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# Help with simple equation Watch

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1. ......
2. Im wondering if someone can help me here. I hate these kind of questions...Just not good at them.

I have 80mL of H2SO4 98%w/w and I need O.1M in 80 mL.

So far I have worked out that C1V1 = V2C2 is required.

First of all I worked out the density m/V which equals 1.22 g/,L (Or does it, or do I even need it).

98% = 98g in 100g solution. Moles = mass/mr = 98/98.079 = 1M

Im wondering if someone can help me here. I hate these kind of questions...Just not good at them.

I have 80mL of H2SO4 98%w/w and I need O.1M in 80 mL.

So far I have worked out that C1V1 = V2C2 is required.

First of all I worked out the density m/V which equals 1.22 g/,L (Or does it, or do I even need it).

98% = 98g in 100g solution. Moles = mass/mr = 98/98.079 = 1M

Calculate how many moles of acid there are in the original liquid.

Now calculate how many moles there would be in 80 ml of 0.1 mol dm-3 solution ...

Can you see where to go from here?
4. (Original post by charco)
Calculate how many moles of acid there are in the original liquid.

Now calculate how many moles there would be in 80 ml of 0.1 mol dm-3 solution ...

Can you see where to go from here?
Am I right or wrong so far?

Do you mean work out the moles with the formula moles = mass/mr then multiply it by 0.08?

I am laughably bad at these
Am I right or wrong so far?

Do you mean work out the moles with the formula moles = mass/mr then multiply it by 0.08?

I am laughably bad at these
Your target is a solution with volume 80 ml and a concentration of 0.1 mol dm-3

This contains 0.08 x 0.1 = 0.008 mol of solute.

Your original solution is given in w/w (is this correct, not w/v) ?

If it's w/w then every 100g contains 98g sulfuric acid and 2 grams of water. Without the density of the mixture you cannot find the mass.

How did you work out the density?
6. (Original post by charco)
Your target is a solution with volume 80 ml and a concentration of 0.1 mol dm-3

This contains 0.08 x 0.1 = 0.008 mol of solute.

Your original solution is given in w/w (is this correct, not w/v) ?

If it's w/w then every 100g contains 98g sulfuric acid and 2 grams of water. Without the density of the mixture you cannot find the mass.

How did you work out the density?
P=m/v

The question was definitely written as w/w. But I'm starting to think he's wrong and w/v makes more sense
P=m/v

The question was definitely written as w/w. But I'm starting to think he's wrong and w/v makes more sense
How can you use p = m/V if you don't know 'm'?
8. OH Ffs.

I used mr mass.

I truly am an idiot. I hate dilutions
9. Do I have to determine m first by doing mr mr x moles? H2SO4 mr x .0008?
Do I have to determine m first by doing mr mr x moles? H2SO4 mr x .0008?
I don't think that you can do the question with w/w values ...

... you don't know the mass of the 80ml of stock solution and there is no way to find it without the density.
11. I googled the density and it is1.8 shall I use that ?
12. (Original post by charco)
I don't think that you can do the question with w/w values ...

... you don't know the mass of the 80ml of stock solution and there is no way to find it without the density.
You think I should do it w/v?
You think I should do it w/v?

14. (Original post by charco)

Say it is w/w...And I googled the density is this it?

Would this be it?

So if in water... in water. In 100g, I have 98g of H2SO4.

H2SO4 has MM~98g/mol, so thats about 1mol/100g. Density of water is about 1g/mL, and at room temperature, H2SO4 is a liquid with density 1.84g/mL.

So 98/1.84+2/1=55.3mL, so you I have a liquid with concentration 1mol/55.3mL. The rest is just a dilution to 80mls?

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Updated: October 4, 2016
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