Week 6: Reactions in aqueous solutions
Objectives
Molarity: Calculate the molarity of a solution.
Determine the concentration of an ion in a solution.
1. Interconvert between molarity, moles, volume and mass of a solution.
2. Perform dilution calculations.
3. Expressing concentration in: % (m/m), % (m/v), % (v/v), parts per
million (ppm), parts per billion (ppb) and molality.
4. Conversion of concentration units between: mol/L, mol/kg, ppm, ppb,
% (m/m), % (m/V), density or specific gravity.
5. Differentiate between strong, weak and non-electrolytes.
6. Write a balanced equation for the dissociation of a strong electrolyte
and a weak electrolyte in water.
7. Use solubility guidelines to determine if a salt (ionic compound) is
soluble or insoluble in an aqueous solution.
8. Complete and balance precipitation reaction equations (remember to
indicate state: s, l, g, aq).
9. Predict the formation of precipitates and spectator ions.
10. Determine oxidation numbers for atoms.
11. Identify oxidation and reduction reagents and write half-reactions for
oxidation and reduction.
12. Predict spontaneous redox reactions by using oxidation activity
series.
13. Identify strong and weak acids and bases.
14. Complete and balance neutralisation reaction equations (remember
to indicate state: s, l, g, aq).
15. Use stoichiometry in a balanced equation to convert quantitative
information of one substance into quantitative information for another
substance in the reaction
16. Perform limiting reagent calculations (LO#6).
17. Perform titration calculations (precipitation, neutralisation and redox
reactions
General Properties of Aqueous Solutions
A solution is a homogeneous mixture of two or more substances.
(Section 1.2) The substance present in the greatest quantity is usually
,called the solvent, and the other substances are called solutes; they are
said to be dissolved in the solvent. When a small amount of sodium
chloride (NaCl) is dissolved in a large quantity of water, for example,
water is the solvent and sodium chloride is the solute.
Electrolytes and Nonelectrolytes
At a young age we learn not to bring electrical devices into the bathtub
so as not to electrocute ourselves. That is a useful lesson because most
of the water we encounter in daily life is electrically conducting. Pure
water, however, is a very poor conductor of electricity. The conductivity
of bathwater originates from the substances dissolved in the water, not
from the water itself.Not all substances that dissolve in water make the
resulting solution conducting.
Figure 4.2 shows a simple experiment to test the electrical conductivity
of three solutions: pure water, a solution of table sugar (sucrose) in
water, and a solution of table salt (NaCl) in water. A light bulb is
connected to a battery-powered electrical circuit that contains two
electrodes submerged in a beaker of each solution. In order for the light
bulb to turn on, there must be an electrical current (that is, a flow of
electrically charged particles) between the two electrodes immersed in
the solution. Because the light bulb does not turn on in pure water, we
conclude that there are not enough charged particles in pure water to
create a circuit; water must then mostly exist as H2O molecules. The
solution containing sucrose 1C12H22O112 also does not turn on the
light bulb; therefore, we conclude that the sucrose molecules in solution
are uncharged. But the solution containing NaCl does provide enough
charged particles to create an electrical circuit and turn on the light bulb.
This is experimental evidence that Na+ and Cl- ions are formed in
aqueous solution. A substance (such as NaCl) whose aqueous solutions
contain ions is called an electrolyte. A substance (such as C12H22O112
that does not form ions in solution is called a nonelectrolyte. The
different classifications of NaCl and C12H22O11 arise largely because
NaCl is an ionic compound, whereas C12H22O11 is a molecular
compound.
, General Properties of Aqueous Solutions
• Solution - a homogeneous mixture – Solute: the component that is
dissolved – Solvent: the component that does the dissolving Generally,
the component present in the greatest quantity is considered to be the
solvent. Aqueous solutions are those in which water is the solvent.
• Electrolytes and Nonelectrolytes – Electrolyte: substance that dissolved
in water produces a solution that conducts electricity • Contains ions
Objectives
Molarity: Calculate the molarity of a solution.
