SOLUTION: Hi i had 2 questions. My first question is this. How many gallons of pure alcohol should be mixed with 20 gal of a 15% alcohol solution to obtain a mixture that is 25% alcohol? I
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Question 257068: Hi i had 2 questions. My first question is this. How many gallons of pure alcohol should be mixed with 20 gal of a 15% alcohol solution to obtain a mixture that is 25% alcohol? I have done this problem several times and i get as far as .15x + 3 = .25x + 5 but i keep getting a negative answer. Could you please show me how to solve this correctly. My other question is this Marin Caswell needs 10% hydrocholoric acid for a chemistry experiment. How much 5% acid should mix with 60 mL of 20% acid to get a 10% solution? I really want to know how to solve these and set them up so i can do them on the test. Thank you
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
How many gallons of pure alcohol should be mixed with 20 gal of a 15% alcohol solution to obtain a mixture that is 25% alcohol?
;
Let x = amt of pure alcohol required
:
A per cent equation
.15(20) + 1x = .25(x+20)
3 + 1x = .25x + 5
1x - .25x = 5 - 3
.75x = 2
x =
:
x = 2 gal of pure alcohol required
:
:
Marin Caswell needs 10% hydrocholoric acid for a chemistry experiment.
How much 5% acid should mix with 60 mL of 20% acid to get a 10% solution?
:
Let x = amt of 5% mixture required
:
.05x + .20(60) = .10(x+60)
.05x + 12 = .10x + 6
12 - 6 = .10x - .05x
6 = .05x
x =
x = 120 ml of 5% stuff
:
Prove this
.05(120) + .20(60) = .10(120 + 60)
6 + 12 = .10(180)
18 = 18
:
:
You can prove the 1st one, like we did this one.
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