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WS - Moles and Molar Mass

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					Name: ______________________________________________ Date: _________________Period:_____
                                   Chemistry Worksheet
           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
   the compound.
                   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 _________
                    of product.

				
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