39 Insightful Publications
In this experiment, we have learned how to prepare carbon dioxide in a lab.
Carbon dioxide gas, represented by the chemical formula CO2, can be prepared in the laboratory by the action of dilute acids on calcium carbonate. Calcium carbonate occurs naturally in the form of marble, chalk and limestones.
- CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)
Similarly, chemical reaction HCl and Na2CO3 yields salt, H2O and CO2. Let us explore.
HCl is a strong acid that completely dissociates in water to form H+ and Cl– ions. Na2CO3 is a basic salt because it is formed by the reaction of a strong base like NaOH and a weak acid like carbonic acid (H2CO3).
When dil. HCl reacts with any metal carbonate like sodium carbonate or sodium bicarbonate, and a brisk effervescence of CO2 gas appears.
- 2HCl (aq) + Na2CO3 (s) → 2NaCl (aq) + H2O (l) + CO2 (g)
From this experiment, we conclude that the reaction of hydrochloric acid with sodium carbonate produces a brisk effervescence of gas, which is carbon dioxide, and when it is passed through lime water, it turns milky due to the formation of insoluble calcium carbonate.
A similar reaction also occurs when hydrochloric acid reacts with sodium bicarbonate.
FAQs on Factors Affecting Corrosion
Q1. What is Rusting of Iron?
Answer: Iron, when exposed to moist air (air and water) for a long time, acquires a coating of a brown, flaky substance called rust. This phenomenon is known as rusting.
Q2. What type of reaction is Rusting of Iron: Oxidation or reduction?
Answer: Reddish brown powder, also known as rust, is formed due to oxidation of iron in the presence of moisture and oxygen.
Q3. Briefly describe the corrosion of copper.
Answer: When Copper metal is exposed to air, it reacts with moisture and gases present in the atmosphere and forms a coloured coating on its surface, and the reaction is as follows:
2Cu + H2O + O2 + CO2→ Cu(OH)2 + CuCO3
Therefore, from the above reaction, we can see that a mixture of copper carbonate and copper hydroxide (Cu(OH)2+CuCO3) is formed which is green in color.
Q4. Which gas in the atmosphere is responsible for the tarnish of silver metal?
Answer: The silver oxide (Ag2O) formed reacts with Hydrogen Sulphide (H2S) present in the atmosphere to produce Silver Sulphide (Ag2S) as a product:
Ag2O+H2S→Ag2S+H2O
Q5. What colour coating is obtained due to the tarnish of silver?
Answer: Due to silver’s corrosion, the silver sulphide is black in colour.
JEE Main