Mixing chemical question

[mark]

When something says mix up a 10% solution of X how do I do that? Ratios I can handle. % solutions have me completely bamboozled. I have been looking on the net and my head is starting to hurt.

I need a layman's explanation.

[Ian Grant]

10% is 100gm per litre, dead easy.

Ian

[Robert Hall]

10% is 100gm per litre, dead easy.

Ian

But be careful that some chems take up more room in the liter than others. Starting with 1 liter then adding chems does not a correct percentage make.

And you don't want to add water to some chems such as acid as it may spit or explode acid everywhere.

Start with a portion of the water, maybe 75%, then add the chems, then top it off to a liter.

Cheers,

[Kami-the-Trout]

10% is 100gm per litre, dead easy.

Ian

Or 10 grams per 100 ml, or one gram per 10 ml . . . it's all 10 per cent.

[mark]

Now why couldn't those sites say that. Damn. Thanks.

[olleorama]

Percent can be either by volume or by weight. Be careful on what properties are used.

[Ian Grant]

Percent can be either by volume or by weight. Be careful on what properties are used.

Or they can be a mix of both

Ian

[Photo Engineer]

If you add 10 grams of Sodium Chloride to 80 ml of water and then dilute to 100 ml, you have a 10% wt/vol solution.

If you add 10 ml of Alcohol to 80 ml of water and then dilute to 100 ml with water, you have a 10% vol/vol solution.

If you add 10 grams of alcohol to 80 grams of water and then dilute to 100 grams, you have a 10% wt/wt solution.

If you add 10 ml of Alcohol to 80 grams of water and then dilute to 100 grams you have a 10% vol/wt solutoin.

Note that you can add water to make 100 grams or 100 ml. This gives a different solution in each case.

Each is different. Each will be almost the same but not quite. If you use the same method every time, it will at least be consistent.

I use wt/wt for viscous materials or in the dark as weight is easier to manage in these cases. I use wt / vol for solid-liquid and I use vol/vol for two liquids which are non viscous and when I am not dark as combinations of this sort are pretty much standard.

PE

[mark]

I need to make a 9% solution of silver nitrate. Since it is a powder do I do wt/vol? Head ache is back.

[Photo Engineer]

Do wt/vol.

PE