Question

You need a 85% alcohol solution. On hand, you have a 935 mL of a 95% alcohol mixture. How much pure water will you need to add to obtain the desired solution? A) Write an equation using the information as it is given above that can be used to solve this problem. Use x as your veriable to represent the amount of pure water you need to use. Equation: B) You will need mL of pure water to obtain mL of the desired 85% solution.

Answer 1

Since the current solution is 95% alcohol, then the amount of alcohol present is:

`0.95\cdot935=888.25ml`

Let 'x' be the amount of water that we will add to our soulution. Then, the new amount of liquitd would be 935ml + x or 935 + x

We want a solution that is 85% alcohol, so, we have the following equation:

`888.25=0.85(x+935)`

solving for 'x', we get:

`\begin{gathered} 888.25=0.85(x+935) \\ \Rightarrow888.25=0.85x+794.75 \\ \Rightarrow0.85x=888.25-794.75=93.5 \\ \Rightarrow x=(93.5)/(0.85)=110 \\ x=110 \end{gathered}`

Since x = 110, this means that we will have the following:

`935+100=1045ml`

ttherefore, you will need 110ml of pure water to obtain 1045ml of the desired 85% solution