Question

chlorine pentafluoride gas is collected at 17.0°c in an evacuated flask with a measured volume of 5.0 l. when all the gas has been collected, the pressure in the flask is measured to be 0.410 atm. calculate the mass and number of moles of chlorine pentafluoride gas that were collected. be sure your answer has the correct number of significant digits. mass: g mole: mol

Explanation:

Step1: Convert temperature to Kelvin

$$T = 17.0 + 273.15=290.15\space K$$

Step2: Use ideal gas law \(PV = nRT\) to find moles (\(n\))

Ideal gas constant \(R = 0.0821\space L\cdot atm/(mol\cdot K)\), \(P = 0.410\space atm\), \(V = 5.0\space L\)
$$n=\frac{PV}{RT}=\frac{0.410\times5.0}{0.0821\times290.15}$$
$$n=\frac{2.05}{23.821315}\approx0.086\space mol$$

Step3: Calculate molar mass of \(ClF_5\)

Molar mass of \(Cl = 35.45\space g/mol\), molar mass of \(F= 19.00\space g/mol\)
Molar mass of \(ClF_5=35.45+(5\times19.00)=35.45 + 95=130.45\space g/mol\)

Step4: Calculate mass (\(m\))

$$m=n\times M$$
$$m = 0.086\times130.45\approx11\space g$$

Answer:

mass: \(11\space g\)
mole: \(0.086\space mol\)