Close Menu
    Facebook X (Twitter) Instagram
    ScienceMotive
    • Class 9
      • Matter in Our Surroundings
      • Is Matter Around Us Pure
      • Atoms and Molecules
      • Structure of the Atom
      • The Fundamental Unit of Life
    • Class 10
      • Chapter 1: Chemical Reactions and Equations
      • Chapter 2: Acids, Bases & Salts
      • Chapter 3: Metals & Non-Metals
      • Chapter 4: Carbon and its Compounds
      • Chapter 5: Periodic Classification of Elements
      • Chapter 6: Life Processes
      • Chapter 7: Control and Coordination
      • Chapter 8: How Do Organisms Reproduce?
      • Chapter 9: Heredity and Evolution
      • Chapter 10: Light – Reflection and Refraction
      • Chapter 11: Human Eye and the Colourful World
      • Chapter 12: Electricity
      • Chapter 13: Magnetic Effects of Electric Current
      • Chapter 14: Sources of Energy
      • Chapter 15: Our Environment
      • Chapter 16: Management of Natural Resources
    • Class 11
      • Chemisrty 11
        • Chapter – 1 Some Basic Concepts of Chemistry
        • Chapter – 2 Structure Of Atom
        • Chapter – 3 Classification of Elements and Periodicity in Properties
        • Chapter – 4 Chemical Bonding and Molecular Structure
        • Chapter – 5 States of Matter
        • Chapter – 6 Thermodynamics
        • Chapter – 7 Equilibrium
        • Chapter – 8 Redox Reaction
        • Chapter – 10 s-Block Elements
        • Chapter – 13 Hydrocarbons
    • Class 12
      • Chemistry 12
        • The Solid State
        • Solutions
        • Electrochemistry
        • Chemical Kinetics
        • Surface Chemistry
        • p – Block Elements
        • d & f Block Elements
        • Coordination Compounds
        • Haloalkanes and Haloarenes
        • Alcohols, Phenols and Ethers
        • Aldehydes, Ketones and Carboxylic Acids
        • Amines
        • Biomolecules
        • Polymers
        • Chemistry in Everyday Life
    • Practice Questions
      • +1
      • +2
    • Test Series
      • Class 9 Test Series
      • Class 10 Test Series
      • Class 11 Test Series
      • Class 12 Test Series
    • World
      • Current Affairs
      • General Knowledge
    ScienceMotive
    Home » Expressing Concentration Terms with Formula

    Expressing Concentration Terms with Formula

    Dr. Vikas JasrotiaBy Dr. Vikas JasrotiaOctober 1, 2020No Comments
    Share
    Facebook WhatsApp Telegram Twitter Email

    Expressing Concentration Terms with Formula

    Concentration Can be Expressed in the Following Ways:

    (1) Mass percent (w/w or m/m): It is defined as the number of parts solute present in 100 parts by mass of solution. i.e.
    Mass % of a component =   Mass of solute  × 100
                                                          Mass of solution

    (2) Molarity (M): It is defined as the number of moles of solute dissolved per liter of solution. i.e.                                                             
    Molarity (M) = Number of moles of solute (n)/The volume of solution in litre (V)
    1 M NaOH solution means 1 mole of NaOH is present in 1 L of solution.
    Molarity equation: M1V1   =    M2V2
    (Before dilution) =    (After Dilution)
    The molarity of a solution decreases in increasing temperature. The molarity of pure water is 55.56 mol L-1.

    (3) Molality (m) = It is number of moles of solute dissolved per 1000g (1kg) of solvent.
     Molality =  Number of moles of solute/Mass of solvent in kg
    Among the above concentration terms, Molarity depends on temperature because it is related to volume, which changes with temperature. Whereas Molality is Independent of Temperature.

    Expressing Concentration Terms with Formula

    (4) Mole Fraction (x): It is defined as the ratio of the number of moles of a particular component to the total number of moles of solution. i.e.
    Mole fraction of a component =  Number of moles of the component/Total number of moles of all the components
    Let us consider we have two components 1 and 2. Therefore mole fraction of component 1 is x1, and component 2 is x2.
    x1 + x2 = 1 i.e the sum of the mole fractions of all the components in a solution is always equal to 1.

