Question 1209852
<font color=black size=3>
I will write the response in English since it's what I'm familiar with. Please use a translator to translate to French.
Je vais écrire la réponse en anglais puisque c'est ce que je connais. Veuillez utiliser un traducteur pour traduire en français.
(translated using Google Translate)


Question:
<font color=blue>I have 100 ml of 99.9% pure DMSO and I need to reduce it to 70%
How many ml of water do I add to get to 70%?</font>


--------------------------------------------------------------------------


x = amount of water, in mL, to add to the solution


You started with 100 mL of 99.9% pure DMSO
0.999*100 = 99.9 mL is pure DMSO while the remaining amount is water.


100+x = amount of solution you end up after adding the x mL of water
The amount of total solution will increase; while the amount of pure DMSO will not increase


(amount of pure DMSO)/(amount of solution) = percentage of DMSO in solution
99.9/(100+x) = 70%
99.9/(100+x) = 0.70
99.9 = 0.70(100+x)
99.9 = 70+0.70x
0.70x = 99.9-70
0.70x = 29.9
x = 29.9/0.70
x = <font color=red>42.714285714286 approximately</font>



Answer: You must add <font color=red>approximately 42.714 mL</font> of water to the solution.
Round the approximate answer however your teacher instructs.
</font>