Deduce Bronsted-Lowry Base
Let's take a look at our discussion question this week!
We want to determine if the underlined species are acting as Bronsted-Lowry bases.
Let us first understand what is an acid and base according to the Bronsted-Lowry theory.
Bronsted acid is a proton (H+) donor.
Bronsted base is a proton (H+) acceptor.
The biggest difference between Bronsted-Lowry theory and Arrhenius theory is in the base.
Arrhenius base must dissolve in water to give OH-, while Bronsted base just need to accept H+.
Check out this video lesson for a detailed comparison of the 3 different acid-base theories.
Let's look at the 3 options and determine the Bronsted acid and base.
NH4+ donates proton to form NH3, hence NH4+ is the Bronsted acid.
Underlined species H2O accepts proton to form H3O+, hence H2O is the Bronsted base.
Hence option 1 is correct.
H2SO4 donates proton to form HSO4-, hence H2SO4 is the Bronsted acid.
Underlined species HNO3 accepts proton to form H2NO3+, hence HNO3 is the Bronsted base.
Hence option 2 is correct.
It will be easier to deduce the acid and base if we separate NaNH2 into Na+ and NH2-.
CH3COCH3 donates proton to form CH3COCH2-, hence CH3COCH3 is the Bronsted acid.
Underlined species NH2- accepts proton to form NH3, hence NH2- is the Bronsted base.
Hence option 3 is correct.
Therefore all options are correct and the answer to this question is option D.
Topic: Ionic Equilibria, Physical Chemistry, A Level Chemistry, Singapore
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