1. It’s really helpful, not just a way to
make you cry.

2. What do the 4, 3 and the 2 as coefficients mean ???
A) They are MOLE ratios.
B) They are GRAM ratios
C) They are atom, molecule and FU ratios.
D) They are liter ratios.
E) All of the above.
F) Only A and C
G) Only A, C, and D
The coefficients of a balanced
chemical equation are MOLE
ratios, atom-molecule-FU ratios, or
Liter ratios. CHOICE G!

3. If you have 40 atoms of Fe and 90 molecules of O2 ….
20
Then you can make _______________ FU’s of the product.
iron
What is the limiting reactant? _______________
60
How much of the reactant in excess is LEFT OVER? ______

4. If you have 12 atoms of Fe and 6 molecules of
oxygen then you
can make _______________ FU’s of ferric
oxide.

5. If you have 400 atoms of Fe and 300 molecules
of oxygen then you
can make _______________ FU’s of ferric
oxide.
Weird problem – BOTH are the limiting reactant
and you run out of both of them simultaneously !!

6. If you have 9 moles of Fe and 6 moles of
oxygen then you
can make _____________ MOLES of ferric
oxide.

7. If you have 405 moles of Fe and 300 moles of
oxygen then you
can make _______________ moles of ferric
oxide.

8. If you have 4 moles of EACH reactant.
HOW MANY MOLES OF THE REACTANT
INXS WILL BE LEFT OVER?

9. If you have 12 moles of Fe and 15 moles of oxygen
how much OXYGEN will be left over after the
reaction is complete? __________
And, how much product can you
make?__________

10. Get your calculator ready. SHOW WORK
If you have 100 grams of iron and 100 grams of
oxygen how much product can you make?
100 g OX x 1 mole OX x 2 mole product x 160g product
1 32 grams OX 3 mole OX 1 mole product
100 g Fe x 1 mole Fe x 2 mole product x 160g product
1 56 grams Fe 4 mole OX 1 mole product
That emphasis means 142 is the
answer !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

11. Now we know, from the last slide that if you have
100 grams of each reactant only 142 grams of
product are made. Since iron was the limiting
reactant, how much of our 100 grams of oxygen is
USED UP? ______________
How much of the oxygen is LEFT OVER?
_______________