Question

It is found that 250. mL of a gas at 0°C and a pressure of 1 atm (STP) has a mass of 0.677

g. What is the molar mass?

Answer 1

(1*.250)/(.08206*273)=.0111595
(.677)/(.0111595)=60.6656g/mol

Answer 2

MM = 60.4464 g/mol

Step-by-step explanation:

To do this, we need to use the ideal gas equation which is the following:

PV = nRT (1)

Where:

P: Pressure (atm)

V: Volume (L)

n: moles (mol)

R: gas constant (0.082 L atm / mol K)

T: Temperature (K)

We have the volume which is 250 mL (This is taken to Liter), and the pressure of 1 atm and 0°C so, we first calculate the moles. Solving from (1) the moles, we have:

n = PV/RT (2)

Before we solve for n, let's convert the units of volume and temperature:

V = 250 / 1000 = 0.25 L

T: 0 + 273 = 273 K

Now we can calculate the moles:

n = 1 * 0.25 / 0.082 * 273

n = 0.0112 moles

Now to calculate the molar mass, we use the following expression and solve for MM:

n = m/MM

MM = m/n (3)

So now, let's calculate the molar mass of the gas:

MM = 0.677 / 0.0112

MM = 60.4464 g/mol

This is the molar mass of the gas.