stoichiometry?

Question

I'm having a problem remembering how to do this problem. can someone tell me the steps and i can actually do it? thanks!

How many moles of hydrogen are in 0.684 grams of sulfuric acid?

Answer 1

The best way to answer a question like this is write the equation linearly. Begin with what you have, written on the extreme left of the line, and write what you want on the extreme write:

0.684g H2SO4 = ___mol H

There are a few things you know about the dimensional relationships between grams, mols, Hydrogen and Sulfuric acid. It is good to jot them down below your line set-up.

0.684g H2SO4 = ___mol H
molecular weight H2SO4 = (you do the math)g H2SO4
mol ratio of hydrogen to sulfuric acid = (2 mol H)/(1 mol H2SO4)

Now that you have all the information you need, use dimensional analysis to string your equation along, making sure that you are placing grams and moles in the correct spot in the numerator/denominator, so as to cancel out:

0.684g H2SO4 x (1 mol H2SO4)/(mol weight H2SO4) x (2 mol H)/(1mol H2SO4) = ___ mol Hydrogen

grams H2SO4 cancel out, mol H2SO4 cancel out, and you are left with mol hydrogen as your unit. Up to you to do the calculation.

If you need any further help, I'm here for you!

Answer 2

You take 0.684 g of Sulfuric Acid, multiply it by the factor (1 mol of Sulfuric Acid/98.0778g of Sulfuric Acid). Then you are left with the number of moles of Sulfuric Acid. Next multiply that by the factor (2 mol Hydrogen/1 mol Sulfuric Acid). And you have your answer: 0.0139 moles of Hydrogen.

Theory: If x gs of H2SO4 (x) 1 mol H2SO4/98.0778g H2SO4 (x) 2 mol H/1 mol H2SO4 = 2x/98.0778 mol H

Answer 3

The problem is solved using the factor label method to cancel units, and the following assumptions:
Avogadros Number: 6.02E23 (=6.02 x 10^23, or 6.02 times ten to the 23d)
Molecular weight Sulfuric Acid (H2SO4) = 98.08 g/mol
There are 2 atoms Hydrogen for every molecule of Sulfuric Acid
The problem states you have 0.684 grams of sulfuric acid.
The problem uses 3 sig figs, so the answer should have 3 sig figs (use full precision for intermediate calcs)

Solution:

0.684 g / 98.08 g/mol = 6.97E-03 moles H2SO4;
6.97E-03 moles H2SO4 x 6.02E23 molecules/mole = 4.19E21 molecules H2SO4;
4.19E21 molecules H2SO4 x (2 atoms H/molecule H2SO4) = 8.40E21 atoms H;
8.40E21 atoms H / (6.02E23 atoms/mole) = 0.139 moles H

Your answer is therefore 0.139 moles of Hydrogen!

Answer 4

First you determine how many moles of sulfuric acid you have by dividing the gram weight by moles/gram (molar weight of sulfuric acid in grams-by definition, one mole of a substance is the molecular weight in grams, i.e, 1 mole of carbon-12 is 12 g.) . Then you determine the number of H moles in H2SO4 and see there are 2 H's per molecule of H2SO4, thus there are twice as many moles of H as there are moles of H2SO4. (2 H's per H2SO4 so multiply moles of H2SO4 by 2 and you have moles of H, more correctly, H+).

Answer 5

easiest way to do this particular problem, which is really conversion rather than the balancing of an equation is to form a product in which you cross out like terms, that way you can check your answer

(2 moles of h++)/(1mole H2SO4)* (1mole H2SO4/MWtH2S04 g) * 0.684 g H2SO4 = X moles of hydrogen ion

X moles of h+ * (1/2 mole H2 gas/1 mole H2 gas)= y mole H2 gas

Answer 6

You need to calculate the percent composition of hydrogen in sulfuric acid.

sulfuric acid H2SO4

Molar mass of H2SO4
H: 1.0 g/mole x 2 atoms = 2.0 grams/mole
S: 32.1 g/mole x 1 atom = 32.1 grams/mole
O: 16.0 g/mole x 4 atoms = 64.0 grams/mole
add to get molar mass = 98.1 grams/mole

(2.0/98.1)x100 = percent composition of hydrogen in sulfuric acid
.02039 x 100 = 2.04% hydrogen

find 2.04% of your original amount of sulfuric acid to find the mass that is due to hydrogen

0.684x.0204=.0139 grams of hydrogen

Since there is 1.0 g of hydrogen in every mole of hydrogen (atomic weight on periodic table is mass of an element present in a mole of that element), mole to mass is a 1:1 ratio. For other elements, you would have to divide the number of grams present in the sample by the number of grams present in the element you are interested in (its atomic weight).

Therefore, there are 0.139 moles of hydrogen in your sample.