Avogadro’s Number made easy!

1. How do you count large numbers of atoms and molecules?
2. What is a mole?
3. How many things are in a mole?
4. What is Avogadro’s number?

1. What is a mole used for?
2. What is Avogadro’s number?
3. Given 3.5 moles of cobalt, what is its molar mass?
4. Given 5 moles of zinc, what is its molar mass?
5. Given 10 moles of phosphorus, what is its molar mass?
6. You have 400 grams of manganese, how many moles do you have?
7. You have 250 grams of manganese, how many moles do you have?
8. You have 70 grams of lithium, how many moles do you have?

Due 2/18: practice problems 1-3, pg 311 practice problems 4, page 312
11.1 assessment 5-8, page 312
Due 2/19: practice problems 12 a-d, page 316 practice problems 14 a-e, page 318
Due 2/22: practice problems 27-29, page 323 practice problems 30 a-e, page 324

1. Given 12 moles of chromium, what is its molar mass?
2. You have 1000 grams of strontium, how many moles do you have?
3. Given 25 moles of water, what is its molar mass?
4. You have 500 grams of NaOH how many moles do you have?
5. Given 50 moles of MgCl
2
, what is its molar mass?
6. You have 200 grams of Mn
2 you have?
Se, how many moles do

1. What is the mass of sulfur if you have 2.3 x 10 24 atoms of sulfur.
2. What is the mass of carbon if you have 5.6 x 10 24 atoms of carbon.
3. What is the mass of iron if you have 1.8 x 10 23 atoms of iron.
4. What is the mass of fluorine if you have 12.9 x
10 22 atoms of fluorine.
5. What is the mass of chlorine if you have 6.7 x
10 21 atoms of chlorine.

1. What is Avogadro’s number?
2. Given 3.5 moles of cobalt, what is its molar mass?
3. You have 250 grams of manganese, how many moles do you have?
4. You have 200 grams of Mn
2 do you have?
Se, how many moles
5. What is the mass of fluorine if you have 12.9 x
10 22 atoms of fluorine.

Please write Lewis Dot Structures for the following:
1. Carbon
2. Nitrogen
3. Argon
4. Iron
5. Copper

1. Calculate the percent composition for the following: NaHCO
3
.
2. Given 200 grams of the above compound, what is the mass of each element?
3. Calculate the percent composition for the following: H
2
SO
3
.
4. Given 200 grams of the above compound, what is the mass of each element?
5. Calculate the percent composition for the following: H
2
S
2
O
8
.
6. Given 200 grams of the above compound, what is the mass of each element?

Balance the following equations and identify the type of chemical reaction involved:
____ ZnCl
2
+ ____ KOH  ____ Zn(OH)
2
____ Ba(OH)
2
 ____ BaO + ____ H
2
O
+ ____ KCl
____ K + ____ H
2
O  ____ KOH + ____ H
2
____ NaBr + ____ Cl
2
____ MgCO
3
 ____ NaCl + ____ Br
2
 ____ MgO + ____ CO
2
____ ZnCl
2
+ ____ KOH  ____ Zn(OH)
2
+ ____ KCl

People have all kinds of ways of packaging things. Eggs come in dozens
And paper comes in reams

No one knows why hot dogs come in packs of
10 and buns come in packs of 8!

Chemists even have a standard way to package atoms. Because atoms are so small the number of atoms per package is very large.

The standard container for atoms holds 6.022
X 10 23 atoms. This number is referred to by chemists as Avogadro’s number for Count
Amedeo Avogadro that invented it.

Do all moles of a particular element weigh the same? No!! Larger heavier elements have a greater molar weight that smaller atoms, just like 10 bowling balls weighs more than ten marbles.

The mass (in grams) of one mole of a substance is called its molar mass . The molar mass of an element in a.m.u.’s is the same as its molar weight in grams.

• For example, carbon’s atomic mass is 12.01 a.m.u.’s while its molar weight is 12.01 grams.

You work in a candy store and receive a new shipment on gum balls. You are asked to put them in bags of ten. The total weight of the candy is 10 kg’s. If each gum ball weighs 20 grams, how many bags do you need?

• 10 kilograms is 10,000 grams. Each gumball weighs 20 grams, so 10,000/20 = 500 gumballs. Each bag will hold 10 gumballs so you’ll need (500/10) or 50 bags to pack all the gumballs.

You have 5.5 moles of iron. The molar mass of iron is 55.85 g/ mol Fe. What is the mass of the iron that you have?

5.5 moles Fe X 55.85 g/mole Fe = 307 g Fe
1 mole Fe

Convert the following into weight in grams:
1. 2.50 moles of sulfur, S
2. 1.80 moles of calcium, Ca
3. 0.50 mole of carbon, C
4. 3.2 moles of copper, Cu

Given 352 grams of Fe iron), how many moles of iron do you have?

352 g Fe X 1 mole Fe = 6.30 moles Fe
55.85 g Fe