what is the mass of 3.81 mol of ph3? show work on scratch paper! group of answer choices 34.0 g 3.81 g 8.92 g 130. g 0.112
The Correct Answer and Explanation is :
The Correct Answer is : 130.0 g
To find the mass of 3.81 moles of phosphine (( \text{PH}_3 )), we need to use the formula for calculating mass from moles, which is given by:
[
\text{Mass} = \text{Moles} \times \text{Molar Mass}
]
Step 1: Calculate the Molar Mass of ( \text{PH}_3 )
The molar mass of a compound is calculated by summing the atomic masses of all the atoms present in the molecule.
- Phosphorus (P) has an atomic mass of approximately 30.97 g/mol.
- Hydrogen (H) has an atomic mass of approximately 1.01 g/mol.
In ( \text{PH}_3 ), there is 1 phosphorus atom and 3 hydrogen atoms. Thus, the molar mass can be calculated as follows:
[
\text{Molar Mass of } \text{PH}_3 = (1 \times 30.97 \, \text{g/mol}) + (3 \times 1.01 \, \text{g/mol})
]
Calculating the contributions from each element:
[
\text{Molar Mass of } \text{PH}_3 = 30.97 \, \text{g/mol} + 3.03 \, \text{g/mol} = 34.00 \, \text{g/mol}
]
Step 2: Calculate the Mass of 3.81 moles of ( \text{PH}_3 )
Now that we have the molar mass, we can substitute the values into the mass formula:
[
\text{Mass} = 3.81 \, \text{mol} \times 34.00 \, \text{g/mol}
]
Calculating the mass:
[
\text{Mass} = 3.81 \times 34.00 = 129.54 \, \text{g}
]
Conclusion
The mass of 3.81 moles of ( \text{PH}_3 ) is approximately 130.0 g when rounded to three significant figures.
This process shows how to convert between moles and mass using the molar mass as a conversion factor. Understanding this relationship is essential in chemistry, especially when dealing with reactions and stoichiometry, as it allows for the calculation of the quantities of reactants and products in a chemical reaction.