 # Percent (%) concentration calculations vol/vol weight/vol - (Jun/08/2007 )

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What does wt/vol mean?

-smoochiepie79-

SmoochiePie, wt/vol is just a way of expressing weight by volume concentration. Percent concentration can be expressed in other ways too. e.g. %w/w.

For a 10%wt/vol solution you take 10g of solute mass and suspend it in 1000ml. Or 1g mass in 100ml. Same wt/vol ratio. (In fact, you would suspend the 10g in solvent and make up to 1l..which might not be exactly 1000ml depending on the solute's density).

A 5%w/w solution of glucose would have 5g glucose and 95g water (in fact, 95ml since the density of water is 1g/ml).

Then there is %v/v. So a 5% glycerol solution contains 5ml glycerol in 95ml water (total volume is 100ml).

Use w/v when the solutes are solid and vol/vol when they are liquid.

(You also sometimes see ppm, part per million or parts per thousand. Especially so in toxicology, environmental science and chromatography).

Hope that helps without too much headache.

-paraboxa-

QUOTE (paraboxa @ Jun 8 2007, 12:10 PM)
For a 10%wt/vol solution you take 10g of solute mass and suspend it in 1000ml. Or 1g mass in 100ml. Same wt/vol ratio. (In fact, you would suspend the 10g in solvent and make up to 1l..which might not be exactly 1000ml depending on the solute's density).

small correction: 10gm in 1000ml is 1% as is 1gm in 100ml, 10gm in 100ml is 10%.

-mdfenko-

QUOTE
Then there is %v/v. So a 5% glycerol solution contains 5ml glycerol in 95ml water (total volume is 100ml).

why not 5ml in 100ml water?!! -strawberry-

QUOTE (strawberry @ Jun 8 2007, 09:41 PM)
QUOTE
Then there is %v/v. So a 5% glycerol solution contains 5ml glycerol in 95ml water (total volume is 100ml).

why not 5ml in 100ml water?!! Dear, Strawberry

% = (x1/ (x1+x2))*100

where x1 - volume or mass of compound you want to dissolve

x2 - volume or mass of solvent you use to prepare solution with desired concentration

X1+X2 - volume or mass of solution you want yo prepare

-circlepoint-

QUOTE
Then there is %v/v. So a 5% glycerol solution contains 5ml glycerol in 95ml water (total volume is 100ml).

so in this case, we have to add 100ml of water or 95ml!!?

what about a 10% Clorox?!!
usually, i use 10ml of clorox and add to it 100ml of water -strawberry-

QUOTE (strawberry @ Jun 9 2007, 06:37 AM)
QUOTE
Then there is %v/v. So a 5% glycerol solution contains 5ml glycerol in 95ml water (total volume is 100ml).

so in this case, we have to add 100ml of water or 95ml!!?

what about a 10% Clorox?!!
usually, i use 10ml of clorox and add to it 100ml of water Well

If you want to prepare 10%(v\v) you should add 10 ml Clorox+ 90ml H2O
Concerning your calculations you obtain 9% solution ( 10\110)*100,

-circlepoint-

It's in a final volume of 100ml.

So 5% glycerol solution = 5ml glycerol, then bring it up to 100ml with water (this would require 95ml of water).

10% chlorox solution = 10ml chlorox, then bring it up to 100ml (eg with 90ml water).

For solids it's more complicated:
10% SDS = 10g SDS, then bring it up to 100ml, but you don't know how much water that would be so you have to add like 50ml water and let the SDS dissolve and slowly add more water and it's all a big pain because the SDS is foaming up and so you may as well have just used 100ml water to begin with! Except it wouldn't be accurate.

-Zouden-

QUOTE (paraboxa @ Jun 8 2007, 06:10 PM)
SmoochiePie, wt/vol is just a way of expressing weight by volume concentration. Percent concentration can be expressed in other ways too. e.g. %w/w.

For a 10%wt/vol solution you take 10g of solute mass and suspend it in 1000ml. Or 1g mass in 100ml. Same wt/vol ratio. (In fact, you would suspend the 10g in solvent and make up to 1l..which might not be exactly 1000ml depending on the solute's density).

A 5%w/w solution of glucose would have 5g glucose and 95g water (in fact, 95ml since the density of water is 1g/ml).

Then there is %v/v. So a 5% glycerol solution contains 5ml glycerol in 95ml water (total volume is 100ml).

Use w/v when the solutes are solid and vol/vol when they are liquid.

(You also sometimes see ppm, part per million or parts per thousand. Especially so in toxicology, environmental science and chromatography).

Hope that helps without too much headache.

Thank you so much for the explanation, but there was a mistake there as mdfenko states, right? Because I also think if you dissolve 10g in 1000ml that's 1%, not 10%.

-smoochiepie79-

QUOTE
It's in a final volume of 100ml.

So 5% glycerol solution = 5ml glycerol, then bring it up to 100ml with water (this would require 95ml of water).

10% chlorox solution = 10ml chlorox, then bring it up to 100ml (eg with 90ml water).

my god so i made it more concentrated!!!!
thanx for explanation

-strawberry-

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