Question

Thermal decomposition of lithium nitrate gives:

• A. LiO$_2$, O$_2$, NO$_2$
• B. Li$_2$O, O$_2$, N$_2$O
• C. Li$_2$O, O$_2$, N$_2$
• D. Li$_2$O, O$_2$, NO$_2$

Hint:

Thermal decomposition of lithium nitrate produces \( NO_2 \), unlike heavier alkali metal nitrates which form nitrites.

Answer 1

The Correct Option is D

Step 1: Thermal Decomposition of Lithium Nitrate
The decomposition reaction for lithium nitrate is: \[ 4LiNO_3 \rightarrow 2Li_2O + 4NO_2 + O_2 \] Step 2: Explanation of Products
Lithium nitrate decomposes to form lithium oxide (\( Li_2O \)), nitrogen dioxide (\( NO_2 \)), and oxygen (\( O_2 \)).
The presence of \( NO_2 \) and \( O_2 \) confirms the decomposition follows a distinct pathway compared to other nitrates.
Thus, the correct answer is (D).

Answer 2

Step 1: Identify the compound
The given compound is lithium nitrate, LiNO₃.
It is an alkali metal nitrate (Group 1 element).

Step 2: Understand thermal decomposition of nitrates
The behavior of metal nitrates upon heating depends on the group of the metal:
- Nitrates of alkali metals (except lithium) decompose to form nitrites and oxygen:
e.g., 2NaNO₃ → 2NaNO₂ + O₂
- Nitrates of lithium and all other metals decompose to give the metal oxide, nitrogen dioxide (NO₂), and oxygen (O₂):
e.g., 4LiNO₃ → 2Li₂O + 4NO₂ + O₂

Step 3: Apply the rule to lithium nitrate
Since lithium behaves differently from other Group 1 metals, its nitrate decomposes completely:
4LiNO₃ → 2Li₂O + 4NO₂ + O₂

Step 4: Write the products
On thermal decomposition, lithium nitrate gives:
- Lithium oxide (Li₂O)
- Nitrogen dioxide (NO₂)
- Oxygen gas (O₂)

Final Answer: Li₂O, NO₂, O₂