State the oxidation number of carbonyl carbon in methanal and methanoic acid respectively :

Explanation

To determine the oxidation number of the carbonyl carbon in methanal (HCHO) and methanoic acid (HCOOH), we will analyze each compound step by step.

### Step 1: Identify the structure of methanal (HCHO)
Methanal, commonly known as formaldehyde, has the following structure:
```
H
|
H—C=O
```
In this structure, the carbonyl carbon is the carbon atom that is double-bonded to the oxygen atom.

### Step 2: Assign oxidation numbers for methanal
The oxidation number (x) of carbon in methanal can be calculated using the formula:
\[ \text{Total oxidation number} = 0 \]
Since methanal is a neutral molecule, the sum of the oxidation states must equal zero.

- Hydrogen (H) has an oxidation state of +1 (two H atoms contribute +2).
- Oxygen (O) has an oxidation state of -2.

Setting up the equation:
\[ +1 + x - 2 = 0 \]
\[ x - 1 = 0 \]
\[ x = +1 \]

### Step 3: Conclusion for methanal
The oxidation number of the carbonyl carbon in methanal is **+1**.

### Step 4: Identify the structure of methanoic acid (HCOOH)
Methanoic acid, also known as formic acid, has the following structure:
```
O
||
H—C—OH
|
H
```
Again, the carbonyl carbon is the carbon atom that is double-bonded to the oxygen atom.

### Step 5: Assign oxidation numbers for methanoic acid
The oxidation number (y) of carbon in methanoic acid can be calculated similarly:
\[ \text{Total oxidation number} = 0 \]
Since methanoic acid is also a neutral molecule, the sum of the oxidation states must equal zero.

- Hydrogen (H) has an oxidation state of +1 (two H atoms contribute +2).
- Each oxygen (O) has an oxidation state of -2 (two O atoms contribute -4).

Setting up the equation:
\[ +1 + y - 2 - 2 = 0 \]
\[ y - 3 = 0 \]
\[ y = +2 \]

### Step 6: Conclusion for methanoic acid
The oxidation number of the carbonyl carbon in methanoic acid is **+2**.

### Final Answer
- The oxidation number of carbonyl carbon in methanal is **+1**.
- The oxidation number of carbonyl carbon in methanoic acid is **+2**.