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Using the combined gas law

  1. An enclosed gas(i.e. one in a sealed container) has a volume of 300 cm 3 and a temperature of 300 K . The pressure of the gas is 50 kPa . Calculate the number of moles of gas that are present in the container.
  2. What pressure will 3 mol of gaseous nitrogen exert if it is pumped into a container that has a volume of 25 dm 3 at a temperature of 29 0 C ?
  3. The volume of air inside a tyre is 19 litres and the temperature is 290 K . You check the pressure of your tyres and find that the pressure is 190 kPa . How many moles of air are present in the tyre?
  4. Compressed carbon dioxide is contained within a gas cylinder at a pressure of 700 kPa. The temperature of the gas in the cylinder is 310 K and the number of moles of gas is 13 mols of carbon dioxide. What is the volume of the gas inside the cylinder?

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?

Questions & Answers

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
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
What makes metals better to use as wires than non-metals? (please link to bonding type)??? HELP
Yash Reply

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Source:  OpenStax, Chemistry grade 10 [caps]. OpenStax CNX. Jun 13, 2011 Download for free at http://cnx.org/content/col11303/1.4
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