Chemistry 122 d

Question

Calculate the volume of 0.18 M NaOH needed to react completely with 20.0 mL of 0.45 M H2SO4

H2SO4(aq) + 2NaOH(aq) -> Na2SO4(aq) + 2H-OH(l)

L L

mol/L mol/L

mol mol

(its a chart)

Answer 1

This is a titration problem. You first need to use the balanced the chemical equation:

H2SO4 + 2NaOH → Na2SO4 + 2H2O

Looking at this equation you can see that it will take 2 moles of NaOH to neutralize 1 mole H2SO4. The first thing to do is figure out how many moles of H2SO4 you have. Convert mL to L and multiply the molarity times the volume to get moles. (0.45M)(0.020L) = 0.009 moles H2SO4.

Since we need 2 moles of NaOH to neutralize 1 mole of H2SO4 we will need 0.018 moles NaOH to neutralize 0.009 moles H2SO4.

So now we just need to figure out what volume of 0.18M NaOH is needed to neutralize our H2SO4. We can use dimensional analysis to figure out the volume in liters.

0.018 moles NaOH/(0.18 moles/L NaOH) = 0.100L or 100mL of 0.18M NaOH!

Answer 2

Good morning Chloe! I hope my answer is able to help you with your academic endeavors.

First you always want to check to see if the reaction given to you is balanced. Luckily yours is! So if we are looking to find the maximum amount of NaOH to react with the H₂SO₄, we should first establish how many moles of sulfuric acid we have!

To do that we take the definition of molarity to establish that the total number of moles for sulfuric acid in the reaction is .009 mol.

Moles = Molarity x = 0.45 M x= 0.009 moles of sulfuric acid

Volume(L) 0.02 L

Well, what can we do with this information? Well this is where the balanced reaction comes into play. We can think of the coefficients in the reaction as the ratios needed for a complete reaction. So in our reaction, it will take two moles of NaOH to react with one mole of H₂SO₄. By establishing that we need to react 0.009 moles of sulfuric acid we can calculate from the equation how many moles of NaOH we need with Stoichiometry.

0.009 Moles of Sulfuric Acid X 2 Moles of NaOH = 0.018 moles of NaOH

1 Mole of Sulfuric Acid

Now that we have established the total amount of NaOH moles needed for the reaction, we can once again use the definition of Molarity to calculate how much volume of the 0.18 M NaOH.

0.018 Moles = 0.18 M x = 0.1 L or 100 mL of 0.18 M NaOH

x L