Final answer:
To prepare 100 ml of 60% ethyl alcohol using a 70% solution, 85.71 ml of the 70% solution should be mixed with 14.29 ml of water, based on the dilution formula C1V1 = C2V2.
Step-by-step explanation:
The subject of this question is calculations using volume percentage in Chemistry, specifically in the context of preparing a solution with a desired concentration. To prepare 100 ml of a 60% ethyl alcohol solution from a 70% solution, we can use the simple dilution formula: C1V1 = C2V2, where C1 and V1 are the concentration and volume of the initial solution, and C2 and V2 are the concentration and volume of the final solution.
Let's assume we need V1 ml of the 70% alcohol solution. Since the final volume (V2) is 100 ml and the final concentration (C2) is 60%, our equation looks like this: 70% * V1 = 60% * 100 ml. Solving for V1 gives us V1 = (60% * 100 ml) / 70%, which calculates to approximately 85.71 ml. This is the amount of the 70% ethyl alcohol we need.
To find out how much water to add, we subtract the volume of ethyl alcohol from the total desired volume: 100 ml - 85.71 ml, which yields approximately 14.29 ml of water. Therefore, we need to mix approximately 85.71 ml of the 70% ethyl alcohol with approximately 14.29 ml of water to get 100 ml of a 60% ethyl alcohol solution.