Question

explain the method of concentration in breaf

Answer 1

The concentration of a solution can be expresses in a number of ways. The important methods are:

Mass/Weight Percentage or Per cent by Mass/Weight :
It is defined as the amount of solute in grams present in 100 grams of the solution.

\small Mass\ Percentage=\frac{Mass\ of\ Solute}{Mass\ of \ Solution}\times 100

\small =\frac{Mass\ of\ Solute}{Mass\ of \ Solute+Mass\ of\ Solvent}\times 100

\small =\frac{Mass\ of\ Solute}{Volume\ of \ Solution+Density\ of\ Solution}\times 100

The ratio mass of solute to the mass of solvent is termed as mass fraction.

Thus, Mass percentage of solute = Mass fraction × 100

10% solution of sugar by mass means that 10 grams of sugar is present in 100 grams of the solution, i.e., 10 grams of sugar has been dissolved in 90 grams of wat

Volume Percentage
It is defined as the volume of solute in mL present in 100 mL solution.
\small Volume\ Percentage=\frac{Volume\ of\ Solute}{Volume \ of \ Solution}\times 100
10% solution of HCl by volume means that 10 mL of liquid HCl is present in 100 mLof the solution.

Mass by Volume Percentage
It is defined as the mass of solute present in 100 mL of solution.
\small \small Mass\ by\ Volume\ Percentage=\frac{Mass\ of\ Solute}{Volume \ of \ Solution}\times 100

A 10% mass by volume solution means that 10 gm solute is present in 100 mL of solution.

Molarity
The molarity of a solution gives the number of gram molecules of the solute present in one litre of the solution.
\small Molarity(M)=\frac{Number\ of\ moles\ of\ solute}{Volume\ of\ Solution\ in\ L}
Thus, if one gram molecule of a solute is present in 1 litre of the solution, the concentration of the solution is said to be one molar.
Units of molarity: mol L-1
Molarity of dilution:
Before dilution After dilution

M1V1 = M2V2

Molarity of mixing:
Let there be three samples of solution (containing same solvent and solute) with their molarity M1, M2, M3 and volumes V1, V2, V3 respectively. These solutions are mixed; molarity of mixed solution may be given as:

M1V1 + M2V2 + M3V3 = MR(V1 + V2 + V3)

Where MR = resultant molarity

V1 + V2 + V3 = resultant molarity

Molarity is dependent on volume; therefore, it depends on temperature.

1 M → Molar solution, i.e., molarity is 1

0.5 M or M/2 → Semimolar

0.1 M or M/10 → Decimolar

0.01 M or M/100 → Centimolar

0.001 M or M/1000 → Millimolar