Chemistry Reference
In-Depth Information
14. How many moles of molecules would 3.50 × 10
24
molecules represent?
15. How many moles would 57.5 dm
3
of hydrogen gas at STP represent?
16. How many atoms of carbon could be found in 5.00 g of this element?
17. What would be the mass of 4.56 × 10
23
water molecules?
18. How much space would 39.9 g of nitrogen gas occupy at STP?
19. What would be the mass of a 33.5 dm
3
sample of O
2
at STP?
20. How many molecules of carbon dioxide gas would occupy 10.0 dm
3
at
STP?
Part III—Stoichiometry
Base your answers to questions 21-23 on the following balanced chemi-
cal equation. Assume all gas volumes are at STP.
C
3
H
8
+ 5O
2
3CO
2
+ 4H
2
O
propane + oxygen
carbon dioxide + water
21. How many dm
3
of oxygen at STP would be required to react
completely with 38.8 g of propane?
22. How many dm
3
of oxygen at STP must react with an excess of
propane, in order to generate 20.0 dm
3
of carbon dioxide at STP?
23. How many grams of water can be generated from the combustion of
40.0 g of propane in an excess of oxygen?
Base your answers to questions 24-25 on the following balanced chemi-
cal equation. Assume all gas volumes are at STP.
2Mg + O
2
2MgO
magnesium + oxygen
magnesium oxide
24. How many grams of magnesium oxide can be produced if 30.0 g of
magnesium are allowed to react with 12.0 dm
3
of oxygen gas at STP?
25. How many grams of magnesium oxide can be produced if 25.0 g of
magnesium are allowed to react with 28.0 g of oxygen?
