A given solution of NaOH contains 2.00 g of NaOH per litre of solution. Calculate the molarity of this solution.

Answer

To calculate the molarity of the given NaOH solution, we will follow these steps:

### Step 1: Understand the definition of molarity
Molarity (M) is defined as the number of moles of solute per liter of solution. The formula for molarity is:
\[ M = \frac{\text{Number of moles of solute}}{\text{Volume of solution in liters}} \]

### Step 2: Calculate the number of moles of NaOH
To find the number of moles, we use the formula:
\[ \text{Number of moles} = \frac{\text{mass of solute (g)}}{\text{molar mass of solute (g/mol)}} \]

Given:
- Mass of NaOH = 2.00 g

Next, we need to calculate the molar mass of NaOH:
- Sodium (Na) = 23 g/mol
- Oxygen (O) = 16 g/mol
- Hydrogen (H) = 1 g/mol

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

Now, we can calculate the number of moles of NaOH:
\[ \text{Number of moles of NaOH} = \frac{2.00 \text{ g}}{40 \text{ g/mol}} = 0.05 \text{ moles} \]

### Step 3: Calculate the molarity of the solution
Now that we have the number of moles, we can calculate the molarity:
\[ M = \frac{\text{Number of moles of NaOH}}{\text{Volume of solution in liters}} \]

Given that the volume of the solution is 1 liter:
\[ M = \frac{0.05 \text{ moles}}{1 \text{ L}} = 0.05 \text{ M} \]

### Final Answer
The molarity of the NaOH solution is:
\[ \text{Molarity} = 0.05 \text{ moles per liter} \]

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