My question is about chemistry

Question

Gaseous methane reacts with gaseous elemental sulfur to produce gaseous carbon disulfide and hydrogen sulfide gas.

(a) Write the balanced chemical equation. Hint: What is the formula of elemental sulfur?

(b) If 6.20 g of methane and 2.90 g of sulfur are sealed in a 1.00 L vessel, what mass of hydrogen sulfide will be produced if the final temperature is 129.0 °C? Assume 100% yield.

(c) What are the (i) mole fractions, (ii) partial pressures (in bar), and (iii) root-mean-square speed of all gaseous species in the reaction vessel at the end of the reaction (129.0 °C)?

Answer 1

The formula for elemental sulfur is S₈

(a) 2CH₄ + S₈ ==> 2CS₂ + 4H₂S ... balanced equation

(b) mols CH₄ = 6.20 g x 1 mol / 16 g = 0.3875 mols

mols S₈ = 2.90 g x 1 mol / 257 g = 0.0113 mols

mass H₂S = 0.0113 mols S₈ x 4 mols H₂S / 1 mol S₈ x 34 g/mol = 1.53 g H₂S formed

mass CS₂ = 0.0113 mols S₈ x 2 mol CS₂ / 1 mol S₈ x 76 g/mol = 1.72 g CS₂ formed

(c) 2CH₄ + S₈ ==> 2CS₂ + 4H₂S

.....0.3875.....0.0113........0.............0..........Initial

....-0.0226....-0.0113......+0.0226..+0.0452...Change

...0.365...........0.............0.0226........0.0452....Equilibrium

Total moles at equilibrium = 0.365 + 0.0226 + 0.0452 = 0.433 mols

(i) mol fractions X:

X_CH4 = 0.365 / 0.433 = 0.843

X_S8 = 0

X_CS2 = 0.0226 / 0.433 = 0.0522

X_H2S = 0.0452 / 0.433 = 0.104

(ii) PV = nRT

P_t = nRT/V = (0.433)(0.08315 Lbar/Kmol)(402K) / 1 L = 14.5 bar total pressure

partial pressures:

CH₄ = 0.843 x 14.5 = 12.2 bar

S₈ = 0 bar

CS₂ = 0.0522 x 14.5 = 0.76 bar

H₂S = 0.104 x 14.5 = 1.51 bar

(iii) root mean square velocities:

Use u = root mean square velocity = square root (3RT/M)where...

R = 8.314 kgm²s^-2/Kmol

T = temp in Kelvin (402)

M = molar mass in kilograms

I'll let you do the math. It's just plug and chug. Good luck.