Black ash is: A. CaS + NaHCO3 B. CaSO4 + Na2CO3 C. CaSO4 + NaHCO3 D. CaS + Na2CO3
The Correct Answer and Explanation is:
The correct answer is D. CaS + Na2CO3.
Explanation: Black ash is produced from the combustion of certain materials, particularly plant matter, and typically contains various compounds such as calcium salts, sodium carbonate, and others. It is primarily a mixture of Calcium Sulfide (CaS) and Sodium Carbonate (Na2CO3).
When certain materials, like plant biomass, are burned at high temperatures, the resulting ash is mainly composed of alkaline compounds such as sodium and calcium salts. Specifically:
- Calcium Sulfide (CaS): This compound forms when sulfur present in the material reacts with calcium at high temperatures during combustion. The sulfur dioxide (SO2) formed from burning the sulfur combines with calcium oxide (CaO) to form calcium sulfide (CaS).
- Sodium Carbonate (Na2CO3): Sodium comes from other elements in the material being burned, such as potassium or sodium salts, and reacts with the carbon dioxide (CO2) produced during combustion to form sodium carbonate.
When these two compounds, CaS and Na2CO3, combine, they contribute to the characteristic composition of black ash.
The other options involve different combinations of calcium sulfate (CaSO4) and sodium bicarbonate (NaHCO3), but these are not typical of what is found in black ash. Calcium sulfate and sodium bicarbonate are more likely to form under different combustion conditions or with different materials.
In summary, the mixture of CaS and Na2CO3 is a defining feature of black ash produced by high-temperature combustion of materials, making Option D the correct answer.
