Acids, Bases and Salts Lecture Notes

Practice flashcards covering the properties of acids, bases, and salts, including chemical reactions, pH scales, and common chemical compounds.

What color does phenolphthalein turn in a basic solution like $NaOH$?

Pink

What are olfactory indicators?

Substances whose odour changes in acidic or basic media, such as onion, vanilla, and clove.

Write the balanced chemical equation for the reaction of zinc granules with sodium hydroxide.

$2NaOH(aq) + Zn(s) \rightarrow Na_2ZnO_2(s) + H_2(g)$, where $Na_2ZnO_2$ is sodium zincate.

What are the products when a metal carbonate or metal hydrogencarbonate reacts with an acid?

Salt, carbon dioxide, and water.

What is the chemical equation for the reaction of sodium carbonate with hydrochloric acid?

$$Na_2CO_3(s) + 2HCl(aq) \rightarrow 2NaCl(aq) + H_2O(l) + CO_2(g)$$

What is the result of passing excess carbon dioxide through lime water?

The white precipitate dissolves to form calcium hydrogencarbonate ($Ca(HCO_3)_2$), which is soluble in water.

What is a neutralization reaction?

The reaction between an acid and a base to give a salt and water: $\text{Base} + \text{Acid} \rightarrow \text{Salt} + \text{Water}$.

Why are metallic oxides classified as basic oxides?

Because they react with acids to produce salt and water, similar to the reaction of a base with an acid.

What is the nature of non-metallic oxides?

Non-metallic oxides are acidic in nature because they react with bases to produce salt and water.

Why do glucose and alcohol solutions not conduct electricity, while acidic solutions do?

Acidic solutions produce ions ($H^+$) that carry electric current, whereas glucose and alcohol do not produce ions in solution.

Which ion is responsible for the acidic properties of a substance in solution?

The hydrogen ion, $H^+(aq)$, or hydronium ion, $H_3O^+$.

What is an alkali?

A base that dissolves in water.

What defines the process of dilution?

Mixing an acid or base with water, which results in a decrease in the concentration of ions ($H_3O^+/OH^-$) per unit volume.

Why must acid be added to water slowly with constant stirring during dilution?

The process is highly exothermic; adding water to concentrated acid can generate enough heat to cause the mixture to splash out or break the glass container.

What does the 'p' in pH stand for, and what is its meaning?

It stands for 'potenz' in German, meaning power.

What is the pH range of a neutral solution?

$$7$$

What is the relationship between hydronium ion concentration and pH value?

The higher the hydronium ion concentration, the lower the pH value.

What is the functional pH range of the human body?

$7.0$ to $7.8$

What is the pH threshold for rain to be considered 'acid rain'?

A pH less than $5.6$

What substance is commonly used as an antacid to neutralize excess stomach acid?

Magnesium hydroxide ($\text{Milk of magnesia}$), which is a mild base.

At what pH level does tooth decay typically begin?

When the pH of the mouth is lower than $5.5$

What acid is present in a bee-sting or nettle-sting?

Methanoic acid.

Name the naturally occurring acids found in vinegar and tamarind.

Acetic acid (vinegar) and Tartaric acid (tamarind).

How are the pH values of salts derived from strong acids and weak bases characterized?

They are acidic with a pH value less than $7$

What are the three primary products of the chlor-alkali process?

Sodium hydroxide ($NaOH$), chlorine ($Cl_2$), and hydrogen ($H_2$).

What is the chemical formula for bleaching powder?

$$Ca(ClO)_2$$

How is baking soda ($NaHCO_3$) produced?

By reacting sodium chloride, water, carbon dioxide, and ammonia ($NH_3$).

What is the chemical formula for washing soda?

$$Na_2CO_3 \cdot 10H_2O$$

Define 'water of crystallisation'.

The fixed number of water molecules present in one formula unit of a salt.

What is the chemical formula for Gypsum?

$$CaSO_4 \cdot 2H_2O$$

What is the chemical name and formula for Plaster of Paris?

Calcium sulphate hemihydrate, $CaSO_4 \cdot \frac{1}{2}H_2O$

What happens to Plaster of Paris when it is mixed with water?

It changes back into gypsum, forming a hard solid mass.