1 g Mg was burnt in a closed vessel containing 2 g oxygen. Which of the following are not correct?

Options

A. 0.25 g of Mg will be left unburnt
B. 1.33 of `O_(2)` will be left unreacted
C. 2.5 g of MgO will be formed
D. The mixture at the end will weigh 3 g.

Explanation

To solve the question regarding the combustion of magnesium in a closed vessel containing oxygen, we will analyze the reaction step by step.

### Step 1: Identify the Reaction
When magnesium (Mg) burns in the presence of oxygen (O₂), it forms magnesium oxide (MgO). The balanced chemical equation for this reaction is:
\[ 2 \text{Mg} + \text{O}_2 \rightarrow 2 \text{MgO} \]

### Step 2: Calculate Moles of Reactants
- **Molar mass of magnesium (Mg)**: 24 g/mol
- **Molar mass of oxygen (O₂)**: 32 g/mol

Now, calculate the moles of each reactant:
- Moles of Mg in 1 g:
\[ \text{Moles of Mg} = \frac{1 \text{ g}}{24 \text{ g/mol}} = 0.04167 \text{ mol} \]
- Moles of O₂ in 2 g:
\[ \text{Moles of O}_2 = \frac{2 \text{ g}}{32 \text{ g/mol}} = 0.0625 \text{ mol} \]

### Step 3: Determine the Limiting Reagent
From the balanced equation, 2 moles of Mg react with 1 mole of O₂. Therefore, for 0.04167 moles of Mg, the required moles of O₂ are:
\[ \text{Required O}_2 = \frac{0.04167 \text{ mol Mg}}{2} = 0.02083 \text{ mol O}_2 \]

Since we have 0.0625 moles of O₂ available, O₂ is in excess, and Mg is the limiting reagent.

### Step 4: Calculate the Amount of MgO Formed
According to the reaction, 2 moles of Mg produce 2 moles of MgO. Therefore, 0.04167 moles of Mg will produce an equal amount of moles of MgO:
\[ \text{Moles of MgO} = 0.04167 \text{ mol} \]

Now, convert moles of MgO to grams:
\[ \text{Molar mass of MgO} = 24 \text{ g/mol (Mg)} + 16 \text{ g/mol (O)} = 40 \text{ g/mol} \]
\[ \text{Mass of MgO} = 0.04167 \text{ mol} \times 40 \text{ g/mol} = 1.667 \text{ g} \]

### Step 5: Calculate the Remaining Reactants
- **Oxygen consumed**:
\[ \text{O}_2 \text{ consumed} = 0.02083 \text{ mol} \times 32 \text{ g/mol} = 0.6667 \text{ g} \]

- **Oxygen left unreacted**:
\[ \text{O}_2 \text{ left} = 2 \text{ g} - 0.6667 \text{ g} = 1.3333 \text{ g} \]

### Step 6: Total Mass After Reaction
The total mass after the reaction will be the mass of unreacted oxygen plus the mass of magnesium oxide formed:
\[ \text{Total mass} = \text{Mass of MgO} + \text{Mass of unreacted O}_2 = 1.667 \text{ g} + 1.333 \text{ g} = 3 \text{ g} \]

### Conclusion
Now, let's summarize the findings:
1. **Mass of MgO formed**: 1.667 g (not 2.5 g)
2. **Mass of unreacted O₂**: 1.333 g
3. **Total mass of the mixture after the reaction**: 3 g

### Incorrect Statements
Based on the calculations:
- The statement that 2.5 g of MgO will be formed is incorrect.
- The statement regarding the amount of unreacted oxygen is correct.
- The statement about the total mass being 3 g is also correct.