Chemistry 101Dr. Lucio Gelmini

Room 5-132AGelminiL@macewan.ca

497-5813http://academic.macewan.ca/gelminil

Welcome to CHEM 101Grant MacEwan University

September 2011

Welcome to Day One!

•

Textbook Tax Credit-Get your money back!

•

Your course textbook options

•

Logging into OWL for your homework

•

Accessing your e-book

Did you know that you can claim…

$65 for each month you qualify for the full-time education amount?

or…

$20 for each month you qualify for the part-time education amount?

You can claim the textbook amount (right on your tax return!) if

you are eligible to claim the education amount (and can support, with documentation, your enrolment at a post-secondary institution).

Textbook Tax Credit

YOUR COURSE PACKAGE IS AVAILABLE IN THE BOOKSTORE NOW!

•

Electronic only option: 24 month OWL access code w/ ebook, buy @ Macewan

bookstore. $69.95

•

Textbook option: Zumdahl

Chemical Principles 6ed, Student solutions manual & OWL access code w/ ebook, $144.95

•

ATTN: Dr. Llano’s sections, you will also require a Turningpoint

clicker, available at the campus bookstore.

How to Register for the OWL System

FIRST: Get an access code. Three ways to purchase: ◦

Packaged with the purchase of a new textbook

◦

Purchased separately from the book store◦

Purchased online. Go to www.cengage.com/owl

Access codes are 25 characters long and look like this: kg609-qkj3y-2kd4k-h3kvq-hv5d4

Go to: www.cengage.com/owl

How to Register

Select Your Course and Click Register

Select Your Textbook

Click on the name of your Textbook

Select Your School

Select your school from a list

Select Student Registration

Click on the blue arrow under Student Registration

Select the Course/Section you are in

Make sure you select the correct section

Complete the Form

Enter Access Code hereORChoose the 14 day trial

Confirm info and click continue

Agreement

Click I AGREE after reading.

Complete the registration process…

At the successful registration page, choose the Login Page

Enter Login and Password

Enter Login and password you chose during registration

Click here if you’ve forgotten your password

•

If you forgot to bookmark the login page or ever need to get back to it:

•

Go to: www.cengage.com/owl–

Select your and choose Log in

–

You’ll be prompted to then choose your course and school

To Log In Throughout the Semester

Choose Your Class

Click on the class you are in

Your Course HomepageIf you used the 2 week grace period, it tracks when you must enter a code

See your current assignments

For Student Support

Click here to contact Technical Support

Got Questions!?

Come visit us!

We will be hosting student office hours for you to come and ask us questions about OWL.

•Room 7-143 Friday, September

9 10:30 AM-12:30 PM•Room 5-206 Tuesday, September

13

11:00

AM

1:00

PM

Thank You Have a Great Semester!

Goals for this class and beyond•

To develop chemical intuition and curiosity

•

To acquire the knowledge and know- how for solving chemistry problems

•

To learn how to learn, particularly in a science classroom

–Definitions

–Scientific problem solving

–Math review

–Uncertainty in measurement and significant figures

Review topics

What is chemistry?•

Chemistry is the science of matter and its transformations

•

Goals:–

to better understand the nature of matter

–

to predict and control its behavior–

to develop new combinations, processes, and applications

Scientific method•

Observations–

Qualitative, quantitative, or semi-quantitative

•

Hypothesis–

Initial opinion or guess

•

Experiments–

Rational, repeatable investigations

•

Verification/communication–

Further investigation

–

Formulation of laws, theories, and/or models

Thinking chemically•

Problem solving: repetition, practice, and experience

•

Educated guessing

•

Trial and error

Central idea in chemistry•

Macroscopic properties and behavior result from submicroscopic properties

•

Observable changes ↔

Unobservable causes

Definitions•

Matter:

has mass and volume

•

Properties: characteristics that give each substance a unique identity

–

Physical: shows these by itself withoutinteracting with another substance color, state (s, l, g), density, …

–

Chemical: substance shows these as it interacts with or transforms into other substances reactivity, flammability, …

Physical vs. chemical change

•

Physical change

Chemical Change•

Ice (solid water) → liquid water

Water

→ hydrogen + oxygen

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Physical states of matter

Example physical & chemical properties of copper

Shiny

Reddish

Malleable

Conductive

d = 8.95 g/cm3

melts at 1083°C

boils at 2570°C

slowly reacts in moist air

reacts with nitric acid

slowly forms a deep-blue solution in aqueous ammonia

Conceptual chemical reactionA + B ↔ C + D

“Reactants”

