Transcript Redox Stoichiometry - Salisbury Composite High School

Redox Stoichiometry
• A redox reaction can be used along with the
stoichiometric method in order to predict the
quantity of chemical involved in a chemical
reaction.
Redox Stoichiometry involves several
assumptions:
•
•
•
•
Reactions are spontaneous
Reactions are fast / immediate
Reactions are quantitative (>99%)
Reactions occur in stoichiometric ratios
Steps for Redox Stoichiometry
1. Write a balanced redox chemical equation
2. Convert the given measurement to moles
3. Calculate the moles of the required substance
using the balanced equation
4. Convert the calculated moles to the required
quantity using the appropriate conversion
factor
5. Check your answer!
Redox Titrations
• used to determine the concentrations of
substances in a solution.
• the progressive addition of one reagent to
another until an endpoint is reached.
▫ the endpoint is indicated by a color change,
often due to ion colors in solution
 Ex)
• the measured quantity taken when the
endpoint occurs is called the equivalence
point.
• substance in the burette is
called the titrant.
• A standard solution
(concentration is known) is
used in the titration
Redox Titration
Beginning
Endpoint
Example:
Problem: What is the concentration of a potassium
permanganate solution?
Design: In order to standardize a freshly prepared
sample of potassium permanganate, it is titrated
against samples of acidic tin(II)chloride solution.
The tin(II)chloride is the primary standard.
Titration of 10.00 mL of 0.200 mol/L acidified tin(II) solution with
KMnO4(aq)
Trial
1
2
3
4
Final Vol (ml)
18.4
35.3
17.3
34.1
Init. Vol (ml)
1.0
18.4
0.6
17.3
Vol Added (ml)
17.4
16.9
16.7
16.8
Endpoint Color
Dk pink Lt pink
Lt pink
Lt pink