- #1
kirsten_2009
- 137
- 2
Homework Statement
Hello everyone,
I have completed a lab and I’m working on my report. I’m not sure if my work is correct but I would most definitely appreciate it if anyone could check it for me? I’m particularly having trouble finishing question #3. It’s worth a lot of my grade so I want to make sure I get it right! Thanks a lot in advance for all the time and help :)
Basically, the lab is a set of 2 redox titrations. For the first part, we standardized a KMnO₄ solution and in the second we titrated K₃[Fe(C₂O₄)₃]∙3H₂O
Homework Equations
2MnO₄²¯(aq) + 5C₂O₄²¯(aq) + 16H⁺(aq) à 2Mn²⁺(aq) + 10CO₂(g) + 8H₂O(l)
The Attempt at a Solution
1. Given a mass of 0.2349 g of Na₂C₂O₄ in 100 mL, what is the concentration of Na₂C₂O₄?
A:// 0.2349 g Na₂C₂O₄ = 1 mol Na₂C₂O₄ / 0.1 L = 0.0175 M
2. You used 6.9933 mL of KMnO₄, what is the concentration of the KMnO₄ solution?
A:// 0.00175 mol Na₂C₂O₄ x 2 mol KMnO₄ / 5 mol Na₂C₂O₄ = 0.0007 mol KMnO₄ / 0.0069933 L =
0.1001 M
3. You dissolved 0.2196 g of K₃[Fe(C₂O₄)₃]∙3H₂O in 100 mL. Given the concentration of KMnO₄ you just calculated and assuming that you used 7.1667 mL of it: determine the Mass Percent Composition of C₂O₄²¯ in K₃[Fe(C₂O₄)₃]∙3H₂O.
A:// 7.1667 mL x 1L / 1000 mL = 0.0071667 L x 0.1001mol / 1L = 0.000717386 mol KMnO₄
0.000717386 mol KMnO₄ x 5 mol Na₂C₂O₄ / 2 mol KMnO₄ = 0.0017935 mol Na₂C₂O₄ x 491.243 g/mol =
0.08810 g Na₂C₂O₄
And then I’m stuck…
4. Compare your experimentally determined % oxalate in your product to theoretically mass percentage of C₂O₄²¯ in K₃[Fe(C₂O₄)₃]∙3H₂O. Use the following equation to aid in your discussion: Experimentally determined % oxalate / Theoretically determined % oxalate x 100%
This seems fairly straight forward if I could correctly figure out #3…however, what would my theoretical
mass percent composition come from? Is it from the 0.2349 g of Na₂C₂O₄?
I know I'm not suppose to post more than one question per post but they are all related and if I made a mistake in the previous one then I carry it forward to the next; so pardon my breach of protocol.