NEW MATH: THE INVERSE PROPORTION METHOD FOR DILUTIONS AND CONCENTRATIONS (also called percent solution method)

Note: You can solve your problem with either the proportion or formula method, it's all the same but just looks different.

*Inverse Proportion*

C1 Q2

=

C2 Q1

*Inverse Formula*

(Q1)(C1) = (Q2) (C2)

Note: Q1: [First volume quantity given] C1: [First concentration in % given] Q2: [Second volume quantity given] C2: [Second concentration in % given]

(EX) If 500ml of a 15% v/v solution of methyl salicylate in alcohol is diluted to 1500ml, what is the percentage strength v/v?

Lets plug our info in (we are using the Inverse proportion)

(C1)15 % 1500ml (Q2)

(C2) X % = 500ml (Q1) <<<<<<<<<<<< 500ml X 15% / 1500ml = 5% (C2)

Lets plug our info in (we are using the Inverse formula)

(Q1)(C1) = (Q2) (C2)

500ml(Q1) 15% (C1) = 1500ml(Q2) X %(C2)

500ml X 15 / 1500 = 5%

Some alligations problems can be solved with this formula, lets solve with the alligation method first and then we will solve with the inverse formula second.

[Ex] 1. How many cc of Mannitol 10% solution is required to make 500cc of 7.5% Mannitol solution?

10% ___'____________'___7.5% x 500ml / 10% = 375 cc

' 7.5% ' 10%

________________________

0 ' ' 2.5%

2. How many cc of Mannitol 10% solution is required to make 500cc of 7.5% Mannitol solution?

(Q1)(C1) = (Q2) (C2)

500ml (Q1) 7.5%(C1) = X (Q2) 10%(C2)

500 X 7.5 / 10 = 375cc is in a 10% solution