<< Chapter < Page Chapter >> Page >

Molar volumes of gases

Molar volume of gases
1 mole of gas occupies 22,4 dm 3 at S.T.P.

This applies to any gas that is at standard temperature and pressure. In grade 11 you will learn more about this and the gas laws.

Molar concentrations of liquids

A typical solution is made by dissolving some solid substance in a liquid. The amount of substance that is dissolved in a given volume of liquid is known as the concentration of the liquid. Mathematically, concentration (C) is defined as moles of solute (n) per unit volume (V) of solution.

C = n V

For this equation, the units for volume are dm 3 . Therefore, the unit of concentration is mol · dm - 3 . When concentration is expressed in mol · dm - 3 it is known as the molarity (M) of the solution. Molarity is the most common expression for concentration.

Do not confuse molarity (M) with molar mass (M). Look carefully at the question in which the M appears to determine whether it is concentration or molar mass.

Concentration is a measure of the amount of solute that is dissolved in a given volume of liquid. It is measured in mol · dm - 3 . Another term that is used for concentration is molarity (M)

If 3,5 g of sodium hydroxide (NaOH) is dissolved in 2,5 dm 3 of water, what is the concentration of the solution in mol · dm - 3 ?

  1. n = m M = 3 , 5 40 = 0 , 0875 mol
  2. C = n V = 0 , 0875 2 , 5 = 0 , 035

    The concentration of the solution is 0,035 mol · dm - 3 or 0,035 M

You have a 1 dm 3 container in which to prepare a solution of potassium permanganate ( KMnO 4 ). What mass of KMnO 4 is needed to make a solution with a concentration of 0,2 M ?

  1. C = n V


    n = C × V = 0 , 2 × 1 = 0 , 2 mol
  2. m = n × M = 0 , 2 × 158 , 04 = 31 , 61 g

    The mass of KMnO 4 that is needed is 31,61 g .

How much sodium chloride (in g) will one need to prepare 500 cm 3 of solution with a concentration of 0,01 M ?

  1. V = 500 1 000 = 0 , 5 dm 3
  2. n = C × V = 0 , 01 × 0 , 5 = 0 , 005 mol
  3. m = n × M = 0 , 005 × 58 , 45 = 0 , 29 g

    The mass of sodium chloride needed is 0,29 g

Molarity and the concentration of solutions

  1. 5,95 g of potassium bromide was dissolved in 400 cm 3 of water. Calculate its molarity.
  2. 100 g of sodium chloride (NaCl) is dissolved in 450 cm 3 of water.
    1. How many moles of NaCl are present in solution?
    2. What is the volume of water (in dm 3 )?
    3. Calculate the concentration of the solution.
    4. What mass of sodium chloride would need to be added for the concentration to become 5,7 mol · dm - 3 ?
  3. What is the molarity of the solution formed by dissolving 80 g of sodium hydroxide ( NaOH ) in 500 cm 3 of water?
  4. What mass (g) of hydrogen chloride ( HCl ) is needed to make up 1000 cm 3 of a solution of concentration 1 mol · dm - 3 ?
  5. How many moles of H 2 SO 4 are there in 250 cm 3 of a 0,8 M sulphuric acid solution? What mass of acid is in this solution?

Stoichiometric calculations

Stoichiometry is the calculation of the quantities of reactants and products in chemical reactions. It is also the numerical relationship between reactants and products. In representing chemical change showed how to write balanced chemical equations. By knowing the ratios of substances in a reaction, it is possible to use stoichiometry to calculate the amount of either reactants or products that are involved in the reaction. The examples shown below will make this concept clearer.

Questions & Answers

Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
The fundamental frequency of a sonometer wire streached by a load of relative density 's'are n¹ and n² when the load is in air and completly immersed in water respectively then the lation n²/na is
Mukesh Reply
Properties of longitudinal waves
Sharoon Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Siyavula textbooks: grade 10 physical science [caps]. OpenStax CNX. Sep 30, 2011 Download for free at http://cnx.org/content/col11305/1.7
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Siyavula textbooks: grade 10 physical science [caps]' conversation and receive update notifications?