# What is the mass of 3.81 mol of PH3?

#### Understand the Problem

The question is asking for the calculation of the mass of phosphine (PH3) given its amount in moles (3.81 mol). To find the mass, we will use the formula: mass = moles × molar mass. We need to calculate the molar mass of PH3 and then multiply it by 3.81 mol.

The mass of phosphine (PH₃) is approximately 129.6 g.

The mass of phosphine (PH₃) is approximately 129.6 g.

#### Steps to Solve

1. Calculate the molar mass of phosphine (PH₃)

To find the molar mass, we will add the atomic masses of all the atoms in the phosphine molecule:

• Phosphorus (P) has an atomic mass of about 31.00 g/mol
• Hydrogen (H) has an atomic mass of about 1.01 g/mol

Since there are one phosphorous atom and three hydrogen atoms in PH₃, we calculate as follows:

$$\text{Molar mass of PH}_3 = 31.00 , \text{g/mol} + (3 \times 1.01 , \text{g/mol})$$

2. Perform the multiplication

After calculating the molar mass, we multiply it by the number of moles to find the mass:

Let’s calculate the molar mass from step 1:

$$\text{Molar mass of PH}_3 = 31.00 , \text{g/mol} + 3.03 , \text{g/mol} = 34.03 , \text{g/mol}$$

Now, we calculate the mass:

$$\text{Mass} = \text{Moles} \times \text{Molar mass} = 3.81 , \text{mol} \times 34.03 , \text{g/mol}$$

3. Finish the calculations

Now, we can compute the final mass:

$$\text{Mass} = 3.81 , \text{mol} \times 34.03 , \text{g/mol} \approx 129.6 , \text{g}$$

The mass of phosphine (PH₃) is approximately 129.6 g.