Upon attempt, I've yielded an answer of 11.91g. My calculations do not take 300 mL Lactic acid solution into account, and now I somewhat know the error is at least partially due to the fact that my working out is independent on the the quantity of solution. All help is highly appreciated.
Here is my working out:
my molar mass of potassium lactate is incorrect in the final step, none the less the answer is still incorrect.
For those who will ask, the answer is 12.6 g