    Expressing Concentration Terms with Formula

    Numerical Problems 

    Que 1. According to nutritional guidelines from the US Department of Agriculture, the estimated average requirement for dietary potassium is 4.7 g. What is the estimated average requirement of potassium in moles?
    Ans 1. We Know
    Number of Moles = Given Mass/ Molecular Mass
    Number of moles of K = 4.7/39 = 0.12 mol
    Que 2. A litre of air contains 9.2 × 10-4 mol argon. What is the mass of Ar in a litre of air?
    Ans 2. We Know
    Number of Moles = Given Mass/ Molecular Mass
    9.2 × 10-4 = Mass of Argon (Given Mass) / 40
    Mass of Argon (Given Mass) = 9.2 × 10-4 × 40 = 0.037 g
    Que 3.  Copper is commonly used to fabricate electrical wire.  How many copper atoms are in 5.00 g of copper wire?
    Ans 3. We Know
    Number of Atoms/Molecules = Number of Moles × Avogadro’s No.
    No. of moles of Cu = 5/63.5 = 0.079 mol
    Number of Atoms = 0.079 × 6.022 × 1023
    = 4.74 × 1022 atoms of Cu
    Que 4. A packet of an artificial sweetener contains 40.0 mg of saccharin (C7H5NO3S).  Given that saccharin has a molar mass of 183.18 g/mol, how many saccharin molecules are in a 40.0 mg (0.0400g) sample of saccharin? How many carbon atoms are in the same sample?
    Ans 4.  We Know
    Number of Atoms/Molecules = Number of Moles × Avogadro’s No.
    No of Moles of Saccharin = 0.040/183.18 = 0.000218 mol
    Number of Molecules = 0.000218 × 6.022 × 1023 = 0.00131 × 1023
    = 1.3 × 1020 Molecules
    The compound’s formula (C7H5NO3S) shows that each molecule contains 7 carbon atoms, so the number of C atoms in the given sample is    7 × 1.3 × 1020 = 9.1 × 1020 atoms.

    Expressing Concentration Terms with Formula

    Advertisement
    Mass Percent Molality Molarity Mole Fraction
    Share. Facebook Twitter Pinterest LinkedIn Tumblr Email
    Dr. Vikas Jasrotia
    • Website

    Related Posts

    Class 11 Chemistry Half Yearly Question Paper

    September 30, 2024

    Redox Reaction

    June 13, 2024

    Equilibrium Class 11

    June 12, 2024
    Leave A Reply Cancel Reply

    READ ALSO

    Gravitation Class 9 Notes

    December 5, 2024

    Class 11 Chemistry Half Yearly Question Paper

    September 30, 2024

    Solid State Chemistry Class 12 Notes PDF Download

    September 10, 2024

    Redox Reaction

    June 13, 2024
    Class 9

    Gravitation Class 9 Notes

    By Dr. Vikas JasrotiaDecember 5, 2024

    Gravitation Class 9 Notes Gravitation Class 9 Notes Gravitation According to Newton, every object in…

    +1

    Class 11 Chemistry Half Yearly Question Paper

    By Dr. Vikas JasrotiaSeptember 30, 2024

    Class 11 Chemistry Half Yearly Question Paper Class 11 Chemistry Half Yearly Question Paper Time…

    +2

    Solid State Chemistry Class 12 Notes PDF Download

    By Dr. Vikas JasrotiaSeptember 10, 2024

    Solid State Chemistry Class 12 Notes PDF Download In our day-to-day life solids play…

    Advertisement
    Advertisement
    Facebook X (Twitter) Instagram Pinterest YouTube
    • Disclaimer
    • Contact Us
    • Privacy Policy 
    • Terms and Conditions
    © 2025 All Rights Reserved ScienceMotive.

    Type above and press Enter to search. Press Esc to cancel.