Many of the chemical solutions have a description in their name such as V/V, W/V and W/W. This blog post is an explanation of what these mean.

Each of these descriptions is a way of expressing the strength of a chemical solution. The strength of a solution can be expressed by Weight, Volume or both. It is easiest to describe each of these separately and illustrate them with an example.

## V/V

V/V means Volume/Volume and is often used when you mix 2 liquids together. For example, a 50% v/v solution would be 50% of one solution and 50% of another – equal amounts of each in terms of Volume. Examples of these include Acetic Acid 50% v/v and Sulphuric Acid 50% v/v.

**You can buy Acetic Acid on Amazon. You can also buy Sulphuric Acid on Amazon in a range of pack sizes and concentrations.**

## W/W

W/W means Weight/Weight. In a solution, it infers the percentage of substances by weight. For example, a Hydrochloric Acid 28% w/w solution means there are 280 grams of Hydrochloric Acid for every Kilogram of the solution (the remainder being water).

## W/V

W/V means Weight/Volume . This is commonly used when a solid is dissolved in a liquid. For example, a 10% w/v solution means 100 grams of one substance is present for every 1L of another. An example of this would be Barium Chloride 10% w/v – in this solution 100 grams of Barium Chloride is present for every 1L of solution.

## V/W

If a solution is V/W it means Volume/Weight. This is the same as the example above but the other way around.

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Thanks for your kind words!

I see this on hydrochloric acid solutions — 20% (v/v). Now, I can understand percent by weight but this is a puzzle to me. Does 20% (v/v) mean 20 parts by volume pure HCl per

100 parts by volume of HCl solution. How do you measure the volume of pure HCl?

Hi Alex,

Your assumption is correct that the product contains 20 parts of HCl per 100 parts of solution, however the concentration of the HCl used is not 100% (that would be a gas) but 36% w/w which is a commonly available industrial grade and generally referred to as concentrated HCl. This still gives off fumes but is a liquid product. So the answer to the question is 200mls of 36% w/w HCl in 1000mls of finished solution, this gives approximately 8.2% w/w solution.

HCl 36% w/w has an s.g. of 1.18 which means 1000mls weighs 1180g. 36% of this is pure HCl, therefore 36% of 1180 = 424.8g or 424.8 grams per litre of HCl. If we take 200mls of 36% w/w HCl we are taking 424.8 x 0.2 grams of pure HCl which equals approx. 85g pure HCl, this 85g is then diluted to 1L.

So in terms of w/w there are 200mls x 1.18 =236g plus approx. 800mls of water (s.g. of 1), giving 1036g in total. 85g of pure HCl in this total weight gives (85/1036) x 100 = 8.2% w/w.

Hope this helps!

It appears that your definition of “v/v” is incorrect. It would work in your example of mixing 2 dilute acids, but when a liquid like alcohol is mixed with water, the volumes are not additive, so 50 mL of alcohol plus 50 mL of water does not equal 50% v/v alcohol, since the total solution volume is less than 100 mL. Please clarify. Thanks.

I need a help! I am working with a polymer (PEI). Commercially it is available in solution and product say- it is 50% w/v in H2O. But, it is so viscous, that, I need to dilute it more. Now the confusion start- If I add x gm into 100 ml, what will be final concentration then?!

Please help!

Please how many grams of PEG 6000 do I need to prepare 10% and 20% of PEG and how can I prepare this!

Hi,

We don’t recommend preparing this product yourself. You should contact a chemical suppliers if you’d like to purchase PEG.

Thanks for your comment.

it really helps me

Dear Sir,

I want to make Pain Killer Oil using methyl salicylate ,camphor,eucalyptus oil,etc.

Can u give me the exact weight wise formulation to make it easy for me to make

Thanks and Regards

Arif Khalak

Dear Arif,

Unfortunately we can’t recommend you mixing a solution of this sort yourself, so cannot give any advice with regards to measurements.

Please contact a chemical supplier who can blend the ingredients safely and accurately for you.

Thanks

I have been thinking of whats the meaning of W/W w/v as it is written on most of the

‘AYURVEDIC PAIN RELIEF OINTMENT’ (I am Indian) which I usese a lot.

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Thank you for this very useful blog!!

Hi!

You really helped me to understand this, it’s so simple.

thank you so much.

Thanks for the information

Please explain as to how I can make a W/V 3% H2O2 to be diluted to a 3% solution

with distilled water .

A very reader-friendly post!

However, I see a correction to be made on w/v:

Instead of “present for every 1L of water,” it should be “present for every 1L of SOLUTION” since you never add a fixed amount of water (due to the errors caused by varying density of different compounds).

Keep posting though, thank you for your help!

Hi Phillip

I’m glad you’re enjoying our posts, and thank you very much for bringing our attention to the error!

Keep reading and we’ll keep posting

how do i prerape hydrochloric acid 1 to 3 V/V

Hi Tsoanelo,

It’s 333ml concentrated 36% HCl diluted to 1000ml with water.

Thanks.

This blog is really butyfully designed that one can use with utmost confidence.. Thanks a a lot

I knew that 1% w/v = 10 grams solute dissolved in 1000/mL. (weight/ volume) or 1 gram dissolved in 100 mL.

So, v/v is volume/volume.

What is difference between 7% (v/v) and 7% (w/v)? is it same volume concentration?

Thanks alot

Hi Adbullah,

7% v/v is 70ml in 1000ml. 7% w/v is 70grams in 1000ml.

No concentration is different due to density of solute.

Thanks.

Thanks for sharing valuable information deserved to visit your page.

Thank you for this useful blog.

Could you please help me? If I pipette an amount with a concentration in w/v and add water, is the new concentration still w/v or is it v/v?

Thanks

Hi Malene, thanks for your comment.

It’s actually both, but the numerical value would be different. This would depend on the density of the material.

Thanks