*****************ANALYTICAL CHEMISTRY LAB REPORT*********************** YOU ONLY
ID: 520310 • Letter: #
Question
*****************ANALYTICAL CHEMISTRY LAB REPORT***********************
YOU ONLY NEED TO HELP ME WRITE THE "DISCUSSION" SECTION USING THE INFORMATION BELOW.
Standardization of 0.0500M Silver Nitrate (AgNO3)
Experimental
0.0292g of NaCl was weighed on the analytical balance and added into the 100ml flask. 10ml of DI water was added to the NaCl inside the 100ml flask. About 5 drops of the indicator were added to the solution inside the 100ml flask for both methods that was performed in this experiment. The solution was then titrated with 0.05M AgNO3 solution added to a 50ml burrete after the burrete has been cleaned with DI water and about 2ml of the AgNO3. Then titration was performed until the end was reached. The volume of titrant (AgNO3) needed was recorded as the experiment progress. Mohr’s method was done first using dilute potassium chromate as the indicator for the four trials that was done and the change is expected to go from yellow to reddish depending on the amount of indicator that was added to the solution. Fajan’s method makes use of dichlorofluorescein indicator with 1ml of dextrin and the color is expected to go from yellow to pink. The process was repeated for all the 4 trials that were performed in this experiment.
Results
Table 1: Total volume of Silver Nitrate (AgNO3) Used for Mohr’s Method
Trials
Mass of Sodium Chloride NaCl (g)
Initial Volume of Silver Nitrate (In Burette) [ml]
Fina Volume of Silver Nitrate (AgNO3) (ln Burette) [ml]
Total Volume of Silver Nitrate (AgNO3) Used (ml)
Total Volume of Silver Nitrate (AgNO3) Used (L)
Concentration of Silver Nitrate (AgNO3)
(M)
1
0.0290
9.50
18.5
9.00
0.0090
0.0551
2
0.0301
18.5
27.5
9.00
0.0090
0.0572
3
0.0287
6.00
15.00
9.00
0.0090
0.0546
4
0.0280
15.0
24.5
9.50
0.0095
0.0504
Table 2: Total volume of Silver Nitrate (AgNO3) Used for Fajan’s Method
Trials
Weight of Sodium Chloride NaCl (g)
Initial Volume of Silver Nitrate (In Burette) [ml]
Fina Volume of Silver Nitrate (AgNO3) (ln Burette) [ml]
Total Volume of Silver Nitrate (AgNO3) Used (ml)
Total Volume of Silver Nitrate (AgNO3) Used (L)
Concentration of Silver Nitrate (AgNO3)
(M)
1
0.0354
5.00
13.5
8.50
0.0085
0.0706
2
0.0300
13.50
23.0
9.50
0.0095
0.0540
3
0.0296
23.0
33.0
10.0
0.0100
0.0507
4
0.0270
33.0
43.0
10.0
0.0100
0.0462
Calculations
Concentration of Silver Nitrate (AgNO3) (M) for Fajan’s Method
Moles of NaCl Used = grams of NaCl × Molar Mass of NaCl
= 0.0354g × = 0.0006mol of NaCl
Moles of AgNO3 Used = moles of NaCl × mol ratio between NaCl & AgNO3
= 0.0006mols NaCl × = 0.0006 mol of AgNO3
Volume of AgNO3 Used = 0.0085L
Molarity of AgNO3 = = = 0.0706M
Concentration of Silver Nitrate (AgNO3) (M) for Mohr’s Method
Moles of NaCl Used = grams of NaCl × Molar Mass of NaCl
= 0.0290g × = 0.0005mol of NaCl
Moles of AgNO3 Used = moles of NaCl × mol ratio between NaCl & AgNO3
= 0.0005mols NaCl × = 0.0005 mol of AgNO3
Volume of AgNO3 Used = 0.0090L
Molarity of AgNO3 = = = 0.0551M
Discussions
The result suggests that my concentration of AgNO3 was reliable considering the molarity that was obtained from trail 1 to 4 both method with the exclusion of trial 1 and 4 in the Fajan’s method. It can be assumed that source of error was likely to come from either reading the burrete reading accurately or weighing error
Trials
Mass of Sodium Chloride NaCl (g)
Initial Volume of Silver Nitrate (In Burette) [ml]
Fina Volume of Silver Nitrate (AgNO3) (ln Burette) [ml]
Total Volume of Silver Nitrate (AgNO3) Used (ml)
Total Volume of Silver Nitrate (AgNO3) Used (L)
Concentration of Silver Nitrate (AgNO3)
(M)
1
0.0290
9.50
18.5
9.00
0.0090
0.0551
2
0.0301
18.5
27.5
9.00
0.0090
0.0572
3
0.0287
6.00
15.00
9.00
0.0090
0.0546
4
0.0280
15.0
24.5
9.50
0.0095
0.0504
Explanation / Answer
Assuming some source errors cited in your discussion in the experiment, looks like there is some positive
error in Mohr's method for 2nd and 3rd trial. Fajan's method shows pretty accurate results and are much
more reliable like you said, considering 2nd and 3rd trials again. But on a whole, the aim of the experiment
is fulfilled i.e) to show that Fajan's method is the best for detecting end point.
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