General Knowledge - Chemistry - Discussion

Hydrogen gas with higher temperature and lower molecular weight have higher molecular speed.

Among the given gases, hydrogen at 50°C has a maximum value of T/M and the highest speed. The correct option is A.

Please explain it more clearly.

Let's solve it step- by- step:

Formula for molecular speed ( root mean square speed, urms):

Urms=√3RT/M

R=universal gas constant.
T= temperature in Kelvin.
M= molar mass (in kg/mol).

Higher t/m-higher speed. So we need to compare T/M for each gas.

Given:

A. H2 at -73⁰C _T= -73+273=200 k,M(H2)=2 g/mol = 0.002 kg/mol.
B. CH4 at 300 K_M(CH4) = 16 g/mol = 0.016 kg/mol,
C. N2 at 1,027⁰C_T=1,027 + 273 = 1300 k, M(N2) = 28 g/mol = 0.028 kg/mol,
D. O2 at 0⁰C_T=0 + 273 = 273K, M(02) = 32 g/mol = 0.032 kg /mol.

Now calculate T/M roughly:

A: 200/0.002 = 100,000.
B: 300/0.016 = 1 8,750.
C.1300/0.028 = 46,429.
D.273/0.032 = 8,531.

Result

Highest value is 100,000 for A(H2 at -73⁰C).

Thus, the Answer: A. H2 at -73⁰C.