Air is 23.19% o2 and 75.46% n2 by weight) would be needed to burn a pound of gasoline by a reaction whereby c8h18 reacts with o2 to form co2 and h2o?

Approximately pounds.

Start by balancing the equation for the complete combustion of octane in oxygen:

Thus it would take molecules of oxygen to completely react with molecules of octane. Oxygen and octane thus react at a ratio of

to

Given the molar mass of the species:

The mass ratio between the two species when the combustion proceeds to completion would thus equal:

to

It would thus take

to combust completely one pound of octane.

Apply the mass ratio stated in the question:

not clear

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