Phosphine (PH3) decomposes into phosphorus and molecular hydrogen: 4PH3(g) P4(g)
ID: 591477 • Letter: P
Question
Phosphine (PH3) decomposes into phosphorus and molecular hydrogen: 4PH3(g) P4(g) + 6H2(g) Experiments show that this is a first-order reaction, with a rate constant of 0.0173 s-1 at 650°C. Identify each of the following statements about this reaction as true or false. (Use the drop-down menu and select "True" or "False" for each. You must get all 4 correct.)
The reaction PH3 PH2 + H might be the rate-determining step in the mechanism of this reaction.
The rate constant would be greater than 0.0173 s-1 at 340°C.
The overall reaction could occur as a single elementary step.
The activation energy for the reaction cannot be determined without additional data.
Explanation / Answer
1. Yes this reaction will be rate determining reaction as it is the slowest reaction.
2. True. The rate constant will be greater. The rate constant increases with increase in temperature according to the arrhenious equation. K= A e^ (-Ea/RT)
3. FALSE. The overall reaction cannot occur as a single elementary step.
4. True. The activation energy cannot be determined without additional data. We just need the value of Arrhenious constant.