Question 1200052
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The response from the other tutor shows a standard formal algebraic solution -- which you should understand, if you are a student learning how to solve problems using algebra.<br>
If the speed of obtaining the answer is important and any method can be used (as in a timed math competition), here is an informal solution method that is much faster and easier than the formal algebraic method.<br>
The 50% target concentration is 1/3 of the way from the 25% concentration of the original acid solution to the 100% concentration of the acid that is added. (25 to 50 is a difference of 25; 25 to 100 is a difference of 75; 25/75 = 1/3.)<br>
That means 1/3 of the mixture should be what is being added.<br>
So 2/3 of the final mixture is the original 25% acid solution; and that means the amount of 100% acid being added is half the amount of the original 25% acid solution.<br>
ANSWER: 1/2 of 500 mL = 250 mL<br>