Concentration of acids

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Concentration of acids
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How to make two molar solution of nitric acid?
Remember! Acid is added to the water in dilution!
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How to calculate the concentration of a solution?
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Amount of solute volume of solvent
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The concentration of solution B is _________ of
the concentration in A.
twice
The concentration of solution C is ________ of
that in B and _________ as solution A.
half
same
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Density mass / volume
Solute Solvent
Concentration mass / volume
solute
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What is the concentration of the solution below?
5 grams of sodium chloride dissolves in 10 cm3 of
water.
Concentration
0.5 g / cm3
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Molarity (M) is a measure of concentration of
common solution
Molarity
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1 dm3 1 litre 1000 cm3 1000 ml
1000 cm3 10 cm ? 10 cm ? 10 cm
0.1m ? 0.1 m ? 0.1m
10-3 m3
10
23 g of sodium solid
1 litre of water
1 mol
Molarity ?
1 M
1 dm3
58.5 g of NaCl
1 mol
250 cm3 of water
(250 /1000) dm3
4 M
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Complete the table below
2
12
500
100
6.02 ? 1023
Mole
12
The unit mole is used to count the particles as
they are in a large quantity.
Unit of mole is mol
How many carbon-12 atoms in 1 mole of it?
A 1 million
C 6.02 ? 1023
B 1 trillion
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Number of particles in one mole must be the same
6.02 ? 1023
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Which one in the following has the greatest
number of particles?
A 1 mole of helium
B 1 mole of hydrogen gas
C 1 mole of hydrogen ions
D 1 mole of copper
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1 mole of hydrogen gas
______ mole(s) of hydrogen atoms
2
1 mole of water
______ mole(s) of hydrogen atoms ______
mole(s) of oxygen atoms
2
1
1 mole of sodium chloride
______ mole(s) of sodium ions ______ mole(s)
of chloride ions
1
1
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Number of particles
Number of moles
6.02 ? 1023
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Relative atomic mass
Average mass of the isotopes in the element
compared with a carbon-12 atom
The atomic mass of Cl
35 ? 75 37 ? 25
35.5
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Relative molecular mass
Average mass of a molecule is adding the atomic
masses of the atoms in a molecule
The molecular mass of CO2
atomic mass of C atomic mass of O
12.0 2 ? 16.0 44.0
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Relative formula mass
Sum of the atomic masses of all atoms present in
the formula
The formula mass of NaCl
atomic mass of Na atomic mass of Cl
23.0 35.5 58.5
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Molar Mass
Same as
Atomic / molecular / formula mass in grams
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(No Transcript)
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Molecular mass of chlorine 2 ? 35.5 g 71 g
Molecular mass of carbon dioxide
(12 2 ? 16) g 44 g
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Molar mass of CuCl2
(63.5 2 ? 35.5)g 134.5 g
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Mass of a substance in g
Number of moles
Molar mass in g
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What is the number of moles of atoms in 8 g of
iron?
The molar mass of iron Fe 56 g
Number of moles of Fe atom
8 g / 56 g mol ?1
0.143 mole
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What is the number of moles of 9 g of water?
The molar mass of hydrogen H oxygen O are 1 g
16 g respectively
Number of moles of water
9 g / 18 g mol ?1
0.5 mole
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What is the number of moles of 15.95 g of
copper(II) sulphate?
Number of moles of CuSO4
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What is the mass of 0.3 mole of hydrogen chloride?
Number of moles of HCl mass / molar mass
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Calculate the number of moles of oxygen atoms in
23 g of nitrogen dioxide NO2 .
Number of moles of NO2 23 / 46 0.5 mole
1 molecule of NO2 has 2 oxygen atoms
?1 mole of NO2 has 2 moles of oxygen atoms
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Standard solution
A solution with a known concentration
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How to prepare standard solution?
1. Dissolve a pure solid in water
2. Dilute a more concentrated solution
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Apparatus required
Electronic balance or triple beam balance
Volumetric flask, burette, pipette, measuring
cylinder
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Preparation of standard solution from a pure solid
1. Calculate the mass of a solid needed
2. Weigh the mass accurately
3. Dissolve the solid in about 100 cm3 of
distilled water
4. Pour the solution into a volumetric flask
5. Add distilled water carefully to the
graduation mark
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Calculate the mass of solute required to prepare
500 cm3 of 0.5 M KCl solution
Molarity
Number of mole of KCl
0.5 M ? (500 / 1000)dm3 0.25 mole
Mass of KCl number of mole of KCl ? molar mass
0.25 ? (39 35.5) 18.625 g
18.63 g
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Preparation of a standard solution by diluting a
solution

• Adding distilled water to the solution

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On dilution
The volume of solution _________
increases
decreases
The molarity of the solution ________
the same
The amount of solute is ___________
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200 cm3 of 0.1 M NaOH solution
No. of mole of NaOH used
0.1 ? (200 / 1000) 0.02 mol
Mass of NaOH
dm3
0.02 ? (23 16 1)
Molar mass of NaOH
0.8 g
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Moles of solute M1V1 M2V2 moles of solute