Discussion: 1. So two students in the lab forgot to heat up one of their samples
ID: 968173 • Letter: D
Question
Discussion:
1. So two students in the lab forgot to heat up one of their samples. When they started titrating it turned pink with 2.01 mL of KMnO4. They left the flask alone for a few minutes and then the pink color had gone away. They added more KMnO4 with the same result. So what purpose do you think heating the solution had on the reaction??
2. Using the chemical reaction in the introduction:
16 H+ + 5 C2O4-2 + 2 MnO4- -----> ? 10 CO2 + 2 Mn+2 + 8 H2O
a. What element is oxidized?
b. What element is reduced?
c. What element is the reducing agent?
d. What element is the oxidizing agent?
e. How many electrons are getting transferred?
1. Here is another titration curve:
b. so is the titrant being added a strong acid or strong base?
c. How many mL of the titrant was used to hit the equivalence point?
2. When you added acid into base in the Strong Acid/Base Lab, you used phenolphthalein to indicate the endpoint. How come we can use this indicator to determine the equivalence point, even though it technically turns pink above the equivalence point?
pH 10 20 30 40 50 60 70 80 90 Volume of titrant (mL)Explanation / Answer
(1) Heating the first solution allows more reactivity of that substance.
(2) (a) Carbon of oxalate ion is oxidised
(b) Manganese of permanganate ion is reduced
(c) Permanganate is oxidising agent
(d) Five electrons are transfered
(1) (A) Acid - base- titration curve
(b) Strong Acid
(c) 41 mL has been added approximately
(2)