•During dilution, the amounts of an acid or base in solution do not change- it is the volume of the solution that increases- so that the concentration decreases.
•The change in concentration can be determined using :
C1 x V1 = C2 X V2
•The pH increases when a solution of an acid is diluted.
Example:
10.0mL of 0.1M HCl is diluted to 30.0mL. Calculate the pH of the diluted solution.
V1= 10.0mL V2=30.0mL C1=0.1M C2=?
C1 x V1 = C2 X V2
C2 = C1 x V1 / V2
C2 = 0.1 x 10.0 /30.0 = 0.03M
pH= -log[H3O+]= -log[0.03] =1.5
•The pH decreases when a solution of an a base is diluted.
Example:
15.0mL of 0.02M NaCl is diluted to 60.0mL. Calculate the pH of the diluted solution.
V1= 15.0mL V2=60.0mL C1=0.02M C2=?
C1 x V1 = C2 X V2
C2 = C1 x V1 / V2
C2 = 0.02 x 15.0 /60.0 = 0.005M
Since base- to find H3O+ = 10-14 /0.005 =2x10-12
pH= -log[H3O+]= -log[2x10-12] =11.7
Reactions of acids
•Acids react with a number of other elements or compounds.
•Neutralisation Reaction:
Acid + Base → Salt + Water.
Eg: HCl (aq) + NaOH (aq)→ NaCl(aq)+H2O (l)
•Single Replacement:
Acid + Metal → Salt + Hydrogen gas.
Eg: 2HCl ( aq) + Mg (s) → MgCl2 (aq) + H2 (g)
Neutralisation
•If the base added during neutralisation contains a carbonate, then the following reaction occurs:
ACID + CARBONATE BASEà SALT + WATER + CARBON DIOXIDE
•Eg. hydrochloric acid + sodium bicarbonate à sodium chloride + water + carbon dioxide
HCl (aq) + NaHCO3 (aq) à NaCl (aq) + H2O (aq) + CO2(g)
Limewater is used to test for the presence of carbon dioxide gas.
•The change in concentration can be determined using :
C1 x V1 = C2 X V2
•The pH increases when a solution of an acid is diluted.
Example:
10.0mL of 0.1M HCl is diluted to 30.0mL. Calculate the pH of the diluted solution.
V1= 10.0mL V2=30.0mL C1=0.1M C2=?
C1 x V1 = C2 X V2
C2 = C1 x V1 / V2
C2 = 0.1 x 10.0 /30.0 = 0.03M
pH= -log[H3O+]= -log[0.03] =1.5
•The pH decreases when a solution of an a base is diluted.
Example:
15.0mL of 0.02M NaCl is diluted to 60.0mL. Calculate the pH of the diluted solution.
V1= 15.0mL V2=60.0mL C1=0.02M C2=?
C1 x V1 = C2 X V2
C2 = C1 x V1 / V2
C2 = 0.02 x 15.0 /60.0 = 0.005M
Since base- to find H3O+ = 10-14 /0.005 =2x10-12
pH= -log[H3O+]= -log[2x10-12] =11.7
Reactions of acids
•Acids react with a number of other elements or compounds.
•Neutralisation Reaction:
Acid + Base → Salt + Water.
Eg: HCl (aq) + NaOH (aq)→ NaCl(aq)+H2O (l)
•Single Replacement:
Acid + Metal → Salt + Hydrogen gas.
Eg: 2HCl ( aq) + Mg (s) → MgCl2 (aq) + H2 (g)
Neutralisation
•If the base added during neutralisation contains a carbonate, then the following reaction occurs:
ACID + CARBONATE BASEà SALT + WATER + CARBON DIOXIDE
•Eg. hydrochloric acid + sodium bicarbonate à sodium chloride + water + carbon dioxide
HCl (aq) + NaHCO3 (aq) à NaCl (aq) + H2O (aq) + CO2(g)
Limewater is used to test for the presence of carbon dioxide gas.