Question

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?

Answer 1

Answer:

Br

Explanation:

Given data:

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.