The final assembly of a bicycle usually involves attaching 2 wheels and 6 reflectors to one frame. The masses of these individual parts are as follows 1 frame (F) = 2500 g
1 wheel (W) = 1000 g
1 reflector (R) = 5 g

2. Which of the following equations best represents the building of a bicycle from packages of parts?

a) F + 2 W + 6 R → FW2R6

b) F + 2 W + 3 R2 → FW2R6

c) F + W2 + R6 → FW2R6

d) F + W2 + 3 R2 → FW2R6

3. If a company wanted to assemble a large numbers of bicycles, it might order parts by the ton rather than by the gram. Given that 1 ton = 909,000 grams

Calculate the number of packages in 2500 tons of frames (F)

Calculate the number of packages in 2000 tons of wheel packages (W2)

Calculate the number of packages in 10 tons of reflector packages (R2)

Calculate the number of packages in 4530 tons of bicycle packages (FW2R6)

4. Why might it be convenient to weigh packages in groups that contain the same number of packages?

5. How many packages are there in a group that has a mass in tons that is the same numerically as the mass of the individual packages in grams?

We could call this number of packages a pile. We could define a pile as a group having a mass in tons that is numerically equal to the mass of the individual package in grams.

6. If a bicycle company wanted to build 1 million bicycles,

How many piles of frame packages (F) would it require?

How many piles of wheel packages (W2) would it require?

How many piles of reflector packages (R2) would it require? Remember that 1 bicycle requires 6 reflectors.

7. What would be the mass in tons of each of the above number of piles?

8. How many tons of bicycles could be assembled from 2500 tons of F, assuming you had enough wheels and reflectors?

9. How many tons of bicycles could be assembled from 3500 tons of W2, assuming you had enough frames and reflectors?

10. How many tons of bicycles could be assembled from 25 tons of R2, assuming you had enough frames and wheels?

11. How many tons of bicycles could be assembled from 2500 tons of F, 3500 tons of W2, and 25 tons of R2?

How many bicycles is this?

The production of ammonia involves the reaction of one nitrogen molecule, N2, and 3 hydrogen molecules, H2, to form 2 ammonia molecules NH3. The masses of the individual atoms are as follows

1 nitrogen atom (N) = 14.01 amu
1 hydrogen atom (H) = 1.01 amu

12. What are the masses of these molecules in amu?

N2 =
H2 =
NH3 =

What do the subscripts in the above formulas represent?

To assemble 2 ammonia molecules requires 1 nitrogen molecule and 3 hydrogen molecules.

13. Which of the following equations best represents the reaction of nitrogen and hydrogen to form ammonia?

a) N + 3H → NH3
b) N + H3 → NH3
c) N2 + 3 H2 → 6 NH
d) N2 + H2 → NH3
e) N2 + 3 H2 → 2 NH3
If a company wanted to assemble large numbers of ammonia molecules, it might order parts by the gram rather than by the amu.

14. Given that 1 amu = 1.66 × 10-24 grams

Calculate the number of molecules in 28.02 grams of nitrogen (N2)

Calculate the number of molecules in 2.02 g of hydrogen (H2)

Calculate the number of molecules in 17.04 g of ammonia (NH3)

15. What can be said about the numbers of molecules in groups of molecules that have masses that are in the same ratios as the masses of the individual molecules?

16. Why might it be convenient to weigh molecules in groups that contain the same number of molecules?

17. How many molecules are there in a group that has a mass in grams that is the same numerically as the mass of the individual molecules in grams?

We could call this number of molecules a mole (from the Latin word for pile). We could define a mole as a group having a mass in grams that is numerically equal to the mass of the individual molecules in amu.

18. If a chemical company wanted to make 1 × 1024 ammonia molecules,

How many moles of nitrogen (N2) would it require? (Remember that 2 ammonia molecules can be made from each nitrogen molecule).

How many moles of hydrogen (H2) would it require? (Remember that 2 ammonia molecules can be made from 3 hydrogen molecules).

19. What would be the mass in grams of each of the above number of moles?

21. How many grams of ammonia could be made from 64 grams of N2, assuming you had enough H2?

22. How many grams of ammonia could be made from 7 grams of H2, assuming you had enough N2?

23. How many grams of ammonia could be made from 64 grams of N2 and 6 grams H2?

How many molecules of ammonia is this?