how many grams of H2SO4 must be weighed out? Assume a molar mass of 98.1g/mol and give the answer to 2 significant figures, with units, such as 12g.

Question

In order to make 0.100L of a 6.0M solution of H2SO4, how many grams of H2SO4 must be weighed out? Assume a molar mass of 98.1g/mol and give the answer to 2 significant figures, with units, such as 12g.

Answer 1

6.0 mole/L x 0.100 L = 0.60 moles required

0.60 moles H₂SO₄ x 98.1 g/mole = 58.9 grams of H₂SO₄ required = 59 g to 2 sig. figs.

Now comes the problem.  Unless the H₂SO₄ is 100%, you cannot simply weigh out 59 grams.  So, without knowing the % H₂SO₄, we can't really answer the question adequately.  If we assume it is 98% (which is common), then you have...

58.9 g/0.98 = 60 grams needed.

Answer 2

0.100L of a 6.0M solution of H2SO4 = .100 L x 6.0 mole/L = .6 mole

 

.6 mole H2SO4 x 98.1 g H2SO4/1 mole H2SO4 = 58.86 = 59 g H2SO4