Question

A sample of liquid acetone is placed in a 25.0 mL flask and vaporized by the heating to 75° C at 1.02 ATM. The vapor weighs 5.87 g. What is the number of moles of the acetone?

Answer 1

To determine the number of moles of acetone, we can use the ideal gas law equation:

PV = nRT

Where: P = pressure (in atmospheres) V = volume (in liters) n = number of moles R = ideal gas constant (0.0821 L·atm/(mol·K)) T = temperature (in Kelvin)

First, we need to convert the given temperature from Celsius to Kelvin:

T = 75°C + 273.15 = 348.15 K

Next, we can rearrange the ideal gas law equation to solve for the number of moles:

n = PV / RT

Substituting the given values:

P = 1.02 atm V = 25.0 mL = 0.0250 L R = 0.0821 L·atm/(mol·K) T = 348.15 K

n = (1.02 atm * 0.0250 L) / (0.0821 L·atm/(mol·K) * 348.15 K)

Calculating this expression:

n = 0.0311 mol

Therefore, the number of moles of acetone in the vapor is approximately 0.0311 mol.