→ “Products”

“Forward”

and “reverse”

direction

•

Depending on the process or reaction:–

Energy can be absorbed or released

–

Energy change can be large or small

Examples•Chemical reaction:

Methane (natural gas) combustion releases heatCH4

(g) + 2 O2

(g) → CO2

(g) + 2 H2

O(g)

•Physical transformation:

Water boiling to form steam requires energy

H2

O(l) →

H2

O(g)

Problem Solving– Identify problem

•

Given and desired values

– Plan•

Find known relationships

– Set up•

Conversion/unit cancellation

– Calculate solution•

Number and units

Quantitative science•

Values:–

number + unit

•

Units:–

chemistry uses SI units (International System of Units) –

the metric system

•

Math:–

go through appendix 1 (math review) and 2 (units/calculations)

Exact vs. inexact numbers•

Exact:–

defined or counted

–

have as many sig.figs. as needed–

no uncertainty

–

do not limit #sig.figs. in answer

•

Inexact:–

come from measurements

–

have associated uncertainty (from measurement)–

may limit #sig.figs. in answer

Precision vs. accuracy•

Precision–

how close repeated measurements are to each other →

reproducibility

•

Accuracy–

how close measurements are to actual (real) value →

correctness

•

Precise•

Not Accurate•

Better Accuracy•

Not Precise•

Precise•

Accurate

Mass of Water

9.80

9.90

10.00

10.10

10.20

1 2 3 4 5

Trial

Mas

s (g)

Precision vs. accuracySystematic error

–

measured values are all above or below real value

–

can be corrected for (in theory)

•

Random error–

measured values are scattered above and below real value

–

can only be minimized through more precise measurement/equipment

Mass of Water

9.90

10.00

10.10

10.20

10.30

1 2 3 4 5

Trial

Mas

s (g

)

Calculations and meaning – Significant Figures

•

Number of decimal places in a reported value:–

should reflect the precision of the measurement

–

depend on scale/divisions on measuring device

1.4 cm ±

0.1 cm

to 1/10 of a cm0 1 2

1.38 cm ±

0.01 cm

to 1/100 of a cm0 1 2

Rules for Determining Significance•

All non-zero digits are significant

•

Zeroes may or may not be significant–

Leading: NOT significant 0.0023 g has 2 sig.figs.

–

Buried:

ARE significant

0.00203 g has 3 sig.figs.

–

Trailing: depends on if a decimal point is presentwith “.”

–

significant 0.00230 g has 3 sig.figs.

without “.”–

who knows? 230 g has 2 or 3 sig.figs.Choice – express/convince yourself

Examples•

3400000 mL

•

0.0004050 g•

4.050 ×

10-4

g

•

43001 s•

0.1044 km

•

15.0 cm3

•

Scientific notation removes any ambiguity:•

Example:

1000 m

–

1.000 ×

103

m

4 sig.figs.

to ±1 m

–

1.00 ×

103

m

3 sig.figs.

to ±10 m

–

1.0 ×

103

m

2 sig.figs.

to ±100 m

Calculations and significant figures•

Addition & subtraction:–

Round answer to least precise decimal place

•

Multiplication & division:–

Round answer to least number of sig.figs.

106.78 mL = 106.8

mL

83.5

mL+ 23.28 mL

863.0879 mL = 863.1

mL

865.9 mL

-

2.8121 mL

= 23.4225 cm3

=

23

cm39.2

cm ×

6.80 cm ×

0.3744 cm

Rounding•

Round at the end of all steps in a calculation–

If the digit removed is more than 5, the preceding number increases by 1, hence, 1.347 g→1.35 g

–

If the digit removed is less than 5, the preceding number is unchanged, hence,1.343 g → 1.34 g

–

If the digit removed is 5, the preceding number increases by 1 if it is odd and remains unchanged if it is even.1.345 g → 1.34 g 1.335 g → 1.34 g

Example 1

=−cm

cmcm085.7

448.13521.16 22

cmcmcm

cmcmcm 104.2

085.7904.14

085.7448.13521.16 222

==−

•

All measured #s•

Units are kept or cancelled

mmcm

mcm 02104.010104.2100

1104.2 2 =×=× −

•

Defined relationship

Example 2( )

