chemical quantities 10.1 the mole: a measurement of matter

Chemical Quantities

10.1 The Mole: A Measurement of Matter

• Do Now

What is 4.2 x 105 x 6.6 x 103

• Objective – Counting and the Mole We will spend two days on this lesson

• HW Pg. 296 # 9-15 (Start each problem)

What is 4.2 x 105 x 6.6 x 103

= 2772000000.

= 2.8 x 109

Measuring Matter

• Common methods of measuring– Count

– Mass

– Volume

What is a Dozen?

What is Dozen?

• A dozen is 12 of something we need to start thinking of the something as a representative particle

What is a Mole?

What is a Mole?

• A mole = 6.02 x 1023 representative particles

• A mole of any substance contains Avogadro’s Number of representative particles.

Converting with the mole

• How many dozen eggs is 136 eggs?

Converting with the mole

• How many dozen eggs is 136 eggs? 136 eggs * 1 dozen = 11.33 dozen

12 eggs

Converting with the mole

• How many dozen eggs is 136 eggs? 136 eggs * 1 dozen = 11.33 dozen

12 eggs• How many mole is 2.80 x 1024 atoms of

silicon?

Converting with the mole

• How many dozen eggs is 136 eggs? 136 eggs * 1 dozen = 11.33 dozzen

12 eggs• How many mole is 2.80 x 1024 atoms of

silicon? 2.80 x 1024 atoms * 1 mole = 4.65 mol Si

6.02 x 1023 atoms

• Do Now - How many representative particles of iron do you have if you have 2.5 moles of Iron? What is the representative particle?

• Objective –Molar Mass Finish assignment from last night

Pg. 296 # 9-15

• Do Now - What is the molar mass of C3H8?

• Objective – 10.2 Mole Mass and Mole Volume Relationships

• HW Pg 303 # 26 – 31

The Mass of a Mole of an Element

What is the mass in grams of the sample of iron you have from the previous question?

The Mass of a Mole of an Element

• The atomic mass of an element expressed in grams is the mass of a mole of the element.

• So what about the molar mass of a compound?

The Mass of a Mole of a Compound

• What is the mass of a mole of H2O2?

The Mass of a Mole of a Compound

• What is the mass of a mole of H2O2?

H + H + O + O 1.01 + 1.01 + 16.00 + 16.00 = 34.02grams

Chemistry and Snow

10.2 Mole to Mass and Volume

• The Mole Mass Relationship

Mass (g) = number of moles x mass (g) 1 mole

• The Mole Mass Relationship

Mass (g) = number of moles x mass (g) 1 mole

What is the mass of 3 moles of NaCl?

Mass (g) = number of moles x mass (g) 1 mole

Mass (g) = 3.00 moles NaCl x 58.5 (g) 1 mole NaCl

= 176 g

• The Mole Volume Relationship At STP, 1 mole or 6.02 x 1023 representative particles, of any gas occupies a volume of

22.4L

Molar Volume = 22.4 L

10.1 Homework Review

• Pg. 296 #9-159. By count, mass, and volume10. One mole of any substance contains Avogadro’s number (6.02 x 1023) representative particles11. The molar mass on any element is its atomic mass expressed in grams12. Add together the masses, expressed in grams, of each element in one mole of the compound13. 2.49 x 10-1 mol NH3

14. 5.27 x 1024 atoms 15. 136.2 grams/mole

10.1 and 10.2 Practice

1. Calculate the molar mass of the following a. Br b. H3PO4

2. How many moles are in 15.5 g of SiO2?

3. Find the mass of 7.00 mole of H2O2.

4. Calculate the volume of 7.6 moles of Ar gas at STP. 5. Find the mass, in grams, of a single molecule of aspirin ( C9H8O4).

6. Find the number of atoms in 5.78 mol NH4NO3.

10.3 Percent Composition

The relative amounts of the elements in a compound

• Do Now – What is the percent composition by mass of propane (C3H8)?

• Objective – Review Percent Composition

• HW – Pg. 312 # 43-46

• Do Now – What is the mass of a room filled with O2, if the room has the dimensions 2.5m x 4m x 4m? This is about the size of a dorm room.

