2. Based on the same dichotomous key, what is the butterfly shown below? 天 &
1
1
Go to 2
Go to 3
II
1
2.
Hindwings pointed
Hindwings rounded
Wings mainly yellow
Wings mainly black
Wings orange with black piping
Wings yellow with black edges
Papilio glaucus
Papilio polyxenes
Danaus plexippus
Colias philodice
1
3
II.
O A Papilio glaucus
O B. Papilio polyxenes
O C. Danaus plexippus
O D. Colias philodice

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

a physical change biology

explanation: