4.0 g of NaOH contains

Options

A. `6.022 xx 10^(23)` atoms of H
B. 4 g atoms of Na
C. `6.022 xx 10^(22)` atoms of Na
D. 4 moles of NaOH

Answer

To solve the problem of how many atoms are contained in 4.0 g of NaOH, we will follow these steps:

### Step 1: Calculate the molar mass of NaOH
The molar mass of NaOH can be calculated by adding the atomic masses of sodium (Na), oxygen (O), and hydrogen (H):
- Atomic mass of Na = 23 g/mol
- Atomic mass of H = 1 g/mol
- Atomic mass of O = 16 g/mol

\[ \text{Molar mass of NaOH} = 23 + 1 + 16 = 40 \text{ g/mol} \]

### Step 2: Calculate the number of moles in 4.0 g of NaOH
Using the molar mass, we can find the number of moles in 4.0 g of NaOH:

\[ \text{Number of moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{4.0 \text{ g}}{40 \text{ g/mol}} = 0.1 \text{ moles} \]

### Step 3: Calculate the number of formula units (or molecules) in 0.1 moles of NaOH
Using Avogadro's number, which is \(6.022 \times 10^{23}\) entities/mol, we can find the total number of NaOH formula units in 0.1 moles:

\[ \text{Number of NaOH units} = 0.1 \text{ moles} \times 6.022 \times 10^{23} \text{ units/mole} = 6.022 \times 10^{22} \text{ units} \]

### Step 4: Determine the number of atoms in NaOH
Each formula unit of NaOH contains one sodium (Na) atom, one oxygen (O) atom, and one hydrogen (H) atom. Therefore, the total number of atoms in 6.022 x 10^22 units of NaOH is:

\[ \text{Total atoms} = 6.022 \times 10^{22} \text{ NaOH units} \times 3 \text{ atoms/unit} = 1.8066 \times 10^{23} \text{ atoms} \]

However, since the question specifically asks for the number of atoms of sodium and hydrogen, we can conclude:

- Number of sodium atoms = \(6.022 \times 10^{22}\)
- Number of hydrogen atoms = \(6.022 \times 10^{22}\)

### Conclusion
The correct answer from the options given is that 4.0 g of NaOH contains \(6.022 \times 10^{22}\) atoms of sodium.