A 2.80 -g sample of an unknown chlorofluorocarbon is decomposed and produces 557mL of chlorine gas at a pressure of 750mm Hg and a temperature of 298K .
What is the percent chlorine (by mass) in the unknown chlorofluorocarbon?
Use the ideal gas law to find the moles of chlorine gas Cl2 :
n=PV/RT
then, change the moles to mass using the mole mass of Cl2
finally, percentCl is mass/2.80g
To determine the percent chlorine (by mass) in the unknown chlorofluorocarbon, we can use the ideal gas law and the molar mass of chlorine.
First, let's calculate the number of moles of chlorine gas produced. We can use the ideal gas law equation, PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.
Given:
Pressure (P) = 750 mm Hg
Volume (V) = 557 mL
Temperature (T) = 298 K
Convert the pressure from mm Hg to atm:
1 atm = 760 mm Hg
So, 750 mm Hg = 750/760 atm
Convert the volume from mL to L:
1 L = 1000 mL
So, 557 mL = 557/1000 L
Using the ideal gas law equation, we can solve for n:
n = (PV) / (RT)
Substituting the given values into the equation, we get:
n = ((750/760) atm) * (557/1000 L) / (0.0821 L*atm/mol*K) * 298 K
Calculate the result to find the number of moles of chlorine gas produced.
Next, we need to relate the moles of chlorine gas produced to the molar mass of chlorine to find the mass of chlorine.
The molar mass of chlorine is approximately 35.45 g/mol.
Finally, to calculate the percent chlorine (by mass) in the unknown chlorofluorocarbon, divide the mass of chlorine by the initial mass of the chlorofluorocarbon sample (2.80 g) and multiply by 100.
I hope this helps! If you have any more questions, feel free to ask.