[T]

The question was:

What is the density of the sulfuric acid solution (g/mL) if its percent w/w concentration is 60.16% and w/v percent concentration is 90.24%?

I have started in a new topic because I am thinking that it might lead to something other than the problem.

My first question is what does w/v percent concentration is? I tried googling it and it said for this case it would be the
sulfuric acid volume/ solution volume.

But if it is so then the working out showed on the original thread would be wrong.

Thanks

Mod edit: For convenience, here is a link to Problem of the week 27/05/2013. Dan.

[mjc123]

w/v means weight/volume, so the answer you found is wrong.
60.16% w/w means 60.16 g sulfuric acid per 100 g solution.
90.24% w/v means 90.24 g sulfuric acid per 100 mL solution.

[T]

I see, then the answers add up now. One more thing:

For w/w the units of both w needs to be the same right?

For w/v would the units of the w always be (g) and v always be (mL), or could it be different.

Thank you very much.

[sjb]

I see, then the answers add up now. One more thing:

For w/w the units of both w needs to be the same right?

For w/v would the units of the w always be (g) and v always be (mL), or could it be different.

Thank you very much.

In my experience, no - so you could have ounces per gallon (UK or US). or a mixture of imperial and metric in the same measurement. So you need to be careful when preparing things this way.

[Dan]

For w/w the units of both w needs to be the same right?

Yes, it should be unitless.

See: https://en.wikipedia.org/wiki/Mass_fraction_%28chemistry%29

(% w/w = 100 x mass fraction)

For w/v would the units of the w always be (g) and v always be (mL), or could it be different.

It usually means g/mL, because the density of water is 1 g/mL so it is intuitively more like a dimensionless quantity when expressed in g/mL. However, % m/v concentration is not very well defined (or it might be more accurate to say it is commonly misused). It's a bit of a minefield (I think it should be phased out myself). See: https://en.wikipedia.org/wiki/Mass_concentration_(chemistry)#Units

Edit: Link fixed

[T]

All right thank you very much Dan.

so it is intuitively more like a dimensionless quantity when expressed in g/mL.

What does dimensionless quantity mean?

[Arkcon]

All right thank you very much Dan.

so it is intuitively more like a dimensionless quantity when expressed in g/mL.

What does dimensionless quantity mean?

Write it out.  If something weighs 5 grams, and 5 mls of water weighs 5g, what does 5g/5ml equal?  Include the units, and when you cancel 5/5, remember, you can cancel the units as well.

[billnotgatez]

https://en.wikipedia.org/wiki/Mass_fraction_%28chemistry%29
Mass fraction (chemistry)

The link given by @Dan had the last parenthesis missing due to the way parenthesis are handled in links
I post the link again with the % notation for clarity.

[T]

Thanks guys.

[T]

Arkcon, another question

Include the units, and when you cancel 5/5, remember, you can cancel the units as well.

Do you mean for the 5g/5mL situation or another? Because for the 5g/5mL, you can cancel the 5 but not the units.

[Arkcon]

Can't you?  Ii 1 ml of water weighs 1 g, aren't the units also unity and cancel-able?  Can't you also cancel 1000 ml/1 L, or 40 g of NaOH/1 mol NaOH?  These are other proportions you will have to get used to performing.

[Borek]

Can't you?  Ii 1 ml of water weighs 1 g, aren't the units also unity and cancel-able?  Can't you also cancel 1000 ml/1 L, or 40 g of NaOH/1 mol NaOH?  These are other proportions you will have to get used to performing.

I think this is misleading. 5 g/5 mL is 1 g/mL - units don't cancel out, instead they produce g/mL which is a density unit. Also, 40 g per 1 mole for NaOH doesn't cancel out - it yields 40 g/mol, where g/mol is a unit of molar mass. Units cancel out when they are identical, so for example 20 g/1000 g yields dimensionless 0.02.

Whole dimensional analysis  (https://en.wikipedia.org/wiki/Dimensional_analysis) is based on these concepts.