Determine the concentration of an ion in a solution.
1. Interconvert between molarity, moles, volume and mass of a solution.
2. Perform dilution calculations.
3. Expressing concentration in: % (m/m), % (m/v), % (v/v), parts per
million (ppm), parts per billion (ppb) and molality.
4. Conversion of concentration units between: mol/L, mol/kg, ppm, ppb,
% (m/m), % (m/V), density or specific gravity.
5. Differentiate between strong, weak and non-electrolytes.
6. Write a balanced equation for the dissociation of a strong electrolyte
and a weak electrolyte in water.
7. Use solubility guidelines to determine if a salt (ionic compound) is
soluble or insoluble in an aqueous solution.
8. Complete and balance precipitation reaction equations (remember to
indicate state: s, l, g, aq).
9. Predict the formation of precipitates and spectator ions.
10. Determine oxidation numbers for atoms.
11. Identify oxidation and reduction reagents and write half-reactions for
oxidation and reduction.
12. Predict spontaneous redox reactions by using oxidation activity
series.
13. Identify strong and weak acids and bases.
14. Complete and balance neutralisation reaction equations (remember
to indicate state: s, l, g, aq).
15. Use stoichiometry in a balanced equation to convert quantitative
information of one substance into quantitative information for another
substance in the reaction
16. Perform limiting reagent calculations (LO#6).
17. Perform titration calculations (precipitation, neutralisation and redox
reactions
General Properties of Aqueous Solutions
A solution is a homogeneous mixture of two or more substances.
(Section 1.2) The substance present in the greatest quantity is usually
,called the solvent, and the other substances are called solutes; they are
said to be dissolved in the solvent. When a small amount of sodium
chloride (NaCl) is dissolved in a large quantity of water, for example,
water is the solvent and sodium chloride is the solute.
Electrolytes and Nonelectrolytes
At a young age we learn not to bring electrical devices into the bathtub
so as not to electrocute ourselves. That is a useful lesson because most
of the water we encounter in daily life is electrically conducting. Pure
water, however, is a very poor conductor of electricity. The conductivity
of bathwater originates from the substances dissolved in the water, not
from the water itself.Not all substances that dissolve in water make the
resulting solution conducting.
Figure 4.2 shows a simple experiment to test the electrical conductivity
of three solutions: pure water, a solution of table sugar (sucrose) in
water, and a solution of table salt (NaCl) in water. A light bulb is
connected to a battery-powered electrical circuit that contains two
electrodes submerged in a beaker of each solution. In order for the light
bulb to turn on, there must be an electrical current (that is, a flow of
electrically charged particles) between the two electrodes immersed in
the solution. Because the light bulb does not turn on in pure water, we
conclude that there are not enough charged particles in pure water to
create a circuit; water must then mostly exist as H2O molecules. The
solution containing sucrose 1C12H22O112 also does not turn on the
light bulb; therefore, we conclude that the sucrose molecules in solution
are uncharged. But the solution containing NaCl does provide enough
charged particles to create an electrical circuit and turn on the light bulb.
This is experimental evidence that Na+ and Cl- ions are formed in
aqueous solution. A substance (such as NaCl) whose aqueous solutions
contain ions is called an electrolyte. A substance (such as C12H22O112
that does not form ions in solution is called a nonelectrolyte. The
different classifications of NaCl and C12H22O11 arise largely because
NaCl is an ionic compound, whereas C12H22O11 is a molecular
compound.
, General Properties of Aqueous Solutions
• Solution - a homogeneous mixture – Solute: the component that is
dissolved – Solvent: the component that does the dissolving Generally,
the component present in the greatest quantity is considered to be the
solvent. Aqueous solutions are those in which water is the solvent.
• Electrolytes and Nonelectrolytes – Electrolyte: substance that dissolved
in water produces a solution that conducts electricity • Contains ions
