Top topic this week
Back to FAQs
Related FAQs
Frequently Asked Question
Questions asked by users might not always be phrased in the clearest way.
A 25.00 ml sample of 0.1306 m AgNO3 is being titrated with 0.1194 m KSCN. Calculate the pscn AFTER ADDITION of 20.0 ml KSCN. ksp for AgSCN = 1.1x10^12: a. 10.25, b. 11.30, c.10.92, d. 11.51
Accepted Answer
Here's the solution:
1. Determine the moles of Ag+ and SCN- initially:
Moles of Ag+ = (0.1306 mol/L)
(0.02500 L) = 0.003265 mol
Moles of SCN- = (0.1194 mol/L)
(0.0200 L) = 0.002388 mol
2. Determine the moles of Ag+ and SCN- remaining after reaction:
Since Ag+ and SCN- react in a 1:1 ratio, 0.002388 mol of Ag+ will react with 0.002388 mol of SCN-.
Remaining Ag+: 0.003265 mol - 0.002388 mol = 0.000877 mol
Remaining SCN-: 0.002388 mol - 0.002388 mol = 0 mol
3. Calculate the concentration of SCN- :
Total volume = 25.00 mL + 20.00 mL = 45.00 mL = 0.04500 L
Since the SCN- concentration is extremely small due to the reaction with Ag+, we need to use the Ksp expression to find it.
4. Use the Ksp expression to find [SCN-]:
Ksp = [Ag+][SCN-] = 1.1 x 10^-12
[SCN-] = Ksp / [Ag+] = (1.1 x 10^-12) / (0.000877 mol / 0.04500 L) = 5.6 x 10^-10 M
5. Calculate pSCN:
pSCN = -log[SCN-] = -log(5.6 x 10^-10) = 9.25
Therefore, the closest answer is (a) 10.25.
Articles you might like