1. Consider the following three statements about neutralisation reactions: I. A neutralisation reaction is a reaction between an acid and a base II. At the equivalence point of a neutralisation reaction the pH of the resulting solution will be 7 III. Salts are obtained from neutralisation reactions. Which statement or combination of statements is always correct? A. Only I and II B. Only I C. I, II and III D. Only I and III 2. Which of the following aqueous solutions has the highest [OH-]? A. pure water B. a 1 × 10-3 M solution of NH4Cl C. a solution with a pOH of 12.0 D. a solution with a pH of 3.0 E. a 1 × 10-4 M solution of HNO3 3. A is a weak acid. Which equilibrium corresponds to the equilibrium constant Kb for A-? A. HA (aq) + H2O (l) ---> H2A+ (aq) + OH- (aq) B. A- (aq) + H3O+ (aq) ---> HA (aq) + H2O (l) C. A- (aq) + H2O (l) ---> HA (aq) + OH- (aq) D. HA (aq) + OH- (aq) ---> H2O (l) + H+ (aq)
Ionic Equilibrium
Chemical equilibrium and ionic equilibrium are two major concepts in chemistry. Ionic equilibrium deals with the equilibrium involved in an ionization process while chemical equilibrium deals with the equilibrium during a chemical change. Ionic equilibrium is established between the ions and unionized species in a system. Understanding the concept of ionic equilibrium is very important to answer the questions related to certain chemical reactions in chemistry.
Arrhenius Acid
Arrhenius acid act as a good electrolyte as it dissociates to its respective ions in the aqueous solutions. Keeping it similar to the general acid properties, Arrhenius acid also neutralizes bases and turns litmus paper into red.
Bronsted Lowry Base In Inorganic Chemistry
Bronsted-Lowry base in inorganic chemistry is any chemical substance that can accept a proton from the other chemical substance it is reacting with.
1. Consider the following three statements about neutralisation reactions:
I. A neutralisation reaction is a reaction between an acid and a base
II. At the equivalence point of a neutralisation reaction the pH of the resulting solution will be 7
III. Salts are obtained from neutralisation reactions.
Which statement or combination of statements is always correct?
- A.
Only I and II
- B.
Only I
- C.
I, II and III
- D.
Only I and III
2.
Which of the following aqueous solutions has the highest [OH-]?
- A. pure water
- B.
a 1 × 10-3 M solution of NH4Cl
- C.
a solution with a pOH of 12.0
- D.
a solution with a pH of 3.0
- E.
a 1 × 10-4 M solution of HNO3
3.
A is a weak acid. Which equilibrium corresponds to the equilibrium constant Kb for A-?
- A.
HA (aq) + H2O (l) ---> H2A+ (aq) + OH- (aq)
- B.
A- (aq) + H3O+ (aq) ---> HA (aq) + H2O (l)
- C.
A- (aq) + H2O (l) ---> HA (aq) + OH- (aq)
- D.
HA (aq) + OH- (aq) ---> H2O (l) + H+ (aq)
1)
- A neutralization reaction always defines the reaction between an acid(strong/weak) and a base(strong/weak).
- In neutralization reaction an acid and base react to form a salt and water. This salt is neutral, neither acidic nor basic.
- At equivalence point of any neutralization reaction between a strong acid and a strong base [H+] = [OH-], therefore pH of the solution is 7. When a reaction occurs between a strong acid and weak base, then at equivalence point [H+]> [OH-], so pH< 7. When a reaction occurs between a weak acid and strong base, then at equivalence point [H+]< [OH-], so pH>7. So, at equivalence point pH is not 7 all the time.
Therefore D) Only I and III is correct.
2)
- In pure water at room temperature, [H+] = [OH-]. And, kw (ionic product constant) = [H+] x [OH-] = 1x10-14
As [H+] = [OH-] = 10-7 M.
- 1 × 10-3 M solution of NH4Cl: NH4+ + H2O NH4OH + H+ this is the reaction between a strong acid (NH4+) and a weak base (NH4OH). NH4OH being a weak base can't dissociate too much to form OH- . But NH4+ liberates H+ to a greater extent. Therefore, in the resulting solution [H+] > [OH-]
Here pH= 7- 1/2 pkb - 1/2 log C
= 7- 1/2 {-log(1.8x10-5)} - 1/2 log(1x10-3) kb of NH3 = 1.8x 10-5
=7- 1/2x 4.744 + 1/2 x 3
=6.128
pOH = 14-6.128 = 7.872
So, pOH = -log[OH-}
[OH-] = 1.34x 10-8 M
- a solution with a pOH of 12.0: therefore, [OH-] = 10-pOH = 10 -12 M
- a solution with a pH of 3.0: pOH = 14- pH = 14- 3 = 11. So, [OH-] = 10-11 M
- a 1 × 10-4 M solution of HNO3 : pH = -log[H+] = -log[10-4] = 4
pOH = 14-pH = 14-4 = 10
[OH-] = 10-10 M
Option B. a 1 × 10-3 M solution of NH4Cl has highest [OH-]
Step by step
Solved in 2 steps
