[ShinyFalcon]

For these problems, I am unable to figure out where to start off. I attempted these problems and could not get the desired numbers.

1) What volume of water must be added to 45.0 mL of a 1.0 M solution of H2SO4 in order to create a 0.33 M H2SO4 solution?

a. 137 mL b. 14.9 mL c. 33.3 mL d. 100 mL (e).    91.4 mL

For this problem, I attempted the (Mdil x Vdil = Mconc x Vconc) formula, but the answer was not correct.

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2) A 10.00-mL sample of 0.254 M H2SO4 is titrated with 0.385 M NaOH. What volume of the NaOH solution, in mL, is required?

a.    6.60     b.    30.3     c.    15.1     d.    10.0     (e).    13.2


I appreciate any hints!

[Borek]

I attempted the (Mdil x Vdil = Mconc x Vconc) formula, but the answer was not correct.

Mass balance, that's the correct formula for the question. Perhpas your answer was total volume, not amount that have to be added? You know, like you forgot subtraction step

A 10.00-mL sample of 0.254 M H2SO4 is titrated with 0.385 M NaOH. What volume of the NaOH solution, in mL, is required?

Start with balanced reaction equation.

[ShinyFalcon]

Ah I see about #1... that's very tricky. Is there a way to find out when to subtract? I guess reading the question is important, but it does get difficult deciphering what's in front of you 

H2SO4 + 2NaOH -> Na2SO4 + 2H2O

If I attempt the formula again, I will get 6.597mL, but I don't know where to plug in the 2.

10mL x 0.254M = 0.385M x ?mL x 0.5

Am I using the right formula? Should I use conversion factors instead? If I were to use conversion factors, would 10mL H2SO4 * (1L/1000mL) * (0.254 mol H2SO4 / 1L) * (2 mol NaOH / 1 mol) * (1L / .385 mol NaOH) work? Oh, I got 13.2mL. Yay!

Thanks for your... assistance!

[Borek]

Method doesn't matter, it is result that counts. Unless you are specifically asked to use this or that method, that is.

Using the same formula here is wrong. It happens to work for the 1:1 stoichiometry, but it gives false idea that it is a correct way of approaching titration problems. It is not. Stick to conversion factors - titration is nothing else but simple stoichiometry.