Acid, Base and Salts RRB PYQ

When a small amount of acid is added to water, both ionization and dilution occur. Ionization involves the dissociation of the acid into hydrogen ions (H+) and conjugate base ions in water, making the solution acidic. Dilution refers to the process where the addition of acid to water results in a decrease in the concentration of the acid, spreading it out in a larger volume of water.

NaCl is formed by the reaction of HCl and NaOH. HCl is a strong acid and NaOH is a strong base; NaCl is therefore a neutral salt. When a strong acid and a strong base react together, the resultant is salt and water.

pH = pKa + log([A-]/[HA]) = 4.76 + log(0.1/0.1) = 4.76 + log(1) = 4.76.

pH is a measure of the hydrogen ion concentration of a solution. The pH scale ranges from 0 to 14, with 7 being neutral. A pH value greater than 7 indicates a basic solution, while a pH value less than 7 indicates an acidic solution. A solution with a pH of 12 is highly basic. In a basic solution, the concentration of OH- ions is higher than the concentration of H+ ions.

When hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), it is called a neutralisation reaction. The products formed are sodium chloride (NaCl), which is common salt, and water (H2O). The chemical equation is: HCl + NaOH → NaCl + H2O. A neutralisation reaction is a reaction in which an acid reacts with a base to form salt and water. It is usually exothermic as heat is released.

In acidic solutions, phenolphthalein is colourless. It acts as a pH indicator and remains colorless in acidic and neutral environments. As the solution becomes basic or alkaline, phenolphthalein changes color to pink. This property makes it useful for titrations to determine the endpoint of a reaction.

The pH range is from 0 to 14, with 7.0 being neutral. Anything above 7.0 is alkaline, anything below 7.0 is considered acidic. The human body works within the pH range of 7.0 to 7.8.

If HF is a weak acid, its conjugate base F- is a weak base. If HF (hydrofluoric acid) is a weak acid, it means it does not dissociate completely in water. However, in the context of acid-base theory, a strong acid has a very weak conjugate base and a weak acid has a stronger conjugate base. So, while F- is stronger than the conjugate base of a strong acid, it is still not a strong base like OH- or O2-. It's classified as a weak base.

Acids show their acidic nature because they release hydrogen ions (H+) when mixed with water. These H+ ions are what make a solution acidic. The more H+ ions there are in a solution, the stronger the acid is. H+ ions are also called protons, and they can join with water molecules to form hydronium ions (H3O+). We use the pH scale to measure how acidic or basic a solution is. A lower pH means there are more H+ ions, which means the solution is more acidic.

Washing soda (Na2CO3·10H2O) is obtained from sodium bicarbonate in the Solvay process. Sodium bicarbonate is then heated to form sodium carbonate (Na2CO3), which is converted to washing soda by adding water of crystallization. In the Solvay process, sodium carbonate is produced using sodium chloride and limestone. Washing soda is a crystalline, white, water-soluble solid that has many household and industrial uses.