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1. Label each of the following as Arrhenius acid, Arrhenius base, salt, or molec

ID: 1006070 • Letter: 1

Question

1. Label each of the following as Arrhenius acid, Arrhenius base, salt, or molecular compound.

HCl

NaOH

HC2H3O2

MgCl2

H2O

CCl4

Mg(OH)2

2. Which of the following could be considered Brønsted bases.

NH3

NaOH

CH4

CH3CH2COOH

Cl-

CH3NH2

5. Determine the conjugate acid–base pairs in the following equations:

HBr(aq) + H2O(l) H3O+(aq) + Br(aq)

CH3NH2(aq) + H2O(l) CH3NH3+(aq) + OH(aq)

10. The [H3O+] of tomato juice is 2.2 x 104 M. What is the pH of the solution?

14. Calculate the pOH of a solution that has a pH of 8.35.

16. Calculate the pH of a solution with [OH] of 4.0 x 105 M.

18. Which combination makes a buffer solution?   

HBr and KBr

H3PO4 and KH2PO4

HCOOH and LiHCOO

HNO2 and NaNO3

22. Write the net ionic equation for the reaction of perchloric acid with barium hydroxide.

Explanation / Answer

Q.1: An Arrhenius acid is a compound that gives H+ ion in water. An Arrhenius base is a compound that gives OH- ion in water.

A salt is fomed by the neutralization reaction of an acid and a base.

HCl: HCl gives H+ ion in water. Hence it is an Arrhenius acid.

NaOH: NaOH gives OH- ion in water. Hence it  is an Arrhenius base.

HC2H3O2: HC2H3O2 gives H+ ion  in water. Hence it is an Arrhenius acid.

MgCl2: MgCl2 is formed by the neutralization reaction of acid and base. Hence it is a salt.

H2O and CCl4 are molecular compounds.

Mg(OH)2  gives OH- ion in water. Hence it  is an Arrhenius base.

Q.2: Bronsted bases are NH3, NaOH and CH3NH2

Q.5: a) HBr(aq) + H2O(l) H3O+(aq) + Br(aq)

conjugate acid–base pairs: HBr and Br-(aq)

H2O(l) and H3O+

(b): CH3NH2(aq) + H2O(l) CH3NH3+(aq) + OH(aq)

conjugate acid–base pairs: CH3NH2(aq) and CH3NH3+(aq)

H2O(l) and OH(aq)

Q.10: pH = - log[H3O+] = - log(2.2x10-4 M) = 3.66 (answer)

Q.14:pH + pOH = 14

=> pOH = 14 - pH = 14 - 8.35 = 5.65 (answer)

Q.16: pOH =  - log[OH-] = - log(4.0x10-5 M) = 4.40

pH = 14 - pOH = 14 - 4.40 = 9.60 (answer)

Q.18: HCOOH and LiHCOO will form a buffer solution.