Question 1189755: How much water should be added to 30 mL of 19% alcohol solution to reduce the concentration to 15%?
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39618)   (Show Source):
You can put this solution on YOUR website! Before adding the water,
Adding x mL water to reduce concentration,
The volume changes but not the pure amount of alcohol.
Solve this for x.
Answer by ikleyn(52797)  (Show Source):
You can put this solution on YOUR website! .
How much water should be added to 30 mL of 19% alcohol solution to reduce the concentration to 15%?
~~~~~~~~~~~~~~~~
For dilution problems like this one, there is another way to solve, quite simple . . .
If V is the new volume of the solution after adding water, then, OBVIOUSLY, this equation is held
0.19*30 = 0.15*V,
saying that amount of the pure alcohol does not change. It gives for this new volume
V =  = 38 milliliters.
The difference 38 mL - 30 mL = 8 mL is the volume of water to add. ANSWER
Solved.
-----------------
It is a standard and typical mixture problem.
For introductory lessons covering various types of mixture word problems see
- Mixture problems
- More Mixture problems
- Solving typical word problems on mixtures for solutions
- Typical word problems on mixtures from the archive
in this site.
You will find there ALL TYPICAL mixture problems with different methods of solutions,
explained at different levels of detalization, from very detailed to very short.
Read them and become an expert in solution mixture word problems.
Specially for DILUTING problems, see another lesson
- Special type mixture problems on DILUTION adding water
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook in the section "Word problems" under the topic "Mixture problems".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.
|
|
|
