The molarity of 900 g of water is

Options

A. 50 M
B. 55.5 M
C. 5 M
D. cannot be calculated

Explanation

To calculate the molarity of 900 grams of water, we will follow these steps:

### Step 1: Calculate the number of moles of water.
To find the number of moles, we use the formula:

\[ \text{Number of moles} = \frac{\text{Given weight (g)}}{\text{Molecular weight (g/mol)}} \]

The molecular weight of water (H₂O) is approximately 18 g/mol.

Given weight of water = 900 g

\[ \text{Number of moles} = \frac{900 \, \text{g}}{18 \, \text{g/mol}} = 50 \, \text{moles} \]

### Step 2: Convert the mass of water to volume.
Since the density of water is approximately 1 g/mL, the volume of 900 g of water can be calculated as follows:

\[ \text{Volume (mL)} = \text{Mass (g)} \div \text{Density (g/mL)} \]

Given that the density of water is 1 g/mL:

\[ \text{Volume} = \frac{900 \, \text{g}}{1 \, \text{g/mL}} = 900 \, \text{mL} \]

### Step 3: Convert the volume from mL to L.
To convert mL to L, we divide by 1000:

\[ \text{Volume (L)} = \frac{900 \, \text{mL}}{1000} = 0.9 \, \text{L} \]

### Step 4: Calculate the molarity.
Molarity (M) is defined as the number of moles of solute per liter of solution:

\[ \text{Molarity (M)} = \frac{\text{Number of moles}}{\text{Volume (L)}} \]

Substituting the values we calculated:

\[ \text{Molarity} = \frac{50 \, \text{moles}}{0.9 \, \text{L}} \approx 55.56 \, \text{M} \]

### Final Answer:
The molarity of 900 g of water is approximately **55.56 M**.

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