Help me out with a maths calculation

[Galena]

Maths are not my strong point and I could do with some help.

I want to make a 33% solution of Calcium Chloride from my flakes.
The flakes have a 77% purity.
Therefore to make 100mls of 33% solution, first I need the weight required which I have as:
33/.77 = 43g

So I dissolve 43g Calcium Chloride with distilled water to make 100mls.

That's the easy bit.

So if I wish to add the liquid equivalent of 1 gram of Calcium Chloride, how much of the solution do I use?

 

[starseeker]

i could be wrong, but i made it 3.3 ml = approx 1g of calcium chloride

 

[Agentgonzo]

Your solution has 33g of calcium chloride in it.

Note that just because you started out with 100ml of water doesn't necessarily mean you end up with 100ml of solution - it may be more than 100ml by a little bit.

You want 1g of calcium chloride. So take your total volume of solution and divide by 33. If your solution is 100ml then 100/33 = 3.3ml as starseeker says. If your solution is a bit more than 100ml, then you'll end up with a bit more than 3.3ml.

 

[Galena]

i could be wrong, but i made it 3.3 ml = approx 1g of calcium chloride

Thank you :)

Note that just because you started out with 100ml of water doesn't necessarily mean you end up with 100ml of solution - it may be more than 100ml by a little bit.

Actually I added the CaCl2 to a container and then topped up to 100mls rather than adding 100mls

 

[Galena]

You want 1g of calcium chloride. So take your total volume of solution and divide by 33. If your solution is 100ml then 100/33 = 3.3ml as starseeker says. If your solution is a bit more than 100ml, then you'll end up with a bit more than 3.3ml.

But if I have 200mls of 33% solution then the math doesn't work? 200/33 = 6.06, yet the concentration is the same.