Name: ______________________________________________ Date: _________________Period:_____
Moles and Molar Mass
1. In chemistry, the “____________” is the standard unit that indicates ____________________
2. A mole is the amount of a substance that contains as many particles as there are atoms in exactly
_________________________________________, which is ________________________.
3. This is ____________________ Number – _______________________________________
NOTE: This number can always be reduced and rounded to the correct number
of significant figures.
4. The mass of one mole of a pure substance is called the ___________________ of that substance.
5. A molar mass of an element contains _____________________________________________.
List three examples:
6. A mole is the amount of a substance that contains ___________________________________.
7. What is the approximate mass of one mole of helium atoms? - __________ g.
8. The mass of one mole of a pure substance is called the ___________________ of that substance.
9. Molar mass is usually written in units of ________________________.
10. Sample Problem - to two decimal places, what is the relative atomic mass and the molar mass of the
element chlorine, Cl?
11. Sample Problem - determine the mass in grams of 3.00 mol of sulfur.
12. Sample Problem - determine the mass in grams of 3.01 × 1023 atoms of fluorine
13. Sample Problem - determine the number of moles in the following: 12.15 g calcium
14. Sample Problem - determine the number of moles in the following: 1.50 × 1023 atoms bromine
15. Sample Problem - determine the number of atoms in the following: 2.50 mol iron
16. Sample Problem - determine the number of atoms in the following: 1.50 g phosphorus
17. The molar mass of an element is numerically equal to ________________________________
Example) The molar mass of lithium (Li) is __________________________.
Example) The molar mass of mercury (Hg) is ________________________.
18. The molar mass of a compound is numerically equal to the sum of the atomic masses of the element in
Example) The molar mass of H2O is __ x _____ + __ x _____ = ____________.
Example) The molar mass of CO2 is __ x _____ + __ x _____ = ____________.
19. Recall that the Law of Conservation of Mass tells us that, in ordinary physical or chemical changes,
____________________________________________, only ________________________.
20. This is the reason why chemical equations must be _______________, so as to ensure that we
have _____________________________ in our products as we started with in our reactants.
21. Consider the following scenario in which we start with a certain amount of mass: hydrogen gas and
oxygen gas react to produce water.
Write the chemical equation:
If we start with a total of 100g of reactant, we must produce a total of _________