2) Sulfuric acid reacts with copper to produce cupric sulfate and hydrogen gas. If you hae a solution of sulfuric acid that is 40 percent hydrogen sulfate by weight , how many grams of copper do you need to react with 20 grams of sulfuric acid?

First of all, thank you for taking the time to post your question at the Ask Me Help Desk!

Let me say to begin here that I am interpreting this problem in two different ways. I shall provide two scenarios and let you pick the one that best fits what you are being asked to do in class. I will provide the steps for you on the stoichiometry piece and let you do the math.

SCENARIO I

If we assume that the 20 g of sulfuric acid in the problem represents the 40% hydrogen sulfate we must first determine the mass of the solution.

We can do this by using the following formula...

% mass = mass of solute/(mass of solute + mass of solvent) * 100

Substitute your values

40% = 20g/(20g + X) * 100

0.4(X+20) = 20

0.4X + 8 = 20

0.4X = 12

X = 30

Plugging 30 into our original equation tells us that we woud have 50 grams of solution in the reaction. This then becomes a mass-mass stoichiometry problem for which we can use the following steps...

1. Make sure you have balanced equation

2. Determine the needed and the given

3. Convert your 50 g of H2SO4 to moles

4. Multiply by the molar ratio of copper to sulfuric acid from balanced equation

5. Convert moles of copper to grams of copper


SCENARIO II

Since you indicated 20 grams of sulfuric acid in the problem (which would indicate that it was already in solution), we can just use that value in our stoichiometry calculations.

Simply replace the 50 grams from step 3 above with 20 grams and solve.

I would like to know what you got for answers after you work these out.

I hope this was helpful.
Good luck!