Question

We add a 1.20-g sample of dry ice to a 755-mL flask containing nitrogen gas at a temperature of 25.0 C and a pressure of 725mmHg. The dry ice sublimes (converts from solid to gas) and the mixture returns to 25.0 C. What is the total pressure in the flask?

Answer 1

Answer:

Total pressure is 1396 mmHg

Explanation:

By:

PV/RT = n

It is possible to obtain the initial moles of nitrogen gas, where:

P is pressure (725 mmHg = 0,954 atm)

V is volume (0,755L)

R is gas constant (0,082atmL/molK)

T is temperature (25,0°C = 298,15 K)

Replacing:

n = 0,02946 moles of nitrogen gas.

The moles of dry ice (CO₂; molar mass= 44,01 g/mol) are:

1,20 g × (1mol/44,01g) = 0,02727 moles of dry ice.

When dry ice sublimes, total moles are:

0,02727 + 0,02946 = 0,05673 moles

With the temperature (25,0°C = 298,15 K) and volume (0,755L) it is possible to obtain total pressure, thus:

P = nRT/V

Replacing:

P = 1,837 atm × (760 mmHg/1atm) = 1396 mmHg

I hope it helps!