Worksheet: Conjugate Acid–Base Pairs

In this worksheet, we will practice identifying conjugate acids and bases in chemical equations and predicting their relative acid or base strengths.

Q1:

In the equation shown, NH3 is the conjugate acid. What is the missing term? NH()+HO+HO323+aq

  • ANH24
  • BNH4+
  • CNH2
  • DNH3

Q2:

Give the formula and state the symbol of the missing compound in the given equation. HSO()+OH()+HO()32aqaql

  • ASO()32aq
  • BSO()2g
  • CHSO()24aq
  • DHSO()23aq
  • EHS()2g

Q3:

In the given equation, HPO24 is the conjugate base. What is the missing term? HPO+HO+OH242

  • AHPO23+
  • BHPO34
  • CHPO24
  • DPO43
  • EHPO42

Q4:

What is the conjugate acid of OH?

  • AHO2
  • BHO22
  • CHO3+
  • DO2

Q5:

What is the conjugate acid of HO2?

  • AO2
  • BHO22
  • CHO3+
  • DOH

Q6:

What is the conjugate acid of HS?

  • AS2
  • BSO2
  • CHS2

Q7:

In the equation shown, NH3 is the conjugate base. What is the missing term? NH()+HO+OH32aq

  • ANH3
  • BNH24
  • CNH2
  • DNH4+

Q8:

HSO24 and Cl ions react according to the equation shown. HSO+ClHCl+HSO244

Which species is the Brønsted–Lowry acid in this reaction?

  • AHCl
  • BHSO24
  • CCl
  • DHSO4

Which species is the conjugate base of the Brønsted–Lowry acid in this reaction?

  • AHSO4
  • BHSO24
  • CCl
  • DHCl

Which species is the Brønsted–Lowry base in this reaction?

  • AHCl
  • BHSO24
  • CHSO4
  • DCl

Which species is the conjugate acid of the Brønsted–Lowry base in this reaction?

  • AHCl
  • BHSO4
  • CHSO24
  • DCl

Q9:

Consider the reaction shown and then answer the following questions. HSO+OHSO+HO4422

Which species is a Brønsted–Lowry acid?

  • AHO2
  • BSO42
  • CHSO4
  • DOH

Which species is the conjugate base of a Brønsted–Lowry acid?

  • AHO2
  • BHSO4
  • COH
  • DSO42

Which species is a Brønsted–Lowry base?

  • AHSO4
  • BHO2
  • CSO42
  • DOH

Which species is the conjugate acid of a Brønsted–Lowry base?

  • AHSO4
  • BOH
  • CHO2
  • DSO42

Q10:

Two aqueous complex ions react according to the equation shown. [Cu(HO)(OH)]+[Al(HO)][Cu(HO)]+[Al(HO)(OH)]25+263+262+252+

Which species is the Brønsted–Lowry acid in this reaction?

  • A[Al(HO)(OH)]252+
  • B[Cu(HO)(OH)]25+
  • C[Al(HO)]263+
  • D[Cu(HO)]262+

Which species is the conjugate base of the Brønsted–Lowry acid in this reaction?

  • A[Cu(HO)(OH)]25+
  • B[Al(HO)(OH)]252+
  • C[Al(HO)]263+
  • D[Cu(HO)]262+

Which species is the Brønsted–Lowry base in this reaction?

  • A[Al(HO)(OH)]252+
  • B[Al(HO)]263+
  • C[Cu(HO)(OH)]25+
  • D[Cu(HO)]262+

Which species is the conjugate acid of the Brønsted–Lowry base in this reaction?

  • A[Al(HO)(OH)]252+
  • B[Cu(HO)(OH)]25+
  • C[Al(HO)]263+
  • D[Cu(HO)]262+

Q11:

For the reaction of mercury(II) chloride and ammonia, which product is a conjugate Lewis base?

  • ANH3
  • BHg(NH)32
  • CHgCl2
  • DCl

Q12:

Gastric juice, the digestive fluid produced in the stomach, contains hydrochloric acid, HCl. Milk of magnesia, a suspension of solid Mg(OH)2 in an aqueous medium, is sometimes used to neutralize excess stomach acid. 𝑥HCl()+Mg(OH)()Mg()+2Cl()+2HO()aqaqaqaql22+2

What value of 𝑥 produces a balanced chemical equation?

What is the conjugate acid of Mg(OH)2?

  • ACl
  • BHO2
  • CHCl
  • DMg2+
  • EMgCl2

Q13:

Why does the complete reaction of a weak acid with a strong base produce a basic solution?

  • AAn excess of strong base must be used for the reaction to reach completion.
  • BThe reaction produces a weak conjugate base and no conjugate acid.
  • CThe reaction produces a strong conjugate base and a weak conjugate acid.
  • DThe reaction produces ions that interact strongly with hydroxide ions in solution, stabilizing their negative charge.
  • EWater competes with the weak acid to react with the base, raising the concentration of hydroxide ions.

Q14:

What is the conjugate base of HN52+?

  • AHN622+
  • BHN22
  • CHN42

Q15:

What is the conjugate acid of HCO3?

  • ACO2
  • BHCO23
  • CCO32

Q16:

What is the conjugate base of HO22?

  • AHO3+
  • BHO2
  • CHO2
  • DHO32+

Q17:

In the shown equation, NH3 is the conjugate base. What is the missing term? NH()+HO+OH32aq

  • ANH3
  • BNH24
  • CNH4+
  • DNH2

Q18:

What is the conjugate base of HSO4?

  • AHS2
  • BSO2
  • CSO42
  • DHSO24

Q19:

Consider the reaction shown. HS+NHHS+NH223

Which species is a Brønsted–Lowry acid?

  • ANH2
  • BHS2
  • CHS
  • DNH3

Which species is the conjugate base of a Brønsted–Lowry acid?

  • ANH2
  • BHS
  • CHS2
  • DNH3

Which species is a Brønsted–Lowry base?

  • AHS2
  • BNH3
  • CHS
  • DNH2

Which species is the conjugate acid of a Brønsted–Lowry base?

  • ANH2
  • BHS
  • CNH3
  • DHS2

Q20:

What is the conjugate acid of NH3?

  • AHO3+
  • BNH4+
  • CNH22
  • DOH
  • ENH2

Q21:

What is the conjugate base of OH?

  • AO2
  • BHO3+
  • CHO2
  • DH+

Q22:

What is the conjugate base of HS?

  • AHS2
  • BSO2
  • CS2

Q23:

In the shown equation, HPO24 is the conjugate acid. What is the missing term? HPO+HO+HO2423+

  • AHPO23+
  • BHPO24
  • CHPO34
  • DHPO42
  • EPO43

Q24:

What is the conjugate acid of HN52+?

  • AHN42+
  • BHN52
  • CHN62+
  • DHN622+
  • EHN42

Q25:

What is the conjugate base of HCO3?

  • AHCO23
  • BCO32
  • CCO2

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