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Name: ___________________________

Mods: _______________

Unit Ten:

Introducing…..

The Mole!

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Chemistry: Dr. Wilhelm & Ms. Greendyk

What’s a Mole?

The mole is a unit of _________________.

Just like meters tells us _________ and seconds tell us how much _________,

the mole measures an _______________ (how much).

Units of measure similar to mole include: Dozen =_____________

Ream = _____________

Mole = ______________

Chemistry and the unit Mole

Why do chemists use the unit mole?

1. The unit mole is based on Avogadro’s number which is equal to__________. This number is very, very ___________.

2. Atoms and molecules are very, very _________.

3. Since the atoms and molecules are ________, we need _________ unit to describe them.

For this reason, the unit ____________ is mostly used in chemistry.

Silly Facts about the unit Mole:

1. A mole of jelly beans: If we covered the entire U.S. with jelly beans (each with 1 cm3 of volume), the U.S. would be under a layer of jelly beans almost 40 miles thick!

2. A mole of pennies: If an Avogadro number of pennies were distributed evenly among the 4.9 x 109 human inhabitants of earth, each man, woman, and child would have enough money to spend a million dollars every hour-day and night-and still have over half of it unspent at death.

3. Can you find another fun analogy?

Unit Conversions:

Using dimensional analysis (you’ll need this skill to do our activities!)

Determine the final label by crossing out the units that cancel:

1) mi x hr x min x m x cm =

hr min s mi m

2) m x s x min x ft =

s min hr m

3) L x ml x g x kg x kg =

Ml kg L ml g

Use the following equivalents to complete the conversions: be sure to show your work!

100 cm = m 1760 yd = 1 mi

1 in = 2.54 cm 1000 m = 1 km

12 in = 1 ft .62 mi = 1 km

3 ft = 1 yd

Convert 3.0 centimeters to feet

Convert 24.5 inches to yards

Convert 110 yards to kilometers

Activity: How big is a Mole?

A mole is 6.02 x 1023 of anything. A mole of donuts is 6.02 x 1023 donuts, and a mole of basketballs is 6.02 x 1023 basketballs—and that’s a lot of basketballs! A mole of basketballs would just about fit into a ball bag the size of the Earth! So just how big is a mole? That’s what we’re going to find out.

When your teacher instructs you to do so (and not before!), spend exactly one minute making dots in the box below, as many dots as you can make in a minute.

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Now, count the dots. (A highlighter or differently-colored pen may be useful.) What is your dot making rate in dots/minute? _____________

a. Working at this rate, how many dots could you make in an hour? _____________________

show your work here:

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|______ dots |60 minute |______ dots/hr |

| minute |1 hour | |

In a year? ___________________________

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|_______ dots |24 hours |365 days |_____ dots/yr |

| hour |1 day |1 year | |

So how long would it take you to make a mole of dots? That’s 6.02 x 1023 dots!

a. Determine your rate as moles (6.02 x 1023 dots) per year

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|________ dots |1 mole |________ mole/year |

| years |6.02 x 1023 dots | |

b. Let’s see how many years will it take to make a moles worth of dots!

|1 mole |1 year |_______________ years |

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| |___________ moles | |

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How many moles of chalk does it take to write your name?

Background: chalk is a chemical called calcium carbonate (CaCO3)

Procedure:

1. Measure the mass of a piece of chalk and write that value in the data table.

2. Go to the board and write your name using the same piece of chalk

3. Record the new mass of the chalk, after using it at the board.

4. Calculate the mass of chalk used to write your name and follow the “mole road” to determine the number of atoms used.

Data Table:

|Mass of chalk before |grams |

|Mass of chalk after |grams |

| Mass of chalked used |grams |

Calculations:

|_______Grams CaCO3 |I mole |________atoms |

| | |I mole |

| |_______Grams CaCO3 | |

Conversions using mole mass:

The unit mole now allows us to relate ___________________ to ___________________. This is important since atoms are so ________________, we can use the unit mole to obtain tangible _______________________.

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1. _____________ _______________ describes how many grams in one mole of an element or compound. It is determined just like ___________ ___________. We add the mass of all the contributing elements. This information is found on the __________________ ________________ .

2. When converting mass to moles we _____________ by the molar mass.

3. When converting moles to mass we ______________ by the molar mass

Sample problems:

1. Calculate the molar mass of sodium hydroxide (NaOH)

Na:

O:

H:

2. Convert 226g of NaOH to moles: =

3. Convert 1.4 moles of NaOH to grams: =

4. Convert 28.0 grams of NaOH to moles: =

Conversions using Moles:

(mole road)

Example Calculations (with dimensional analysis):

1. Grams ( Moles

Find the number of moles in 92.2 g iron.

2. Moles ( Grams

Calculate the mass, in grams, of 0.250 moles of sodium.

3. Moles ( Atoms

Calculate the number of atoms in 3.2 moles of carbon.

4. Grams ( Atoms

Calculate the number of atoms in 2.5 grams of silver.

Mole Maze!

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The earth is 4.5 billion years old.

(4,500,000,000 yrs.)

You’d be making dots for longer than the earth has existed and still not be done!

Step 2: Calculate the molar mass of CaCO3 and put it here.

Step 4: Answer here!

Step 1:

Mass of chalk used goes here.

Step 3: Avogadro’s number goes here.

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