Final answer:
Compounds are ranked by strength based on the stability of their conjugate base, inductive effects, and bond strengths. HClO3 is the strongest acid, followed by H3PO4 then CH3PO3H2. For bases, OH¯ is the strongest base, followed by CF3S¯ then CH3S¯.
Step-by-step explanation:
To rank the compounds in order of decreasing acid strength you need to consider the stability of the conjugate bases, inductive effects, and bond strengths. For the given acids
H3PO4, CH3PO3H2, and HClO3,
we can use these factors.
HClO3 (chloric acid) is a strong acid as it has a high tendency to lose its proton due to the presence of electronegative oxygen atoms stabilizing the conjugate base through resonance.
H3PO4 (phosphoric acid) is a moderately strong acid. It can donate protons from three hydroxy groups, but the conjugate base isn't as stable as the one resulting from HClO3.
CH3PO3H2 (methylphosphonic acid) has a CH3 group that donates electron density towards the phosphorus, making it less likely to lose a proton compared to H3PO4, hence it is the weakest of the three acids listed.
When comparing the base strength of
CH3S¯, OH¯, and CF3S¯,
the base strength is influenced by the ability to accept protons.
The OH¯ (hydroxide ion) is very basic as it readily accepts protons.
CF3S¯ (trifluoromethane thiolate) is less basic than OH¯ since the electronegative fluorine atoms pull electron density away from the sulfur atom, making it less nucleophilic.
CH3S¯ (methanethiolate) is the least basic among these since it lacks the strong electron-withdrawing groups that CF3S¯ has, making it less eager to accept protons compared to CF3S¯ and OH¯.