Question

Exercise 5-3: HOMEWORK Math Exerdses in Alligation Name A. Objective: To reinforce the ability to apply alligation in various situations ning and you. 70% rather you end up cent is nee Problem 1: Scenario: You ordered a gallon of Isopropyl Alcohol70% (IPA), but there was a mistake in shipping and you received IPA 90%. The distributor gives you the option to Keep it at the same price as the 70% rather than paving return shipping and a re-stocking fee. It's a win-win situation for both parties. You and up with more alcohol, because this will last longer than the 70% stock, and anytime a lesser percent is needed, it will be simple to dilute. Using the 90%You have a prescription that requires 40mL of 70% IPA. How much IPA 90% and purified water are needed to make the 40mL? (If the required number of parts are fractions, it is acceptable to round to the nearest whole number.) Calculations: mLs IPA 90% _mls Purified Water

Answer 1

Using the law of dilution we have,

CV = CV

Here, C_u is concentration of undiluted solution which is 90% (or 0.9)

C_d concentration of diluted solution which is 70% (or 0.7)

V_d is volume of diluted solution which is 40 mL.

V_u is volume of undiluted solution which we need to find out. Thus, we have,

0.9*V = 0.7 * 40mL 28mL Vu= -= 31.11ml 0.9

Thus, you need to take 31.11 mL of 90% solution. The remaining amount that is 40 mL - 31.11 mL = 8.89 mL will be water.

31.11 mL 90% IPA and 8.89 mL purified water.