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44 votes
44 votes
Which of the following gas samples have the greatest average molecular speed at 25°C?

A) Kr
B) CH4
C) N2
D) CH2CI2
E) CO2

User Claudiu Creanga
by
3.1k points

2 Answers

22 votes
22 votes
  • Average Molecular Speed be V

We know


\boxed{\sf V\propto T}


\boxed{\sf V\propto (1)/(m)}

  • m is molar mass
  • Temperature is constant for all.
  • So lower the molar mass higher the average molecular speed

Lets find one by one


\\ \tt\hookrightarrow Kr=83.7g/mol


\\ \tt\hookrightarrow CH_4=16g/mol


\\ \tt\hookrightarrow N_2=28g/mol


\\ \tt\hookrightarrow CH_2Cl_2=86g/mol


\\ \tt\hookrightarrow CO_2=44g/mol

  • Lowest is METHANE(CH_4)

Option B is correct.

User Tweetysat
by
2.8k points
30 votes
30 votes

Answer:

B) Methane, CH4

Step-by-step explanation:

» For a molecule to have a great molecular speed, it mas have less molecular mass.

• From the samples given,

  • Kr → 83 g
  • CH4 → 12+(4×1) → 16 g
  • N2 → (2×14) → 28 g
  • CH2Cl2 → 12+2+(35.5×2) → 85 g
  • CO2 → 12+(16×2) → 44 g


{}

User Manoj Sreekumar
by
3.1k points