I cant solve this

Question

You need 595 mL of a 60% alcohol solution. On hand, you have a 85% alcohol mixture. How much of the 85% alcohol mixture and pure water will you need to obtain the desired solution?

Answer 1

Hello, thank you for taking the time to post your question!

The key on solving this type of word question is to use the information given in order to set up an equation that represents the situation. For this example that would be

V(alcohol) + V(water) = 595

Then we know that

0.85*V(alcohol) + 0*V(water) = 0.60*595

I would start by solving the second equation algebraically for V(alcohol)

0.85*V(alcohol) = 0.50(495)

V(alcohol) = 0.50(495)/0.85 = 420 mL

Then you can solve the first equation for the corresponding amount of water

420 + V(water) = 595

V(water) = 595 – 420 = 175 mL

What that means is that in order to obtain the desired solution you need 420 mL of the 85% alcohol mixture and 175 mL of pure water.

I hope that helps get you moving in the right direction! Feel free to reach out if you have any additional questions beyond that :)

Answer 2

Amount of alcohol=%*volume of solution

Amount of alcohol in 60% solution=Amount of alcohol in 85%solution

V is volume of 85% solution needed.

0.60*595=0.85*V

(0.60/0.85)*60=V or 420 mL.

Add 175 mL of pure water to 420 mL of 85% alcohol to obtain a 60% alcohol solution.

Answer 3

Let's break this problem into smaller chunks:

You need 595 mL of a 60% alcohol solution.

595 mL of solution and 60% of it should be alcohol. So, we need 595 * 60/100 mL = 357 mL of alcohol and the rest should be water.

On hand, you have a 85% alcohol mixture.

The alcohol can only come from the 85% mixture. So, how much of 85% alcohol do we need to get 357 mL of alcohol:

s85 * 85/100 = 357

s85 = 357 * 100 /85 = 420

The rest of 595 mL solution has to be pure water

w = 595 - 420 = 175