Chemistry College

A 0.465 g sample of an unknown compound occupies 245 ml at 298 k and 1.22 atm. what is the molar mass of the unknown compound?
a.26.3 g/mol
b.33.9 g/mol
c.12.2 g/mol
d.38.0 g/mol
e.81.8 g/mol

Answers

Answer 1
we can find the number of moles of gas using the ideal gas law equation
                                                                                                 
PV = nRT
                                                                                                 
where P - pressure - 1.22 atm
                                               
V - volume - 0.245 L
                                                                                               
n - number of moles
                                                                                               
R - gas constant - 0.08206 L.atm/mol.K
                                               
T - temperature - 298 K
                                                                                               
substituting the values in the equation
                                                   
1.22 atm x 0.245 L = n x 0.08206 L.atm/mol.K x 298 K
                                               
n = 0.0122 mol
                                                                                               
molar mass of compound = mass present / number of moles therefore molar mass = 0.465 g / 0.0122 mol = 38.1 g/mol
the answer is d) 38.0 g/mol
Answer 2

Answer: Option (d) is the correct answer.

Explanation:

It is know that for an ideal gas PV = nRT

where     P = pressure

               V = volume

               n = number of moles = [tex]\frac{mass}{molar mass}[/tex]

                R = gas constant = 0.082 [tex]L atm K^{-1} mol^{-1}[/tex]

                T = temperature

Therefore, put the given values in the formula above as follows.

                   PV = nRT

or,               PV = [tex]\frac{mass}{molar mass}RT[/tex]

               [tex]1.22 atm \times 0.245 L = \frac{0.465 g}{molar mass} \times 0.082 L atm K^{-1} mol^{-1} \times 298 K[/tex]

                molar mass = 38.12 g/mol

                                    = 38.0 g/mol (approx)

Therefore, we can conclude that the molar mass of the unknown compound is 38.0 g/mol.

Related Questions

To study Earth’s interior, geologists often rely on indirect methods, such as evidence from fossils. true or false

Answers

Answer:

the answer is false, the person that said true is incorect.

Explanation:

Answer: FALSE

Explanation:To study Earth’s interior, geologists often rely on indirect methods, such as evidence from fossils.

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