To determine the number of moles of magnesium chloride (MgCl2) present in a 55.0 gram sample, follow these steps:
1. Identify the molar mass of MgCl2: The molar mass is the mass of one mole of a substance. For magnesium chloride, this is the sum of the molar masses of magnesium (Mg) and two chlorine (Cl) atoms.
- Molar mass of Mg: 24.305 g/mol
- Molar mass of Cl: 35.453 g/mol
- Molar mass of MgCl2 = 24.305 g/mol (Mg) + 2 × 35.453 g/mol (Cl) = 95.211 g/mol
2. Measure the mass of the MgCl2 sample: Here, the mass is given as 55.0 grams.
3. Use the formula to calculate the number of moles:
[tex]\[
\text{Number of moles} = \frac{\text{mass}}{\text{molar mass}}
\][/tex]
4. Substitute the values into the formula:
[tex]\[
\text{Number of moles} = \frac{55.0 \text{ grams}}{95.211 \text{ g/mol}}
\][/tex]
5. Perform the division:
[tex]\[
\text{Number of moles} \approx 0.5777
\][/tex]
Therefore, approximately 0.5777 moles of magnesium chloride are present in a 55.0 gram sample.
