Add 40 ml of ice cream to 60 ml of milk. assume a final volume of 100 ml. what dilution of ice cream is this?

Question

Add 40 ml of ice cream to 60 ml of milk. assume a final volume of 100 ml. what dilution of ice cream is this?

Answer 1

dilution = 100/40 = 2.5

2.5-fold dilution

Answer 2

you're not given an "initial concentration" of ice cream in this question.. so lets assume its "X".. or lets use 1mg/ml just to see how it changes in the final conditions. using MVi = MVf will get you this answer.. but always think about these rationally too. A 1/2 dilution means equal parts of both.. so you're adding more milk so your dilution will be greater than 1/2.. or "greater than a 2 fold dilution"

MV = MV. (1)(40) = (X)(100), with X = 1/2.5.

so look at this now.. assuming a starting concentration of 1 and a final concentration of 1/2.5.. a "2.5 fold" dilution must have taken place. This makes sense according to our rational estimate.

the key to this question was assuming any initial concentration and just "seeing" how it changes, designating x as the final concentration and solving for it using MV= MV. If we arbitrarily set our initial milk concentration at 10mg/ml.. then our final concentration would have been "4mg/ml", if you solve for x. Again we'd be able to tell that a "2.5fold" dilution must have taken place to get you that new concentration.

hope this helps.. they're fun to think about.