SOLUTION: I need to mix a cleaning solution that would spray out of a bottle and contain 70% rubbing alcohol to clean lab surfaces. To save cost, it makes sense to add water to some amount o

Algebra ->  Conversion and Units of Measurement -> SOLUTION: I need to mix a cleaning solution that would spray out of a bottle and contain 70% rubbing alcohol to clean lab surfaces. To save cost, it makes sense to add water to some amount o      Log On


   



Question 980554: I need to mix a cleaning solution that would spray out of a bottle and contain 70% rubbing alcohol to clean lab surfaces. To save cost, it makes sense to add water to some amount of alcohol yet maintain the 70% level. Average spray bottles likely hold about 25 fl ounces or what about 800 ml? What should my solution look like? Thank you. Leann
Found 2 solutions by ankor@dixie-net.com, josgarithmetic:
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
add water to some amount of alcohol yet maintain the 70% level.
Average spray bottles likely hold about 25 fl ounces or what about 800 ml?
What should my solution look like?
:
let x = amt of alcohol to be removed and amt of water to be added
Lets use an amt of alcohol to be 25 oz
25 - x = .7(25)
25 - x = 17.5
-x = 17.5 - 25
-x = -7.5
x = 7.5 oz of alcohol removed and 7.5 oz of water added maintaining a 25 oz bottle

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
What are your materials? If you add some amount of water to 70% alcohol, then you will obtain a concentration of alcohol LESS THAN 70%.

If you are starting with 100% alcohol and want to add some water to prepare 25 fluid ounces of 70% alcohol, then ...

v, volume of the "pure" alcohol of 100%;
25-v, volume of the water to add;

%28100%2Av%2B0%2A%2825-v%29%29%2F25=70

%28100v%29%2F25=70
Find v, and then find 25-v.