=××

31000

14

55.111080.4

cmmg mg

g

( )316.4

55.110.48

55.111080.4

331000

14

cmgmg

g

cmg

cmmg

==××

•

Measured #s •

Defined relationship

SI Base Units

•

First 5 –

most important in this class

Base quantity Name Symbollength meter m mass kilogram kg time second s

temperature kelvin K amount of substance mole mol luminous intensity candela cd

electric current ampere A

Derived units•

Combination of base units

•

Examples:

–

Area: two dimensional “length”

m × m = m2

–

Volume: three dimensional “length”m×m×m = m3

–

Speed: length”and

time →

m / s–

Work/energy:

mass, length, acceleration

kg × m × m/s2 = = J

And so on…

Prefixes

•

Bigger than base

Smaller than base

Exponential Name Symbol1×1024 yotta Y 1×1021 zetta Z 1×1018 exa E 1×1015 peta P 1×1012 tera T 1×109 giga G 1×106 mega M 1×103 kilo k 1×102 hecto h 1×101 deka da

Exponential Name Symbol1×10-1 deci d 1×10-2 centi c 1×10-3 milli m 1×10-6 micro µ 1×10-9 nano n 1×10-12 pico p 1×10-15 femto f 1×10-18 atto a 1×10-21 zepto z 1×10-24 yocto y

•

Express huge range of values in more manageable ways

Using prefixes•

Exponential replaces prefix and vice versa

•

More coming on conversion problems

gkg 31011 ×=

mnm 91011.411.4 −×=

Using relationships in conversion problems

•

What is the price of 325 cm of copper wire that sells for $0.15/ft?

•

Find desired –

look for words like “what is”, “calculate”, “find”, …–

Target:

price ($)

•

To what is target compared –

look at other end of the “question”–

Given:

325 cm wire

•

Set up problem to cancel units –

Price:

in $

Length: in cm

–

Length-price relationship: in $ and feet

•

Find conversion factors (may need to look up)(Given on test)–

1 in = 2.54 cm (exactly)

–

1 ft = 12 in (exactly)–

1 ft = $0.15(exactly)

•

Set up problem to cancel units•

Perform math –

check value and units

60.1$ft115.0$

in12ft1

cm54.2in1cm325 =×××

More•

How many sodium atoms would it take to form a line 1 foot long (1 foot = 0.3048 m) if the diameter of a sodium atom is about 186 picometers?

•

The symbol for sodium is Na.–

Target: # Na atoms Given:1 foot

–

Conversion factors:

1 foot = 0.3048 m1 pm = 1 ×

10-12

m

1 Na atom = 186 pm–

Calculation:

912

0.3048 1 11 1.64 101 1 10 186

m pm Na atomft Na atomsft m pm−× × × = ×

×

Density –

mass and volume•

Density:

ratio of mass to volume

•

Units: g/mL, g cm3, g/L, …•

Densities of common substances:

vmdor

volumemassdensity ==

Substance Physical State Density (g/cm3)Hydrogen Gas 0.0000899Oxygen Gas 0.00133

Grain alcohol Liquid 0. 789Water Liquid 0.998

Table salt Solid 2.16Aluminum Solid 2.70

Lead Solid 11.3Gold Solid 19.3

*At room temperature(200C) and normal atmospheric pressure(1atm).

Freezing and boiling points of water

MOST COMMON CONVERSIONS IN CHEMISTRY

g A ↔ mol A ↔ mol B ↔ g B

g CO to mol CO or mol CO to g CO(periodic table converts mass ↔ to moles)1 mol CO = 28.0103 g CO

How about mol A ↔ mol B?

Mol A ↔ Mol B

•

A few ways of doing this1.Chemical formula

H2

O says that for every mole of H2

O there are two moles H or one mol O1 mol H2

O = 2 mol H = 1 mol O

How about CuSO4

•5 H2

O Conversion factors?

Mol A ↔ Mol B

•

A few ways of doing this2.Chemical reaction (balanced)

2 Al(s) + 6 H+(aq) → 2 Al3+(aq) + 3 H2

(g) 3 mol H2

= 6 mol H+

= 2 mol Al = 2 mol Al3+

USE COEFFICIENTS IN BALANCE REACTION