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CHEM 20 QUESTION: Is there a test to determine if a chemical reaction is complete?
I'm doing a mock lab and it asks what test I could take to ensure that the chemical reaction between Pb(NO3)2 + 2 KI has completed.
Thank you.
3 Answers
- Anonymous9 years agoFavorite Answer
No reaction completes completely. But, first calculate and then observe the volume reacted and obtained by the help of number of moles and molecular masses shown in the rxn.
- 9 years ago
I'm not familiar with this reaction but it looks like you are going to form PbI2 salt precipitate.
You will either (mostly) run out of Pb or (mostly) run out of I
If you run out of iodide, there might be a color change.
Also when it's done reacting, the precipitate will stop forming. The solution will always be in equilibrium though. The solubility of lead iodide is highly temperature dependent. So it will re-dissolve if heated.
- John WLv 79 years ago
PbI2(s) is yellow. When it stops forming you have equal amounts of KNO3 which due to hydrolysis would be neutral. (KOH + HNO3)
Pb(NO3)2(aq) would be acidic due to the NO3 -(aq) ion inm water. If you check the pH as you go along precipitation should end at pH 7.
Source(s): Teacher