Answer:
The molar mass is 180.2 g/mol
Explanation:
<u>Step 1:</u> Data given
% of F = 70.4 %
Density = 4.5 g/L
Temperature = 20 °C
Pressure = 1 atm
<u>Step 2:</u> Calculate the number of moles
PV = nRT
⇒ with P = the pressure = 1.00 atm
⇒ with V = the volume = Assume this is 1L
⇒ with n = the number of moles = TO BE DETERMINED
⇒ R = the gas constant = 0.08206 L*atm/K*mol
⇒ T = the temperature : 20°C = 293 Kelvin
1 atm*1L= n(0.08206 L-atm/mol-K)*(293 K)
n = 0.04159 moles
<u>Step 3</u>: Calculate molar mass
Molar mass = Mass / moles
4.5 grams / 0.04159 moles = 108.2 g/mol
<u>Step 4:</u> Calculate moles of F
Moles = Mass / molar mass
Moles F = 70.4 g / 19 g/mol
Moles F = 3.70 moles
Moles S = 29.6g / 32.07 g/mol
Moles S = 0.923 moles S
<u>Step 5:</u> Divide by the smallest amount of moles
F = 3.70 / 0.923 = 4
S = 0.923 / 0.923 = 1
The empirical formula is SF4
The molar mass of SF4 = 32.07 + 4*19 = 108.07 g/mol
This means the empirical formula is the same as the molecular formula SF4
The molar mass is 180.2 g/mol
