What makes a compound a base?
a
It dissolves into Hydrogen ions in water (H+ or H3O+)
b
It has a pH lower than 7
c
It dissolves into Hydroxide ions in water (OH-)
d
It cannot be mixed with oil
c
It dissolves into Hydroxide ions in water (OH-)
The correct answer is c: It dissolves into Hydroxide ions in water (OH-).
A compound is considered a base if it dissociates or ionizes in water to release hydroxide ions (OH-) into the solution. When the base is dissolved in water, it forms hydroxide ions, which can accept protons (H+) to form water molecules (H2O).
Option a is incorrect because compounds that dissolve into hydrogen ions in water are acidic, not basic. These compounds are known as acids.
Option b is also incorrect because the pH scale ranges from 0 to 14, and compounds with a pH lower than 7 are considered acidic, not basic.
Option d is unrelated to the definition of a base. Being miscible or immiscible with oil does not determine whether a compound is a base or not.
The correct answer is c) It dissolves into Hydroxide ions in water (OH-).
To determine what makes a compound a base, you need to understand the concept of acids and bases. Acids are substances that release hydrogen ions (H+) or hydronium ions (H3O+) when dissolved in water, while bases are substances that release hydroxide ions (OH-) when dissolved in water.
Option a) - It dissolves into Hydrogen ions in water (H+ or H3O+): This characteristic actually describes an acid rather than a base. Acids are the opposite of bases, as they release hydrogen ions in water.
Option b) - It has a pH lower than 7: The pH scale is used to indicate the acidity or alkalinity (basicity) of a substance. pH values below 7 are acidic, while pH values above 7 are alkaline or basic. Therefore, a substance with a pH lower than 7 is an acid, not a base.
Option c) - It dissolves into Hydroxide ions in water (OH-): This option correctly describes a base. When a compound dissolves in water and releases hydroxide ions (OH-), it is considered a base. Bases are also referred to as alkaline compounds.
Option d) - It cannot be mixed with oil: This characteristic does not determine whether a compound is an acid or a base. The ability to mix with oil or not is unrelated to the chemical properties of acids or bases.
In summary, a compound is considered a base if it dissolves into hydroxide ions (OH-) when mixed with water.