Which of the following substances is an acid? (Select all that apply)
a
NaOH
b
HCl
c
KOH
d
H2S
b
HCl
The substances that are acids are:
- HCl (hydrochloric acid)
- H2S (hydrosulfuric acid)
To determine which substances are acids, we need to understand their properties.
An acid is a substance that donates hydrogen ions (H+) when dissolved in water. It has a sour taste, turns blue litmus paper red, and can react with metals to produce hydrogen gas.
Now let's analyze the given substances:
a) NaOH: Sodium hydroxide (NaOH) is a base, not an acid. It is a strong base that dissociates into hydroxide ions (OH-) when dissolved in water.
b) HCl: Hydrochloric acid (HCl) is an acid. It dissolves in water to form hydrogen ions (H+) and chloride ions (Cl-). It is a strong acid commonly found in stomach acid.
c) KOH: Potassium hydroxide (KOH) is a base, not an acid. Similar to NaOH, it dissociates into hydroxide ions (OH-) when dissolved in water.
d) H2S: Hydrogen sulfide (H2S) is not an acid. It is a gas with a characteristic smell of rotten eggs. It does not readily dissociate into ions when dissolved in water.
Based on the above analysis, the substances that are acids are:
- HCl
So, the correct answer is:
- b) HCl