Worksheet: Acid and Base Strengths

In this worksheet, we will practice defining the strength of an acid or base and describing the relationships between pH, pOH, pKa, and pKb.

Q1:

Of the following ions, which is the strongest Brønsted–Lowry base?

  • A C l
  • B H S O 4
  • C F
  • D B r
  • E N O 3

Q2:

Which one out of HOCl, HOClO, HOClO2, and HOClO3 is the strongest acid?

  • A H O C l O
  • B H O C l
  • C H O C l O 2
  • D H O C l O 3
  • EThey are all equally strong acids.

Q3:

Of the compounds HOCl, HOBr, and HOI, which is the strongest acid?

  • A H O I
  • B H O B r
  • C H O C l
  • DThey are all equally strong acids.

Q4:

Which one out of BrO2, ClO2, and IO2 is the strongest base?

  • A B r O 2
  • B I O 2
  • C C l O 2
  • DThey are all equally strong bases.

Q5:

Which one out of BrO, BrO2, BrO3, and BrO4 is the strongest base?

  • A B r O 4
  • B B r O
  • C B r O 3
  • D B r O 2

Q6:

Which one out of NH2, HS, HTe, and PH2 is the strongest base?

  • A P H 2
  • BThey are all equally strong.
  • C H S
  • D N H 2
  • E H T e

Q7:

Which conjugate acid, (CH)NH322+ or (CH)NH323+, is the stronger acid at 25C? 𝐾=4.4×10b32(CHNH) and 𝐾=5.9×10b32((CH)NH).

  • A ( C H ) N H 3 2 2 +
  • BThey are both ammonium ions, and therefore, they are equally strong acids.
  • CIt is impossible to tell without knowing at what concentrations the acidities of the compounds are measured.
  • D ( C H ) N H 3 2 3 +

Q8:

A solution has a HCl concentration of 0.10 M and a formic acid (HCOOH) concentration of 0.10 M. Why is the hydronium ion concentration in this solution mainly determined by the concentration of HCl?

  • A H C O O H does not dissociate at all, so HCl is the only contributor to [H]+.
  • B H C l reacts with HCOOH, neutralizing it.
  • C H C O O H dissociates to form both hydroxide and hydronium ions, so it has no net effect on [H]+.
  • D H C l dissociates completely, while HCOOH only partially dissociates.

Q9:

Aniline (CHNH)652 is a much weaker base than ammonia (NH)3. If the initial concentrations of ammonia and aniline in a solution are both equal to 0.10 M, which of the following statements is true at equilibrium?

  • A [ O H ] = [ C H N H ] 6 5 2
  • B [ O H ] = [ N H ] 4 +
  • C [ N H ] = [ C H N H ] 3 6 5 2
  • D [ N H ] = [ C H N H ] 4 + 6 5 3 +
  • E [ O H ] = [ C H N H ] 6 5 3 +

Q10:

Which one out of NaHSO3, NaHSeO3, and NaHSO4 is the strongest acid?

  • AThey are all salts and therefore are not acidic.
  • B N a H S e O 3
  • C N a H S O 4
  • DThey are all equally strong acids.
  • E N a H S O 3

Q11:

Place the compounds HCl, PH3, and SH2 in order of increasing acid strength.

  • A P H 3 , H C l , S H 2
  • B H C l , S H 2 , P H 3
  • C P H 3 , S H 2 , H C l
  • D H C l , P H 3 , S H 2
  • E S H 2 , P H 3 , H C l

Q12:

Why is the ionization constant, 𝐾a, for HSO24 larger than the ionization constant for HSO23?

  • AThe OH bonds in HSO24 are more easily broken because the bonding electrons are delocalised over more oxygen atoms.
  • BThe OH bonds in HSO24 are less easily broken because the bonding electrons are delocalised over more oxygen atoms.
  • CThe protons of HSO24 are more easily removed because they are bonded to a larger number of oxygen atoms.
  • DThe conjugate base of HSO24 is less easily protonated because the negative charge is delocalized over more oxygen atoms.
  • EThe conjugate base of HSO24 is more easily protonated because the negative charge is delocalized over more oxygen atoms.

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