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### Topic: converting a 1% caffeine solution into a mg/g value  (Read 5595 times)

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#### mbckenny

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##### converting a 1% caffeine solution into a mg/g value
« on: March 15, 2012, 03:40:46 PM »
Hi,

I am wondering how to convert a 1% concentration caffeine solution into a g/ml value.

The method I used was as follows;

1ml of caffeine in 100ml, density of caffeine is 1.23 g/ml, therefore 1.23g of caffeine in 100 ml.

But my query is this, do I use 1 ml of caffeine in 100ml or do I assume it is 1 g of caffeine in 100 ml as I would get a different answer if i did that.

Cheers,
Mike

#### Borek

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##### Re: converting a 1% caffeine solution into a mg/g value
« Reply #1 on: March 15, 2012, 04:16:03 PM »
What kind of %? w/w? w/v?
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#### Jasim

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##### Re: converting a 1% caffeine solution into a mg/g value
« Reply #2 on: March 15, 2012, 04:46:52 PM »

But my query is this, do I use 1 ml of caffeine in 100ml or do I assume it is 1 g of caffeine in 100 ml as I would get a different answer if i did that.

% in chemistry is ambiguous. You can have weight % or volume % as pointed out by Borek. They are both different as you have noticed.

#### mbckenny

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##### Re: converting a 1% caffeine solution into a mg/g value
« Reply #3 on: March 15, 2012, 05:04:39 PM »
What kind of %? w/w? w/v?

I believe it was w/w

#### Borek

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##### Re: converting a 1% caffeine solution into a mg/g value
« Reply #4 on: March 15, 2012, 05:14:47 PM »
If it was 1% w/w, then you have 1g in 100g of solution. As this is rather diluted, you may safely assume density of 1g/mL, so you have 1g in 100 mL.

Not that it would be much different in the %w/v case, but it is always better to spell it out.
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