Question

A. What was the pH change when HCI was added to tap water?

Answer 1

Answer:

A)

Solution:

Adding a strong acid such as HCl to water results in the release of H+ ions.  

Arrhenius Theory: An acid is a substance which produces one or more hydrogen ions, (H+) in aqueous solution.

Examples:

$HCl(aq)>(aq)H^+Cl^-(aq)$

(H+) from the acid binds to neutral water molecules to form $H_3O^+$ raising the concentration of H+.  

The resulting large concentration of (H+) makes the solution more acidic and leads to a dramatic drop in the pH.

B)

Solution :

An acid is a substance which produces one or more hydrogen ions, (H+) in aqueous solution.

Examples:

$HCl(aq)>(aq)H^+Cl^-(aq)$

So, HCl is an acid.

C)

Solution :

A Base is a substance which produces one or more hydroxyl ion or hydroxide ion (OH-) in aqueous solution.

Examples :

$KOH(s)> K^+(aq) +OH^-(aq)\\\\Ca(OH)_2(s)>Ca^{2+}(aq) +2OH^- (aq)\\\\Al(OH)_3(s)> Al^{3+}(aq)+ 3OH^- (aq)$

Please note: (aq) stands for aqueous which means in the presence of water that is, water acts as a solvent

The release of OH- ions makes the solution more basic and this leads to an increase in pH of the solution  

D)

Solution:

A Base is a substance which produces one or more hydroxyl ion or hydroxide ion (OH-) in aqueous solution.

Examples

$KOH(s)> K^+(aq) +OH^-(aq)\\\\Ca(OH)_2(s)>Ca^{2+}(aq) +2OH^- (aq)\\\\Al(OH)_3(s)> Al^{3+}(aq)+ 3OH^- (aq)$

Please note: (aq) stands for aqueous which means in the presence of water that is, water acts as a solvent

So, NaOH is a Base.

Answer 2

Answer:

See below.

Explanation:

a. The pH would decrease.

b. An acid.

c. The pH would increase.

d. A base.  More accurately an alkali ( which is a soluble base).