Final answer:
To prepare a 20% alcohol solution using a 90% alcohol and a 10% alcohol, you need to calculate the amount of each alcohol required using a mathematical equation.
Step-by-step explanation:
To prepare 1L of a 20% alcohol solution using a 90% alcohol and a 10% alcohol, we need to calculate the amount of each alcohol required. Let's assume we need x mL of the 90% alcohol and y mL of the 10% alcohol.
The concentration of alcohol in the 90% alcohol is 90% or 0.9, and the concentration of alcohol in the 10% alcohol is 10% or 0.1.
So, the total amount of alcohol in the solution would be 0.9x + 0.1y.
For a 20% alcohol solution, the total amount of alcohol is 0.2L or 200 mL.
Setting up the equation: 0.9x + 0.1y = 200 mL
Solve this equation to find the values of x and y, which represent the amounts of the 90% alcohol and the 10% alcohol needed to prepare the desired solution.