The density of an unknown gas at 98°C and 740 mmHg is 2.50 g/L. What is the molar mass of the gas with work showed?

78.2 g/mol

Step-by-step explanation:

We can use the Ideal Gas Law to solve this problem:

pV = nRT

Since n = m/M, the equation becomes

pV = (m/M) RT Multiply each side by M

pVM = mRT Divide each side by pV

M = (mRT) / (pV)

dа ta:

ρ = 2.50 g/L

R = 0.082 16 L·atm·K⁻¹mol⁻¹

T = 98 °C

p = 740 mmHg

Calculation:

(a) Convert temperature to kelvins

T = (98 + 273.15) = 371.15 K

(b) Convert pressure to atmospheres

p = 740 * 1/760 = 0.9737 atm

(c) Calculate the molar mass

Assume V = 1 L.

Then m = 2.50 g

M = (2.50 * 0.082 06 * 371.15) / (0.9737 * 1)

= 76.14/0.9737

= 78.2 g/mol