Question

What mass of potassium hydroxide is required to react completely with 2.70 grams of sulfuric acid to produce potassium sulfate and water?

Answer 1

1) first, write the balanced equation:

2KOH + H₂SO₄ ---> 2H₂O + K₂SO₄

2) convert grams of sulfuric acid to mole using it's molar mass. 

molar mass H₂SO₄= (2 x 1.01) + 32.0 + (4 x 16.0)= 98.0 g/mol

2.70 grams (1 mol/ 98.0 grams)= 0.0276 moles

3) use the mole to mole ratio from the balanced equation to change the moles of sulfuric acid to moles of potassium, hydroxide (KOH).

ration--->2 mol KOH = 1 mol H₂SO₄

0.0276 mol H₂SO4 (2 mol KOH/ 1 mol H₂SO₄)= 0.0551 mol KOH

4) convert moles to grams using the molar mass of KOH

molar mass of KOH= 39.1 + 16.0 + 1.01= 56.1 g/mol

0.0551 mol (56.1 grams/ 1 mol)= 3.09 grams