C1V1 = C2V2

Initial inspection of the problem reveals that the concentration units are

different. Either concentration may be converted, the requirement is that both units

must be the same.

Express 0.100 Eq/L Ca(OH)2 in terms of mol/L

0.100 Eq

mol

---------- X ------ = 0.0500 mol/L

L

2 Eq

Using the appropriate expression substitute the values.

C1V1 = C2V2

(6.00 mol/L)(10.0 mL) = (0.0500 mol/L)V2

Solve for the unknown quantity.

6.00 mol/L) (10.0 mL)

V2 = -------------------- = 1200 mL

0.0500 mol/L

When preparing a new standard by mixing two or more standards of known

concentration, the concentration of the new standard times its volume is equal to the

sum of the concentration of the first standard times its volume plus the concentration of

the second standard times its volume and so on depending on the number of standards

being mixed. Keep in mind that the concentration of the new standard will never be

greater than the highest standard nor less than the lowest standard. All concentrations

and volumes must be in the same units respectively. An expression that describes the

relationship between the standards being mixed is as follows:

C1V1 = C2V2 + C3V3 . . . + CnVn

Where:

C1 = Concentration of the new standard

V1 = Volume of the new standard (total volume)

C2, C3, Cn = Concentration of the standards used in preparation

V2, V3, Vn = Volume of the standards used in preparation

MD0837

6-8

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