Erasmus chemistry problem tomorrow! I 30. Urgent?

Hi I am on erasmus and I have two problems which I have no very clear and I have due tomorrow.

This is the first.

1 º. You are Given to 98%w / w solution of sulfuric acid and you Are Asked to make a 0.2 N solution to a volume of 1 liter. Describe in detail all the steps That lead to this Taking Into account all necessary safety precaution. (Atomic weights: H = 1, O = 16, S = 32)
1 º. They give you a 98%w / w sulfuric acid solution and asked to make a 0.2 N solution to a volume of 1 liter. Describe in detail all the steps that lead to this, taking into account all necessary safety precautions

And this is the second

2 º. You are Given a pure solution of ethanol (CH3CH2OH) and a pure solution of water and Asked to make a 25%(v / v) solution of ethanol and a 3M solution of ethanol. Describe in detail all the steps That lead to this Taking Into account all necessary safety precaution (pm: H = 1, O = 16, C = 12)
2 º. It gives a solution of pure ethanol (CH3CH2OH) and a pure water solution and asked to make a 25%(v / v) ethanol and an ethanol solution of 3M. Describe in detail all the steps that lead to this, taking into account all necessary safety precautions (atomic mass: H = 1, O = 16, C = 12)

Thanks before hand. As you have seen I put the translation in Spanish.

Answer

* 98%p / p mean = 98 g of ac. 100 g sulfuric solution. This is the starting point. Then you ask from this solution, get another concentration 0.2 N. -
One solution is that q 1 N 1 eq is dissolved in one liter of solution. In the case of sulfur, Eq 1 is M (molecular weight) / 2 (nr of protons) .-
Let M = 98 g / mol, then Eq = (98 g / mol) / (2 / mol) = 49 gr. Q is the mass of sulfuric ac though for a 1 N solution, but we are interested in a 0.2 N, therefore, rule of 3 simple, to make 1 liter of solution 0.2 N of AC. SULFURIC, WE GR Q dissolving 9.8 AC. SULFURIC AND TAKE A 1 LITER .-
But we start dce a solution 98%w / w, so, the problem is in knowing that solution q contine volume of 9.8 g / ac. sulfuric .-
We know by definition that:
Ac 98 grs. ----------------- 100 g sulfuric solution
9.8 g of ac. ----------------- sulfuric x = 10 g

So, weight 10 grams of this solution, or better yet, if you know the density of it, take the equivalent volume of solution of the 10 g and a volumetric flask of 1000 cm ^ 3 volume and took him there I have my 0.2 N. solution -
The other problem is resolved in a similar manner .-
HITS

Category: Chemistry
Region: Argentina
Date: November 19, 2009
Source: Original question and all answers - Powered by Yahoo! Answers
Question by Alex A, answer by Mauricio D.
Translated from Spanish by Google Language Tools