# MOLES!!! by 8VdW3t

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```									MOLES!!!

•   more molar ratios
•   mass – mass conversions
MOLES!!!

6.02 X 1023
MORE MOLES!!!

6.02 X 1023
MOLES 4LIFE!!!

6.02 X 1023
MASS - MASS CONVERSIONS
Mg + O2  MgO

If I start out with 50 grams O2, then how
many grams of MgO will I produce?

What problems do I face here?
•I need to convert from reactants to products!
•Equation is not balanced!
•Coefficients represent moles, not grams!
MASS - MASS CONVERSIONS
If I start out with 50 grams O2, then how many grams of
MgO will I produce?

STEPS
1.   Balance the equation         1.   __Mg +__O2 __MgO

2.   Convert grams to moles       2.   50g O2 = ? mol O2

3.   Examine mole ratios          3.   ? mol O2  ? mol MgO
4.   Convert to desired units     4.   ? mol MgO  ? g MgO
(moles to grams)
1) Balance the equation

__Mg +__O2 __MgO
2      1     2

2) Convert grams to moles
3) Examine mole ratios
4) Convert to desired units (moles to grams)
1) Balance the equation
2) Convert grams to moles
50g O2 = ? mol O2
•How do you convert from grams to moles???
•Find the MOLAR MASS!
•1 mol O2 = 2(16.00)g = 32.00g
•Now let’s solve the equation…

• 50 g O2 |           1 mol O2             | 1.56 mol O2
|           32.00 g O2           |
3) Examine mole ratios
4) Convert to desired units (moles to grams)
1) Balance the equation
2) Convert grams to moles

3) Examine mole ratios
1.56 mol O2  ? mol MgO

Balanced Equation: 2 Mg + 1 O2  2 MgO
1 mol O2  2 mol MgO

Now let’s convert moles of oxygen into moles of
magnesium oxide!

•1.56 mol O2|             2 mol MgO | 3.12 mol MgO
|             1 mol O2 |
4) Convert to desired units (moles to grams)
1) Balance the equation
2) Convert grams to moles
3) Examine mole ratios

4) Convert to desired units
3.12 mol MgO  ? g MgO
•How do you convert from moles to grams???
•Find the MOLAR MASS!
•1 mol MgO = 24.31 + 16.00 g = 40.31g MgO

•Now let’s solve the equation…
• 3.12 mol MgO |   40.31g MgO         | 125.77g MgO
|   1 mol MgO          |
MASS - MASS CONVERSIONS
If I start out with 50 grams O2, then how many
grams of MgO will I produce?

2 Mg + 1 O2  2 MgO
50 g O2 |   1 mol O2     | 1.56 mol O2
|       32.00 g O2   |

1.56 mol O2|    2 mol MgO    | 3.12 mol MgO
|    1 mol O2     |

3.12 mol MgO |     40.31g MgO    | 125.77g
MgO
| 1 mol MgO      |
MORE MOLAR RATIOS

Gases:
 1 mole of ANY gas =
22.4L in volume at STP
(standard temperature & pressure)

1  mol CO2 = 22.4 L
 1 mol O2 = 22.4 L
 1 mol H2 = 22.4 L
SOLVE…
1)   What is the volume of 2.7 mol CO2?
   2.7 mol    | 22.4L    | 60.48L
| 1 mol    |

2)   A balloon is filled with 5L oxygen gas.
How many moles is this?
   5L   | 1 mol     | 0.22 mol
| 22.4L     |
MORE MOLAR RATIOS
MOLARITY
 Used to refer to
concentration of
solutions (usually in
water)

   # moles
liters
A 1.0 molar (1.0M) solution has 1 mole/L
A 5.0M solution has 5.0 moles/L
SOLVE…
1)       If you measure out 0.55L of a 6M solution of HCl, how
many moles of HCl do you have?
     0.55L | 6 mol | 3.3 mol
|1 L    |

2)       If you need 0.7 mol NaOH for a reaction, how many
liters do you need to take from a 3M solution?
     0.7 mol       |   1 L     | 0.23 L
|   3 mol   |

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