Concentration of Solution Percentage by Mass


 
 
Concept Explanation
 

Concentration of Solution Percentage by Mass

The concentration or strength of a solution depends on how much solute is dissolved in it. The amount of solute dissolved in a unit quantity (volume or mass) of a solution is known as the concentration or strength of the solution. There are various methods to express the concentration of a solution. One of the method is to express the concentration of Solution as Percentage:

Percentage: The concentration of a solution may be expressed in terms of percentage, by mass or by volume.

Percentage by mass :-

It is defined as the number of parts by mass of the solute dissolved per hundred parts by mass of the solution. For example, a 10% by mass of a solution of urea in water will have 10 g of urea dissolved in 90 g of water.  The concentration of the solution is then expressed as

frac{10g}{10g+90g}=frac{10}{100};X100=10%;urea;by;mass

Similarly, the concentration of a solution containing 5 g of NaCl in 95 g of water can be expressed as

frac{5g}{5g+95g}=frac{5}{100};X100=5%;NaCl;by;mass

Thus,; percentage ;by; mass= frac{mass;of;solute}{mass; of;solution}times 100

Example :- 

  • A syrup is prepared by dissolving 250 g sucrose in 150 g  of water. Calculate the mass percent of sucrose in the solution.
  • Solution :-
  •            We know that

                   Percentage ;by; mass= frac{mass;of;solute}{mass; of;solution}times 100

                However, Mass of solution = Mass of solute + Mass of solvent = 250 + 150  = 400 gm

     Mass: %:=:frac{250g:X:100}{400:g}:=:62.5%

    Volume Percentage :-

    It may be defined as the volume of solute in ml present in 100 ml of the solution.

        Percentage: by: Volume = frac{Volume: of: the:solute}{Volume: of: the: solution}: X :100

    For example, a 20% solution of acetic acid (by volume) means 20 ml of acetic acid  is present in 100 ml of solution.

    Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Which of the following are correct :

    (a) The concentration or strength of a solution depends on how much solute is dissolved in it.

    (b) The amount of solute dissolved in a unit quantity of a solution is known as the concentration or strength of the solution.

    (c) The concentration of a solution may be expressed in terms of percentage, by mass or by volume.

    Right Option : D
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    Explanation
    Question : 2

    A syrup is prepared by dissolving 250 g sucrose in 150 g of water. Calculate the mass percent of sucrose in the solution.

    Right Option : C
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    Explanation
    Question : 3

    The amount of solute dissolved in a ___________________ of a solution is known as the concentration or strength of the solution.

    Right Option : D
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    Explanation
     
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