A student conducts the chemical reaction shown below and begins with 10. mL of 0.200 M Nal and 10. mL of 0.100 M Pb(NO3)2. Which of the following is true concerning the completed reaction? The initial molarity of nitrate, NO3 - , is 0.100 M
The final molarity of the lead II ion, Pb^ 2+, is less than the initial molarity
The initial and final molarity of the sodium ion changes from 0.200 M to 0.100 M
The initial and final molarity of the iodide ion, I -, is 0.200 M.

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

14 days is the half-life of phosphorus-32

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.

how important do you think an instrument is to the musician who plays it?