Question

A 5.07 g sample of water is introduced into a 0.668 L flask containing some C₂H₂ gas. The flask is heated to 233.53 °C at which temperature all of the water is converted to the gaseous phase, giving a total pressure in the flask of 20.932 atm.

1. Calculate P_H2O (in atm) in the flask at 233.53 °C.
Report your answer to **((three decimal places)) in standard notation (i.e. 1.234 atm).

2-Calculate P_C2H2 (in atm) in the flask at 233.53 °C.
Report your answer to**((( three decimal places)) in standard notation (i.e. 1.234 atm)

3. Calculate the mass of C₂H₂ (in grams) in the flask at 233.53 °C.
Report your answer to ***(((three significant figures.)))

4. Calculate X_H2O in the flask at 233.53 °C.
Report your answer to ***(((three significant figures)))

Answer 1

Solution :-

1. Calculate P_H2O (in atm) in the flask at 233.53 °C.
Report your answer to **((three decimal places)) in standard notation (i.e. 1.234 atm).

Solution :-

Lets first calculate the moles of water

Moles of water = 5.07 g /18.0148 g per mol = 0.28144 mol

Now we can calculate the pressure of the H2O using the ideal gas law formula

V= 0.668 L

T= 233.53 +273.15 = 506.68 K

PV=nRT

P =nRT/V

= 0.28144 mol * 0.08206 L atm per mol K * 506.68 K / 0.668 L

= 17.518 atm

So the partial pressure of the H2O = 17.518 atm

2-Calculate P_C2H2 (in atm) in the flask at 233.53 °C.
Report your answer to**((( three decimal places)) in standard notation (i.e. 1.234 atm)

Solution :-

P C2H2 = total pressure - P H2O

             = 20.932 atm – 17.518 atm

            = 3.414 atm

3. Calculate the mass of C₂H₂ (in grams) in the flask at 233.53 °C.
Report your answer to ***(((three significant figures.)))

Solution :-

Lets calculate the moles of the C2H2 using the ideal gas formula

n= PV/RT

= 3.414 atm* 0.668 L / 0.08206 L atm per mol K * 506.68 K

= 0.05485 mol C2H2

Now lets calculate the mass of C2H2

Mass of C2H2 = moles * molar mass

                         = 0.05485 mol * 26.04 g per mol

                         = 1.43 g C2H2

4. Calculate X_H2O in the flask at 233.53 °C.
Report your answer to ***(((three significant figures)))

Solution :-

Mole fraction can ce calculated using the partial pressure and total pressure as follows

XH2O = P H2O / total pressure

           = 17.518 atm / 20.932 atm

            = 0.837