Chapter1_2013T2 for Students

Chemistry 112.3

2013-2014 Term 2

Alexandra Bartole-Scott

Office Number : Thorv G51.3

Email : [email protected]

Chapter 1 : Matter, Measurement and

Problem Solving Outline

1) The Scientific Approach

2) The Classification of Matter

3) Properties and Changes of Matter

4) Energy

5) Units and the S.I. system

6) Reliability of a measurement

7) Solving Chemical Problems

Read these sections

On your own,

Bring any questions

To next class

You are responsible for all of Chapter 1 material.

Classifying Matter

Classifications in matter

How to further classify matter ? Not in book

More about matter

An Example of a Physical Change…

changes that

alter the state or

appearance of

the matter

without altering

the composition

are called

physical changes

Page 10

An Example of a Chemical Change…

changes that alter the

composition of the matter are

called chemical changes

during the chemical change,

the atoms that are present

rearrange into new molecules,

but all of the original atoms are

still present

More about matter

C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l)

Page 11

Units of Measurement

SI : Système Internationale

Quantity Unit Symbol

Length Meter m

Mass Kilogram kg

Time Second s

Temperature Kelvin K

Amount of

substance

Mole mol

Units

Page 16

Prefix Symbol Decimal

Equivalent Power of 10

mega- M 1,000,000 Base x 106

kilo- k 1,000 Base x 103

deci- d 0.1 Base x 10-1

centi- c 0.01 Base x 10-2

milli- m 0.001 Base x 10-3

micro- m or mc 0.000 001 Base x 10-6

nano- n 0.000 000 001 Base x 10-9

pico p 0.000 000 000 001 Base x 10-12

Nanotechnology – refers to length scales

1,000,000,000 times smaller than a meter !

Units

Page 19

Derived Units

meters

seconds

lengthvelocity

time

3 x x metersvolume length length length

3

g

m

massdensity

volume

Definition : Combinations of the base quantities of length,

mass, time, temperature, etc…

Examples :

% 100% [%]

mass of componentcomposition x

total mass

Units

Page 18-20

Working in Groups:

Groups of 4

- Manager – reads the questions, keeps track of time,

represents group in the classroom

- Recorder - Writes down the group’s answers/work

- Fact-checker – looks up important data, equations, etc.

- Presenter – does calculations, presents the group’s

answers…

Task #1: Find a group of 4, move around if you need to

Task #2: Decide roles in group (will give you 5 minutes to get

settled)

Roles should change each lecture day that we incorporate

group work…

Task #3: Attempt next question

Example 1.2 Calculating Density

Units

Page 22

A man receives a ring from his fiancée. The ring has a mass

of 3.15 g, and displaces 0.233 cm3 of water.

Is the ring made of Platinum?

The Reliability of a Measurement Example 1.3 Reporting the Correct

Number of Digits

What is the volume in this graduate cylinder?

All measurements are susceptible to error.

Reliability of a measurement

Page 26

Reliability of a measurement

Significant Figures Page 27

Why are Significant Figures Important?

They tell others how confident you are in a number…your

ability to communicate and analyze numerical results is

critical whether you’re headed for a career as an

engineer, scientist, doctor…etc.

For example, fish containing 1.5 ppm (part per million)

mercury are not deemed fit for human consumption. A

sample of tuna is sent to three different labs for analysis.

Labs Lab A Lab B Lab C

Measured

values

1.2 ppm 1 ppm 1.17523 ppm

Which lab result are you most confident in?

Would you feel safe in consuming this sample of fish?

when multiplying or dividing measurements with

significant figures, the result has the same number

of significant figures as the measurement with the

fewest number of significant figures

Examples: How many sig figs in the answer???

5.02 × 89,665 × 0.10 = 45.0118

.

5.892 ÷ 6.10 = 0.96590

Carrying Significant Figures in Calculations

Reliability of a measurement

Pages 30-32

when adding or subtracting measurements with

significant figures, the result has the same number

of decimal places as the measurement with the

fewest number of decimal places (example: Money:

$12.46 + $1.54 = $14.00 not $14.0000 or $14.)

5.74 + 0.823 + 2.651 = 9.214

4.8 - 3.965 = 0.835

Reliability of a measurement

Pages 30-32

Most students forget about the addition-subtraction rule!!

Perform each calculation to the correct # of significant figures

You can calculate these on your own…but how many sig

figs??

(a) 1.10 x 0.5120 x 4.0015 ÷ 3.455

(b) 0.355 + 105.1 – 100.5820

(c) 4.562 x 3.99870 ÷ (452.6755 – 452.33)

(d) (14.84 x 0.55) – 8.02

For more practice – Significant Figures Practice sheet on p.

xxxiii of Lab Manual (due on First lab)

Reliability of a measurement

Example 1.5 Significant Figures

In Calculations

Page 32

3 sig figs

1 decimal place

2 decimal places in

bracket leads to 2 sig figs

1 decimal place

Error Type Definition

Systematic Inherent error. For example, poor

instrument calibration.

Random Limitations in the skill of experimenter

ability to read a scientific instrument.

Accuracy - How close your experimental measurement is

to the correct answer.

Precision - Refers to the degree of reproducibility of a

measured quantity.

Reliability of a measurement

Error

Can be identified and eliminated !

Page 33

Accuracy vs Precision –Example 1

Accuracy vs Precision –Example 2

Accuracy vs Precision –Example 3

Converting Units

Converting Units Pages 34-35

Volume

MassDensity

Density

Mass Volume

Volume Density Mass

m, V D

m, D V

V, D m

A 747 is fueled with 173,231 L of jet fuel. If the density of the

fuel is 0.768 g/cm3, what is the mass of the fuel in kg?

Work in groups

Reminder: Roles – Manager

Recorder

Fact-checker

Presenter

Conversions

Example 1.6 Density as a

Conversion Factor

Page 37

Challenge problem-Groups Not in book

The density of copper is 8.92 g/cm3 If a 10.00 g sample of copper is

Placed into a graduated cylinder that contains 15.0 mL of water,

What is the total volume of the mixture?? ie. How high does the

Water get in the grad cylinder?

a) 15.0 mL

b) 25.0 mL

c) 16.1 mL

d) 1.12 mL

e) 23.9 mL

Example 1.7 – p40

Find the radius r, in cm of a spherical droplet of water with a

volume of (V) of 0.058 cm3 .

For a sphere, V = 4/3 r3

Your job for next class…

Get a workbook and lab manual if you don’t already have them

Get supplies (safety glasses, calculator etc),

complete the Significant Figures Practice Sheet on page xxxiii

Register for masteringchemistry.com using access kit

Read through Chapters 1 and 2 of workbook since we will be doing

Problems from Chap 2 next class!