 g/mol) + 2 × (32.06 g/mol) = 119.95 g/mol

Next, we can calculate the moles of FeS2 using the formula:
Moles of FeS2 = Mass of FeS2 / Molar mass of FeS2
Moles of FeS2 = 205 grams / 119.95 g/mol ≈ 1.709 moles

Step 3: Calculate the moles of SO3 produced.
From the balanced equations provided, we see that for every 8 moles of SO2, we get 2 moles of SO3. Using this ratio, we can calculate the moles of SO3:
Moles of SO3 = (1.709 moles SO2) × (2 moles SO3 / 8 moles SO2) = 0.42725 moles

Step 4: Calculate the mass of H2SO4 produced.
Since 1 mole of SO3 reacts with 1 mole of H2O to produce 1 mole of H2SO4, we can say that the moles of H2SO4 produced are equal to the moles of SO3:
Moles of H2SO4 = 0.42725 moles

Now, let's calculate the molar mass of H2SO4:
Molar mass of H2SO4 = (2 × molar mass of H) + (molar mass of S) + (4 × molar mass of O)
Molar mass of H2SO4 = (2 × 1.00784 g/mol) + 32.06 g/mol + (4 × 15.999 g/mol) = 98.086 g/mol

Finally, we can calculate the mass of H2SO4 using the formula:
Mass of H2SO4 = Moles of H2SO4 × Molar mass of H2SO4
Mass of H2SO4 = 0.42725 moles × 98.086 g/mol ≈ 41.9 grams

Therefore, approximately 41.9 grams of pure H2SO4 can be obtained from 250 grams of iron ore.

250 x 0.82 = estimated 205 g starting FeS2. Convert 205 g to mols = about 2 mol but you should confirm that.

Then mols H2SO4 = 2 mols FeS2 x (8 mols SO2/2 mol FeS2) x 0.95 x (2 mol SO3/2 SO2) x 0.90 x (1 mol H2SO4/1 mol SO3) x 0.90= mols H2SO4.
Convert to grams.