The quick lime as it comes from kiln is called ...............
Try it first: pick an option, then read the explanation.
Understanding the Forms of Lime
After limestone is heated in a kiln (calcination), the resulting product is quicklime (CaO). However, this quicklime exists in different physical forms and states, each with a specific name. It's important to distinguish between the chemical classification (like fat or hydraulic lime) and the name for its physical state (like lump or hydrated lime).
Detailed Analysis of the Options
C. Lump lime
This is the correct answer. When quicklime comes out of the kiln, it is in the form of irregular, solid chunks. This physical form is known as lump lime. It is the raw, unslaked quicklime before it undergoes any further processing like crushing or slaking.
A. Milk lime
This is incorrect. Milk of lime (or lime wash) is a suspension of slaked/hydrated lime in a large amount of water, forming a milky liquid used for whitewashing.
B. Hydraulic lime
This is incorrect. Hydraulic lime is a chemical classification for lime that contains clay and can set under water. While it also comes from a kiln as lumps, "hydraulic lime" describes its chemical property, not its initial physical form.
D. Hydrated lime
This is incorrect. Hydrated lime (or slaked lime) is the fine powder that is produced *after* lump lime has been treated with water in the process of slaking.
Summary: Physical States of Lime
| Term | Description | State |
|---|---|---|
| Lump Lime | Quicklime as it comes from the kiln. | Solid, irregular chunks. |
| Hydrated Lime | Quicklime after reacting with water. | Fine powder. |
| Lime Putty | Hydrated lime mixed with excess water. | Thick paste. |
| Milk of Lime | Hydrated lime suspended in a large volume of water. | Thin, milky liquid. |
Study Tips
- Lump = Shape: The key is in the name. "Lump lime" describes the physical shape of the material as it comes from the kiln.
- Follow the Process: Remember the sequence: Lump Lime (from kiln) -> add water (slaking) -> Hydrated Lime (powder) -> add more water -> Lime Putty (paste) -> add even more water -> Milk of Lime (liquid).
- Form vs. Type: Don't confuse physical form (lump) with chemical type (hydraulic). Any type of quicklime (fat or hydraulic) will be in the form of lump lime when it first exits the kiln.