A 0.239 gram sample of a gas in a 100-mL flask exerts a pressure of 603 mm Hg at 14 degrees Celsius. What is the gas?

Br

Explanation:

Given dа ta:

Mass of gas = 0.239 g

Volume of gas = 100 mL

Pressure exerted by gas = 603 mmHg

Temperature of gas = 14 °C

What is gas = ?

Solution:

Volume of gas = 100 mL (100mL * 1 L/1000 mL = 0.1 L)

Pressure exerted by gas = 603 mmHg (603/760 = 0.79 atm)

Temperature of gas = 14°C (14+273 = 287 K)

The given problem will be solve by using general gas equation,

PV = nRT

P = Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm. L / mol. K

T = temperature in kelvin

now we will calculate the number of moles.

n = PV/RT

n = 0.79 atm * 0.1 L / 0.0821 atm. L / mol. K * 287 K

n = 0.079 / 23.563 / mol

n = 0.003 mol

Molar mass of gas:

Number of moles = mass/molar mass

0.003 mol = 0.239 g / molar mass

Molar mass = 0.239 g / 0.003 mol

Molar mass = 79.7 g/mol

The molar mas of Br is 79.9 g/mol so it is closer to 79.7 thus given gas is Br.