A 2.85 g sample of an unknown chlorofluorocarbon is decomposed and produces 558 mL of chlorine gas at a pressure of 756 mmHg and a temperature of 298 K.What is the percent chlorine (by mass) in the unknown chlorofluorocarbon?
Use PV = nRT and solve for n = number of moles Cl2.
Convert moles Cl2 to g Cl2.
%Cl = (mass chlorine/2.85)*100 = ??
To determine the percent chlorine (by mass) in the unknown chlorofluorocarbon, we need to calculate the number of moles of chlorine gas produced and then compare it to the total mass of the chlorofluorocarbon.
Here's how you can approach the problem:
1. Convert the given pressure from mmHg to atm by dividing it by 760 mmHg/atm. In this case, 756 mmHg ÷ 760 mmHg/atm = 0.9947 atm.
2. Use the ideal gas law equation, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature. Rearrange the equation to solve for n:
n = PV / RT
Substitute the given values into the equation:
n = (0.9947 atm) * (0.558 L) / [(0.0821 L·atm/mol·K) * (298 K)]
Calculate the value of n. This will give you the number of moles of chlorine gas produced.
3. Determine the molar mass of chlorine (Cl₂). Each chlorine molecule has a molar mass of 35.45 g/mol.
4. Calculate the mass of chlorine using the equation:
mass = moles * molar mass
Substitute the values into the equation:
mass = (number of moles of chlorine gas) * (molar mass of chlorine)
Calculate the mass of chlorine.
5. Calculate the percent by mass of chlorine in the chlorofluorocarbon using the equation:
percent by mass = (mass of chlorine / total mass of chlorofluorocarbon) * 100
Substitute the values into the equation and calculate the percent.
By following these steps, you can determine the percent chlorine (by mass) in the unknown chlorofluorocarbon.