The volume composition of air at sea level has been reported to be as follows: nitrogen 78.084%; oxygen 20.9476%; argon 0.934%; carbon dioxide 0.0314%; neon 0.001818%; methane 0.0002%; helium 0.000524%; krypton 0.000114%; hydrogen 0.5%; xenon 0.87%; ozone 0.7%; nitrogen dioxide 0.2%; and iodine 0.1%. , compute the molar mass of air, in [kg/mol] based on this composition.

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g

what is the general relationship between a galaxy's distance from earth and its speed?

the answer is:

the farther away a galaxy is from us, the faster it is moving away from us.

it would be d. henry moseley

hope this !

and sorry if i'm late. have a good rest of your day! : d