Is everything an acid or a base?
it totally depends.
It depends on how you define an acid and base. In water systems, yes. But in non water solutions...say oil mixed in gasoline....pH has no meaning.
Why acids act in similar ways?
Acids act in similar ways because they share some common properties and behaviors. These properties can be explained by the Arrhenius and Brønsted-Lowry theories of acids.
According to the Arrhenius theory, an acid is a substance that increases the concentration of hydrogen ions (H+) when dissolved in water. When acids dissolve in water, they donate protons (H+) to water molecules, resulting in an increase in the concentration of H+ ions. As a result, acids can exhibit common properties such as sour taste, ability to dissolve certain metals, and the ability to turn blue litmus paper red.
The Brønsted-Lowry theory expands on the concept of acids by defining them as proton (H+) donors. In this theory, acids are substances capable of donating a proton to another substance. This broader definition of acids allows for a better understanding of why acids exhibit similar behaviors.
In both theories, acids are known for their ability to react with bases to form water and a salt in a process called neutralization. This reaction occurs when the proton (H+) from the acid combines with the hydroxide ion (OH-) from the base to form water (H2O). The remaining ions combine to form a salt.
Overall, the similar behavior of acids can be attributed to their ability to donate protons, react with bases to form water and salt, and exhibit common properties such as sour taste and affecting the color of indicator dyes.