1. SCH3U Solutions and Solubility
8.5 Acid-Base Reactions
SCH3U
Solutions and Solubility

2. Reactions Involving Acids
Acids take part in several characteristic reactions:
Active metals react with acids in a single displacement reaction
active metal + acid  hydrogen + ionic compound
Mg(s) HCl(aq)  H2(g) MgCl2(aq)

3. Reactions Involving Acids
All acids react with carbonates in a double displacement reaction
carbonate + acid  carbon dioxide + water + ionic compound
Na2CO3(s) + 2HNO3(aq)  CO2(g) + H2O(l) + 2NaNO3(aq)

4. Reactions Involving Acids
Acids undergo precipitation reactions with some ionic compounds
ionic compound + acid  precipitate acid
Pb(NO3)2(aq) + 2HI(aq)  PbI2(s) + 2HNO3(aq)

5. Reactions Involving Acids
Acids react with bases in another double displacement reaction often called a neutralization reaction
base acid  ionic compound water
NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(l)

6. SCH3U Solutions and Solubility
8.5 Acid-Base Titration
SCH3U
Solutions and Solubility

7. Acid-Base Titration Titration Titrant
a laboratory procedure involving the carefully measured and controlled adding of a solution from a buret into a measured volume of a sample solution
it is used to determine the concentration of substances in solution
Titrant
the solution in the buret during a titration (standard solution with KNOWN concentration)

8. Titration Apparatus

9. Titration of an Acid with a Base
In the buret  standard solution of base (KNOWN concentration)
In the flask  precise volume of acid (UNKNOWN concentration)
In the flask  indicator to detect the end point

10. Titration of a Base with an Acid
In the buret  standard solution of acid (KNOWN concentration)
In the flask  precise volume of base (UNKNOWN concentration)
In the flask  indicator to detect the end point

11. The Endpoint
Endpoint
the point in a titration at which the indicator changes colour
this is at, or close to, the point at which the titrant and sample in the flask have completely reacted
PHTH titration

12. The Endpoint

13. Steps of a Titration Place standard solution in buret
Place a precise volume of a solution of unknown concentration in a flask
Add an indicator to the flask
Record the volume in the buret as your initial reading
Open the stopcock of the buret and allow the standard solution to enter the flask, while swirling the flask
Slow down the flow of standard solution being added to ensure you don’t surpass the endpoint by too much
Once the end point is reached, record the final volume in the buret
Subtract the initial volume from the final volume in the buret to obtain the total volume of standard solution used to neutralize the unknown solution.

14. A Titration Sample Problem
25.0 mL of an acid rain sample containing sulfurous acid was analyzed in a laboratory using a titration with a standard solution of sodium hydroxide ( mol/L). Use the evidence given in the following table to determine the concentration of the sulfurous acid.

15. HOMEWORK Read Section 8.5 (pg. 393 – 397)
Answer “Practice” #6 – 11 on pg. 399 – 400