Ways of expressing concentrations 1
Table of Contents
Ways of expressing concentrations 1 of a solution:
A solution can be expressed qualitatively and quantitatively. In both ways of expression, the emphasis is laid on the substance which is present in lesser quantity in a binary solution.
In a binary solution, the substance which is present in a lesser quantity has termed a solute, and a substance that is present in a larger quantity or into which solute is added is regarded as a solvent.
In chemistry binary solution is usually expressed as solute and solvent for example when sodium chloride is added to water to form a solution then sodium chloride is regarded as solute while water is regarded as a solvent and the mixture formed a solution.
Qualitatively Expression:
The solution of sodium chloride can be expressed as dilute sodium chloride solution, dilute means a solution in which the quantity of solute is less. Secondly, concentrated sodium chloride solution (brine), which means a large quantity of solute is present in the solution
Quantitatively Expression
Quantitatively solutions in chemistry is expressed as
Percentage mass of solute
The first method in ways of expressing concentrations 1 is the percentage mass of solute or %mass of solute is the mass of solute with respect to the total mass of the solution. It is expressed as (w/w) or by weight.
Both mass of the solute and the mass of the solution is taken in same units either in grams or kgs
Mathematical expression
Question:
The Aqueous Hydrochloric acid solution is 20% (w/w). How many grams of Hcl is present in the sample?
Answer:
The solution is an aqueous hydrochloric acid solution (i.e. HCl + Water)
Suppose the weight of the solution is 100 gm
substituting in above formula we get
percentage volume of solute
The second method in ways of expressing concentrations 1 is the percentage volume of solute or % volume of solute is the volume of solute with respect to the total volume of the solution. It is expressed as (v/v) or by volume.
Both volumes of the solute and the volume of the solution are taken in the same units either in mL or Lt.
Mathematical expression
Beer contains 10% (v/v) of ethyl alcohol. Calculate volume of ethyl alcohol in beer?
Answer:
Beer is an aqueous solution of ethyl alcohol and water.
Let volume of beer is 100 mL
Substituting in above formula we get
percentage strength of solute
The third method in ways of expressing concentrations 1 is the percentage strength of solute or % strength of solute is the mass of solute with respect to the total volume of the solution. It is expressed as (w/v) or by strength.
In this mass of the solute and the volume of the solution are taken in the same dimensions either in cgs (ml & gm) or mks (Lt & kg).
Mathematical expression
Aqueous Sodium chloride brine solution is 25% (w/v). Calculate mass of sodium chloride in the solution?
Answer:
It is an aqueous brine solution (i.e. NaCl + Water)
Let volume of Brine solution = 100 mL
Substituting in the above formula
