the pka of acetone is CH3COCH3 is 19.3 which of these bases is strong enough to deprotonate acetone?
a)KOH (pka of H20 = 15.7)
b)Na+ -C(triplebond)CH (pka of C2H2 = 25)
c)NaHCO3 (pka of H2CO3 = 6.4)
d)NaOCH3 pka of CH3OH = 15.6)
i know the answer is b but why is it b? is it because the pka is high?
To determine which base is strong enough to deprotonate acetone (CH3COCH3), we need to compare the pKa values of the bases with the pKa value of acetone.
The pKa value represents the acidity constant of a compound. The lower the pKa value, the stronger the acid. In this case, we are looking for a base that has a higher pKa value than acetone (pKa=19.3) because a higher pKa value indicates a weaker acid.
Let's analyze each option:
a) KOH (pKa of H2O = 15.7):
The pKa of water is lower than acetone's pKa, which means water is a stronger acid than acetone. Hence, KOH is not strong enough to deprotonate acetone.
b) Na+ -C≡CH (pKa of C2H2 = 25):
The pKa of acetylene (C2H2) is higher than acetone's pKa, which means acetylene is a weaker acid than acetone. Therefore, Na+-C≡CH is strong enough to deprotonate acetone.
c) NaHCO3 (pKa of H2CO3 = 6.4):
The pKa of carbonic acid (H2CO3) is significantly lower than acetone's pKa, indicating that carbonic acid is a much stronger acid. Thus, NaHCO3 is not strong enough to deprotonate acetone.
d) NaOCH3 (pKa of CH3OH = 15.6):
The pKa of methanol (CH3OH) is comparable to the pKa of acetone. Similar pKa values suggest similar strengths, so NaOCH3 may not be strong enough to deprotonate acetone.
By analyzing the pKa values, we find that only option (b) Na+ -C≡CH has a higher pKa value than acetone. Therefore, option (b) is the correct answer, and it is because its pKa is higher than acetone's pKa.
N2O4(g) 2 NO2(g)
The ΔH° for the reaction above is +57.2 kJ. The system is initially at equilibrium. Which of the following changes will favor the reverse reaction?
NO2 is removed.
N2O4 is removed.
A catalyst is added.
The temperature is increased.
The temperature is decreased.
The volume of the container is increased.
The volume of the container is decreased.
Ar is added at constant pressure.
Ar is added at constant volume.