Intro to acids and bases (video) | Khan Academy

What is the Latin origin and meaning of the word acid?

The word acid originates from the Latin word acidus, which means sour.

According to primitive definitions, what are the characteristic taste and tactile properties of acids?

Acids are usually sour tasting and can be sticky.

According to primitive definitions, what are the characteristic taste and tactile properties of bases?

Bases are bitter tasting and quite slippery.

What is the Arrhenius model definition of an acid?

An acid is a substance that produces $H^+$ ions in aqueous solutions.

What is the Arrhenius model definition of a base?

A base is a substance that produces $OH^-$ ions in aqueous solutions.

What ions are produced when hydrochloric acid ($HCl$) dissociates in an aqueous medium?

It dissociates into $H^+$ ions and $Cl^-$ ions.

Why is acetic acid classified as an acid under the Arrhenius definition?

It yields $H^+$ ions when mixed in water.

Why is ammonia classified as a base despite lacking $OH$ in its chemical formula?

When added to water, ammonia increases the amount of $OH^-$ ions in the solution.

How do $H^+$ ions cause acids to corrode metals?

$H^+$ ions suck electrons from metals to form hydrogen gas, while the resulting positive metal ions bond with anions and dissolve in solution.

How do $OH^-$ ions in bases assist in cleaning grease and oil?

$OH^-$ ions attach to water-insoluble oil and grease, making them water soluble so they can be washed away.

What two products are formed in a neutralization reaction between an acid and a base?

An ionic salt and water ($H_2O$).

Why are neutralization reactions classified as exothermic?

Energy is released when the constituent ions and molecules stick to each other.

Why do both acidic and basic solutions conduct electricity?

They contain free ions in solution that function as electrolytes.

Which specific ions are responsible for the sour taste of acids and the bitter taste of bases?

$H^+$ ions cause the sour taste in acids, and $OH^-$ ions cause the bitter taste in bases.

From what organism are the dyes used to produce litmus solution extracted?

Lichens.

What color change occurs when an acid is added to a blue litmus solution?

The blue litmus solution turns red.

What color change occurs when a base is added to a red litmus solution?

The red litmus solution turns blue.

How is a strong acid defined in terms of molecular dissociation?

A strong acid undergoes $100\%$ dissociation into ions in aqueous solution.

How is a weak acid defined in terms of molecular dissociation?

A weak acid undergoes partial dissociation in solution, typically around $5\%$ to $$6\%$.

Which three strong acids are explicitly named in the lecture?

Hydrochloric acid, sulfuric acid, and nitric acid.

Which three weak acids are explicitly named in the lecture?

Citric acid, carbonic acid, and phosphoric acid.

What is the distinction between acid strength and acid concentration?

Strength is a measure of the percentage of dissociation ($100\%$ vs. partial), whereas concentration is the amount of acid molecules per unit volume.

What generic chemical equation represents the dissociation of a generic acid $HA$ in water?

$$HA \rightarrow H^+ + A^-$$

Which weak acids mentioned in the lecture are found in soft drinks?

Carbonic acid and phosphoric acid.

Why are concentrated strong acids exceptionally dangerous?

They combine $100\%$ dissociation with a high quantity of acid molecules per unit volume, creating a very high concentration of $H^+$ ions.