How many moles of benzene (C6H6) are there in a 7.8-g sample of benzene?
a. 0.100 mol
b. 1.00 mol
c. 7.81 mol
d. 610 mol
The correct answer and explanation is :
To determine the number of moles of benzene ((C_6H_6)) in a 7.8-g sample, we use the formula:
[
\text{Moles} = \frac{\text{Mass}}{\text{Molar Mass}}
]
Step 1: Find the molar mass of benzene ((C_6H_6))
The atomic masses of carbon (C) and hydrogen (H) are:
- Carbon (C): 12.01 g/mol
- Hydrogen (H): 1.008 g/mol
Now, calculate the molar mass of benzene:
[
(6 \times 12.01) + (6 \times 1.008) = 72.06 + 6.048 = 78.108 \text{ g/mol}
]
Step 2: Calculate the number of moles
[
\text{Moles of benzene} = \frac{7.8 \text{ g}}{78.108 \text{ g/mol}}
]
[
= 0.0999 \approx 0.100 \text{ mol}
]
Answer:
The correct answer is (a) 0.100 mol.
Explanation:
The mole concept is essential in chemistry as it allows us to relate mass to the number of molecules. The molar mass of benzene, 78.108 g/mol, represents the mass of one mole of benzene molecules. By dividing the given mass (7.8 g) by this molar mass, we determine the amount of benzene in moles. The answer is approximately 0.100 mol, meaning the sample contains about 0.1 moles of benzene molecules.
This calculation is useful in chemistry for determining reactant quantities, balancing chemical equations, and performing stoichiometric calculations. Understanding how to convert between grams and moles is crucial for laboratory work, chemical reactions, and industrial applications.
Now, I will generate an image representing this concept.
Here is the scientific illustration showing the calculation of moles of benzene (C₆H₆). It includes the step-by-step breakdown, molar mass calculation, formula, and final result.