Catalyst

1. How many dozens do you have if you have 120 pencils?

2. There are 10 millimeters in a centimeter. If I have 5 centimeters, how many millimeters do I have?

3. What is the molar mass of CaCO3?

Today’s Agenda

BIG GOAL!

Stoichiometry is a lot of little pieces Important to keep big picture in mind

A question… How many bags of chips would you have to give up to buy a video game?

WHY?

THIS GRAPHIC IS YOUR NEW BEST FRIEND! (so write it down)

What can it tell you?

2H2 + O2 2H2O

Moles

Substance A

Moles

Substance BGrams

Substance A

Grams

Substance B

Molar

Mass

Mole

Ratio

Molar

Mass

How?

We can use dimensional analysis to convert between quantities of chemicals.

Number and unit you were givenConversion Factor (unit you want)

Conversion Factor (unit you were given)

Today’s Agenda

Grams to Moles

Today, we will start off with the first part of the graphic. Going from grams of a substance, to moles of the same substance. We use the same steps for dimensional analysis that we did yesterday.

Moles

Substance A

Moles

Substance BGrams

Substance A

Grams

Substance B

Molar

Mass

GRAMS TO MOLES

Grams to Moles:

1. Find the molar mass of the compound Example: For H2O, 18 g/mol is the same thing as 18g = 1 mol.

2. Use the molar mass as a conversion factor

Grams to Moles Example

How many moles of CaCO3 are there in 145 grams of CaCO3

Step 1: What is the molar mass of CaCO3?

Step 2: Use the molar mass as a conversion factor

Grams to Moles Example 2

How many moles of CCl4 are there in 265 grams of CCl4?

CHECK IN PRACTICE

In your notes, try the next two problems silently and by yourself:

1. How many moles of CO2 are there in 86 grams of CO2?

2. How many moles of CaCl2 are there in 100 grams of CaCl2?

Moles to Grams Example 3

How many grams of NaCl are there in 6 moles of NaCl?

(Backwards! But still find the molar mass.)

CHECK IN PRACTICE

In your notes, try the next problem silently and by yourself:

1. How many grams of ZnO2 are there in 5 moles of ZnO2?

Today’s Agenda

CHECK IN PRACTICE

1. How many grams of NO3 are there in 4.2 moles of NO3?

2. How many grams of LiBr are there in 3.7 moles of LiBr?

3. How many moles of LiBr are there in 112 grams of LiBr?

4. How many grams of BeF2 are there in 4 moles of BeF2?

5. How many moles of BeF2 are there in 150 grams of BeF2?

Today’s Agenda

Exit Slip

1. What, in general, is the conversion factor when going from grams to moles?

2. How many moles of H2O are there in 100 grams of H2O?