Properties of Acids – Definition, Examples, Properties, Uses

Acids have a corrosive effect. When we cook acidic foods in brass or copper utensils, the metal reacts and corrodes. When copper reacts with acid, it creates copper salt. Copper salts are toxic and taint the flavour of cooked food. This is why we don’t keep liquid foods in metallic containers. Tea should also be served in copper mugs.

Tin, a brilliant white metal, is applied to metallic vessels composed of brass or copper. Tin is non-reactive to acids, therefore it protects against food poisoning. Stainless steel utensils are now often used in the kitchen. Robert Boyle (1627-1691) was the first to investigate acid characteristics, describing them as sour, caustic, and turning blue litmus red. In 1774, Lavoisier, a French chemist, discovered that some nonmetal oxides, when dissolved in water, create acids. As a result, he considered water to be a necessary component of an acid.

What is dilute acid?

Acids are divided as: Dilute acids and Concentrated acids based on their concentration. 

Dilute acids are a type of acid that contains a lot of water. They are concentrated in order to reduce the quantity of acid present. It eliminates the dangers of high-risk acids. 

It also concentrate on storing acids for everyday usage. They are also utilised to regulate a variety of chemical processes. Diluted acids are weaker in nature as the major constituent in them is water. These acids are mostly used in laboratories for carrying out basic experiments for study purposes.

Examples of Dilute Acids:

1. Hydrochloric acid is the most often used dilute acid. Because concentrated hydrochloric acid is extremely corrosive, it cannot be used on a regular basis. Diluted hydrochloric acid is utilised in a variety of applications, including surface cleaning, medicinal treatments, battery manufacturing, and so on. 
2. Diluted acetic acid is a typical household acid. It is used as a cleaning agent, in salads, in chemical synthesis, and other applications. Vinegar contains approximately 4% dilute acetic acid. 
3. Strong acids, such as citric and sulfuric acids, are usually used in diluted form to decrease the risk of handling them. These acids are diluted to a certain extent, especially when used for instructional reasons.

Properties of Diluted Acids

• Diluted acids have a sour flavour, although it is less sour than concentrated acids. You may test this by diluting vinegar with water and comparing the flavours of the original and diluted solutions.
• Even when dilute, acids may dissolve in water and conduct electricity. In water, they dissociate to form hydronium ions.
• Even when diluted, acids may be corrosive. It is determined by the degree of dilution. As a result, acids should always be handled with caution.
• Dilute acids can also cause blue litmus paper to become red.
• When opposed to concentrated acids, dilute acids contain a lower concentration of hydrogen ions.
• When compared to concentrated acids, dilute acids have a greater pH.
• They are relatively simple to work with.
• When they react with metals, they emit hydrogen gas as,

Acid + Metal  ⇢  Ionic compound + Hydrogen (⇡)

For example,

Zn + 2HCl  ⇢  ZnCl₂ + H₂ (⇡)

• They combine with an acid to create salt and water.

Acid + Base  ⇢  Salt + Water

For example,

HCl + NaOH  ⇢  NaCl + H₂O 

Formation of Dilute Acids: How Diluted acids are prepared?

The process of dilution takes place by adding concentrated acid in water with continuous stirring. The process is highly exothermic in nature because of which it cannot be performed in a reverse way. We don’t add water to the concentrated acid as a large amount of heat will evolve and explosions are possible. But when acid is added to water the amount of heat evolved is gradually absorbed by a large amount of water.

Therefore, by adding water to acid, water molecules assist to decrease the concentration of ions in the solution. The pH gradually rises towards 7. As a result, the acid loses its acidity.

While conducting the operation, diluting acids might be quite dangerous. As a result, safety precautions such as lab coats, gloves, and so on should be taken when conducting it. The acid should be introduced to the water after the concentrations of acid and water have been accurately measured. When water is introduced to acid, a large quantity of energy is released, which can produce caustic vapours and droplets to spray on you. Because this heat must be absorbed, it is preferable to add acid to water.

Handling and Storage of Diluted Acids

Acid dilution should be done with adequate safety measures. To avoid injury, we should use suitable PPE such as chemical-resistant aprons, chemical-resistant gloves, and chemical splash goggles when handling them. Breathing should be avoided since certain acids might be harmful if breathed. The dilution should ideally take place in a fume hood.

Small quantities of dilute acids should be stored after carefully marking them with the concentration and pH. Acid chloride and fuming acids should be kept in well-ventilated locations. Flammable liquids should be kept separate and labelled with a warning sign.

Uses of Diluted acid

• Diluted hydrochloric acid is used for cleaning surfaces, medical treatments, production of batteries, etc.
• Acetic acid is used as a daily food item and as a cleaning agent.
• Other acids like sulphuric acid, nitric acid, etc are used in their diluted form in laboratories for educational purposes.

Sample Questions

Question 1: Why are metallic containers made of brass has a coating of tin?

Answer:

Metals are reactive to acid and form corresponding ionic compounds. But tin is nonreactive to acids which prevent the poisoning of food.

Question 2: Why it is recommended to add acid in water during dilution of acid?

Answer:

It is recommended to add acid to water during the process because the process is highly exothermic in nature. While adding acid gradually in to the water the amount of heat produced is absorbed by the large amount of water.

Question 3: Why food items like curd and other dairy products should not be stored in copper vessels?

Answer:

The dairy products like curd contains lactic acid. When we store acidic food in brass or copper vessels they react with the given metal and form corresponding compounds which causes food poisoning.

Question 4: What will happen if water is added to concentrated acid?

Answer:

If water is added to any concentrated acid a large amount of heat will evolve which will change some of the water into vapor and acid will splash all over.

Question 5: What happens to the pH value of a diluted acid?

Answer:

The pH value of a substance depends on the concentration of hydrogen ions (H+) in it. The pH value of acid is directly proportional to its level of dilution. Hence, diluted acid has a higher pH value than concentrated acid.

Question 6: How to store diluted acid?

Answer:

Diluted acids should be stored in small quantities with proper labeling mentioning about its concentration level and pH value. Also, a warning should be written on the container if the liquid is flammable or a fuming acid. Fuming acids should be packed in ventilated areas. And flammable acids should also be kept separately in checked temperature.