Worksheet #21     Practicing mole calculations                               Name ________________________

Reference pages: pg 80-85                  Vocabulary: mole, Avogadro’s number, atomic mass, molar mass

 

Show your work.    Remember significant figures! 

1 mole = 6.02 x 1023      1 mole of any atom weighs its atomic weight in grams

 

1.   Using the average atomic masses listed in your text, Calculate how many moles of each element the following masses represent.

 

a) 19.5g platinum                                                                  b) 11.78g cobalt

 

 

 

c) 2.395g titanium                                                                 d) 86.2g sodium

 

 

 

 

e) 1.00kg barium                                                                   f) 1.00 x 1025 atoms  magnesium

 

 

 

 

 

2.        Using the average atomic masses listed on the inside back cover of your text, Calculate the mass in grams of each of the following samples.

 

a) 1.25 moles nickel                                                              b) 1.89 x 10-4 moles lead

 

 

 

c) 2.6 x 107 moles aluminum                                                d) 0.45 moles barium

 

 

 

 

 

e) 3.01 x 1023 atoms of sodium                                            f) 1.24 x 1024 atoms of iron

 

 

 

 

3.        How many atoms are in each of the following samples? 

 

a) 0.000259 mol of platinum                                                b) 4.40 mol of tungsten

 

 

 

c) 0.000259g of platinum                                                     d) 2.89g of gold

 

 

 

 

e) 2.0 lb of magnesium                                                         f) 2.00 kg of magnesium

 

 

 

4.  What mass of carbon contains the same number of atoms as 1.008g of hydrogen?

 

 

 

 

 

5.   What mass of oxygen contains the same number of atoms as 14.01g of nitrogen?

 

 

 

 

 

6.    What mass of nitrogen contains the same number of atoms as 48g of oxygen?

 

 

 

 

 

7.    Which weighs more, 1 mole of helium atoms or 0.5 mole of carbon atoms?

 

 

 

 

 

8.  There are 50 billion gold atoms in every drop of sea water!  (1 drop = 0.05ml)  Is it feasible to "mine" the ocean for gold?  In other words, how many gallons of sea water would have to be stripped of its gold to produce 1 troy ounce of the precious metal, now worth $528.  (1 troy ounce is 31.1g)