Four identical 1.0-L flasks contain the gases He, Cl2, CH4, and NH3, each at 0°C and 1 atm pressure. For which gas do the molecules have the highest average velocity? a) He
b) Cl2
c) all gases the same
d) NH3

a) He

Explanation:

The formula of average velocity of a gas, v, is:

Where R is gas constant, T is temperature and M is molecular mass of the gas.

As you can see in the formula, the gas with the lowest molecular mass will be the gas with highest average velocity.

Molecular mass of He is 2g/mol; Cl₂ = 70g/mol; NH₃ = 17g/mol.

That means the gas with the highest average velocity is:

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g