(1 liter = 0.001 cubic meters) (1 gram = 0.00220462262 pounds)

• Objective – Empirical and Molecular Formulas

• HW – Pg. 312 # 43-46 Be Sure this is finished

Prelab due in two classperiods

Percent Composition as a Conversion Factor

• How many grams of Hydrogen do you have in 82.0 grams of propane (C3H8)?

Empirical Formulas

• The lowest whole-number ratio of atoms in a compound

Which of these is in the lowest whole-number ratio?

CH C2H2 C6H6

Empirical Formulas

• The lowest whole-number ratio of atoms in a compound

Which of these is in the lowest whole-number ratio?

CH

Molecular Formula

• A molecular formula is either the same or a simple whole-number multiple of its empirical formula.

Molecular Formula

• A molecular formula is either the same or a simple whole-number multiple of its empirical formula.

Notice What happens with the molar massesCH C2H2 C6H6

13 26 78

13 2(13)=26 6(13)=78

What is the molecular formula of compound whose molar mass is 60g/mol and its empirical formula is CH4N?

What is the molecular formula of compound whose molar mass is 60g/mol and its empirical formula is CH4N?

Empirical Formula Mass

CH4N= 30

Molecular Mass / EFM = Ratio

60 / 30 = 2 Molecular Formula

C2H8N2

Prelab

• Name (your name)

• Title (specific to lab)

• Purpose (1-2 sentences about why you are doing the lab )

• Procedure (list for of each step, use picture if it helps)

• Data Table (make a version of the one in the prelab handout)

• Prelab Questions (some labs have then some do not)

Mole Ratios – Copper and Silver Nitrate • Wear goggles, aprons, and gloves. These chemicals are

corrosive, strong oxidizers, toxic, and may stain skin and clothes.

• Silver Nitrate / Rinse Water / Copper • Use the same balance during the experiment• Be sure to label your 200 mL beaker (not 100mL)

before you mass it. • Discard all waste solutions at the center table.

Nothing should be poured down the sink. • The Acetone rinse beakers are at the center table. • Return your tray with all glassware rinsed and dried.

Beakers to dry in try at front. Copper in waste beaker.

Pass in take-home quiz

• Do Now - There were two sons and two fathers, they caught three fish and each got one how is this?

• Objective – Review Lab Report Format and begin work on lab reports

• HW – Lab Reports are due the second time class meets next week

Lab Report Format

• Submitted to teacher as a stapled document. No electronic submissions accepted.

• Written in the third person and in the past tense. You are writing about the science, not you.

• Professional presentation (no frillies), report does not need to be typed.

Title Page (separate page)

• Title• Submitted By: (your name) Lab Partners: (list any lab partners names,

omit if none)• Date of Submission: Due 2nd meeting next week

• Lab Section: (class section)

Purpose

• In one or two sentences clearly state the purpose. Most labs are done to explore something and some are done to test a hypothesis.

• Past tense “ The purpose of this lab was to……“

Procedure

• Write a concise account of what you actually did. May be different from your prelab procedure. Be honest, not perfect.

• Past tense• Paragraph form

“ 32 grams of NaCl dissolved in 20 mL of water in a test tube. “

Data Table(s)

• Data Table from lab session. Never recopy • Data from lab should be signed by instructor• In this case submit your entire prelab

Calculations or Analysis

• All calculations must be shown including units. Refer to the “Example of Calculations for a Lab Report” hand-out, it’s also on the wiki page. For experiments where calculations are not the end result, an explanation of the observed results should be contained in this section.

• For this lab you need to show calculations for Question– Mass of copper wire that reacted (lost in exp.) 1– Moles of copper wire that reacted 1– Mass of silver metal produced 2– Moles of silver produced 2– Determine the mole ratio rounded to whole numbers 3 # moles Ag to # moles Cu– $ 33.37 / Troy ounce - Floor price of Silver on 2/16/12 7– Calculate the current market value of the silver produced

8

Summary of Results Table • Only final calculated results that will be used

to draw conclusions about the objective of the experiment should be included in your Summary of Results Table. For experiments without calculations this section may be omitted. Summary of Results

Mass of Cu reacted

Moles of Cu reacted

Mass of Ag produced

Moles of Ag produced

Ratio of moles Ag to Moles Cu

Current Market Value of Ag produced