Number of hydrogen atoms in a repeating unit of a polymer used to make unbreakable crockery is _______. (Integer answer)

Answer

To determine the number of hydrogen atoms in a repeating unit of the polymer used to make unbreakable crockery, we need to analyze the structure of the polymer, which is formed from melamine and formaldehyde.

### Step-by-Step Solution:

1. **Identify the Components**: The polymer used for unbreakable crockery is melamine-formaldehyde resin. The two main components are melamine and formaldehyde.

2. **Write the Structure of Melamine**: Melamine has the following structure:
```
NH2
|
NH-C-NH2
|
NH2
```
In this structure, there are 6 hydrogen atoms attached to the nitrogen atoms.

3. **Write the Structure of Formaldehyde**: The structure of formaldehyde (CH2O) can be represented as:
```
H
|
H-C=O
```
Here, formaldehyde contributes 2 hydrogen atoms.

4. **Combine the Structures**: When melamine reacts with formaldehyde, they form a repeating unit. The repeating unit can be represented as:
```
NH
|
CH2
|
NH
|
NH2
```
This structure indicates that the repeating unit consists of:
- 1 nitrogen with 1 hydrogen (NH)
- 1 carbon with 2 hydrogens (CH2)
- 1 nitrogen with 1 hydrogen (NH)
- 1 nitrogen with 2 hydrogens (NH2)

5. **Count the Hydrogen Atoms**: Now, we can count the hydrogen atoms in the repeating unit:
- From the first NH: 1 hydrogen
- From CH2: 2 hydrogens
- From the second NH: 1 hydrogen
- From the NH2: 2 hydrogens

Total hydrogen atoms = 1 + 2 + 1 + 2 = 6 hydrogen atoms.

6. **Final Answer**: Therefore, the number of hydrogen atoms in a repeating unit of the polymer used to make unbreakable crockery is **6**.