In a lava lamp, a waxy substance rises and falls repeatedly. What causes the waxy substance to rise? Check all that apply.
2 answers:
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Answer:
The temperature at which the reaction changes from non-spontaneous to spontaneous is 588.735 K
Explanation:
The spontaneity of a reaction is determined by the change in Gibbs Free Energy, .
If is greater than zero, then a reaction is feasible.
If is less than zero, then a reaction is not feasible.
To determine the temperature at which the reaction changes from non-spontaneous to spontaneous, we should equate the to zero.
We take as the limiting condition.
Therefore, the temperature is: 588.735K
Answer:
2,4,6-tri-tert-butylcyclohexa-2,5-dienone
Explanation:
1. Information from the formulas
C₁₈H₃₀O ⟶ C₁₈H₂₉BrO
A Br has replaced an H.
2. Information from the reaction
These look like the conditions for an electrophilic aromatic substitution.
3. Possible mechanism (Fig. 1)
The product must be highly symmetrical, because there are so few NMR signals.
(i) The bromonium ion attacks at the para position, forming a resonance-stabilized carbocation intermediate.
(ii) A bromide ion attacks the H of the hydroxyl group to form 2,4,6-tri-tert-butylcyclohexa-2,5-dienone.
4. Confirmatory evidence (Fig. 2)
(a) Infrared
1630 cm⁻¹: C=O stretch
1655 cm⁻¹ : C=C stretch
(b)NMR
1.2 (9h, s): the 4-tert-butyl group
1.3 (18H, s): the 2- and 6- tert- butyl groups
6.9 (2H, s): the alkene H atoms
The ratio is 9:18:2.
