Question

An unknown gas with a formula of HX is contained in a 25.0 L tank at 1.2 atm and 25.0 oC. What is the chemical formula of the gas if the mass of the gas is 44.7 g?

Answer 1

Answer:

HCl

Explanation:

Volume = 25L

Temperature = 25.0 oC + 273 = 298 K (Converting to kelvin units)

Pressure = 1.2 atm

Mass of gas = 44.7g

Formular of gas = HX

To solve this, we have to know the identity of X. One qay to do that is by obtaining the molecular mass of the compound.

To get the molar mass, we need the number of mole.

Using the ideal gas equation;

PV = nRT

where R = gas constant = 0.082 057 L atm K−1  mol−1

n = PV / RT

n = 1.2 * 25  / 0.082 057 * 298

n = 30  /  24.45

n = 1.227 mol

The relationship between number of moles and molar mass is given as;

Nummber f moles = mass  / molar mass

Molar mass = mass  / Number of moles

Molar mass = 44.7 / 1.227

Molar mass =  36.43 g/mol

Molar mass of gas X = Molar mass of H + Molar mass of X

36.43 = 1 + X

X = 36.43 - 1 = 35.43

Chlorine is the only element with molar mass approximate to 35.43

Hence X = Cl

The chemical formular = HCl