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# Ch 1

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## Angela Mcguirk

on 5 January 2017

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#### Transcript of Ch 1

What else do we need to know?

We also need to know the “true” value to determine accuracy.

Let’s assume the actual value for this object was 7.4413g.

Are we Accurate?

Chapter 1
Chemistry: Matter and Measurement

35

LDL is the bad cholesterol because it keeps blood
cholesterol circulating in your bloodstream, leaving plaque on artery walls along the way.

HDL is the good cholesterol because it acts like waste removal carriers moving cholesterol from blood and arteries to your liver for removal from your blood.

Cholesterol and Density

26

No! We often interchange the two terms creating a language problem.

For example, when a person goes to the moon.

Mass does NOT change, but the person becomes almost weightless!

When on Earth the two terms are often interchanged.

Are Mass and Weight the same thing?

22

Base Units

19

Number in Number in
Object Standard Format Scientific Notation
Avogadro’s number 602,000,000,000,000,000,000,000 molecules 6.02 x 1023 molecules

Mass of a human 68 kg 6.8 E 1 kg

Length of a pox virus 0.000 03cm 3 E -5cm

Standard Format and Scientific Notation examples

7

5

Mendeleev’s Table

Dimensional analysis: A method that uses a conversion factor to convert a quantity expressed in one unit to an equivalent quantity in a different unit

Conversion factor: Expresses the relationship between two different units

Calculations: Converting from One Unit to Another

65

If we compare the actual value to our average value they are the same meaning we have very good accuracy as well.

Average = (7.4413 g + 7.4413 g + 7.4414 g)/3 = 7.4413 g

We must calculate the average (or mean) of the three trials.

Average = Sum of trials / Number of trials

To determine Accuracy

All three trial values are within +- 0.0001 g of each
other meaning there is very good precision for these measurements.

Suppose you weigh an object three times and record
the information in the following table.

Volume and Its Measurement

33

Meter
1790: One ten-millionth of the distance from the equator to the
North pole along a meridian running through Paris, France

1889: Distance between two thin lines on a bar of platinum-iridium
alloy stored near Paris, France

1983: The distance light travels in a vacuum in 1/299,792,458 of a second

Length and Its Measurement

27

18

Numbers written in scientific notation have three parts:
coefficient power of 10 unit

Scientific Notation and Calculators

Number to enter: 4 x 10^6
Enter: 4 EXP (EE or 10^x) 6
Display: 4 06 or 4 x 10^6 or 4 E06

Number to enter: 2.5 x 10−4
Enter: 2.5 EXP (EE or 10^x) +/− 4
Display: 2.5 −04 or 2.5x 10^04 or 2.5 E−04

Scientific Notation

Chapter 1/*

Know Element Name/Symbol for the empty boxes

http://www.chemistry.co.nz/mendeleev.htm

4

Dmitri Mendeleev (1869)

The Various Parts of the Scientific Method

Zeros in the middle of a number are like any other digit; they are always significant.

Rules for counting significant figures (left-to-right):

4.803 cm 4 SF

Accuracy, Precision, and Significant Figures in Measurement

43

Heat and its Measurement

Derived Units

31

Mass and Its Measurement

25

Some Chemical Properties of the Elements

13

Some Chemical Properties of the Elements

11

Properties of the Elements

8

6

Mendeleev’s Predictions

Chemistry and the Elements

3

If the first digit you remove is less than 5, round down by
dropping it and all following numbers.

If the first digit you remove is 6 or greater, round up by adding 1 to the digit on the left.

If the first digit you remove is 5 and there are more nonzero digits following, round up.

Rules for rounding off numbers:

5.664 525 = 5.665

Rounding Numbers

61

If the first digit you remove is less than 5, round down by dropping it and all following numbers.

Rules for rounding off numbers:

5.664 525 = 5.66

Rounding Numbers

59

Rules for counting significant figures (left-to-right):

34,200 m ? SF

Zeros at the end of a number and before the decimal point may or may not be significant.

Accuracy, Precision, and Significant Figures in Measurement

56

Zeros at the beginning of a number are not significant (placeholders).

Rules for counting significant figures (left-to-right):

0.006 61 g 3 SF (or 6.61 E-3 g)

Accuracy, Precision, and Significant Figures in Measurement

54

Mass of a Tennis Ball
(True Mass = 54.441 778 g)

poor accuracy
poor precision

Accuracy, Precision, and Significant Figures in Measurement

All other units are derived from these fundamental units.

Système Internationale d´Unités

Experimentation and Measurement

17

Semimetals (metalloids): Tend to lie along the zigzag line in the periodic table

Some Chemical Properties of the Elements

16

Nonmetals: Right side of the zigzag line in the periodic table

Some Chemical Properties of the Elements

15

Metals: Left side of the zigzag line in the periodic table (except for hydrogen)

Some Chemical Properties of the Elements

Some Chemical Properties of the Elements

12

Some Chemical Properties of the Elements

10

5.664 525 = 5.664 52

If the first digit you remove is less than 5, round down
by dropping it and all following numbers.

If the first digit you remove is 6 or greater, round up by adding 1 to the digit on the left.

If the first digit you remove is 5 and there are more nonzero digits following, round up.

If the digit you remove is a 5 with nothing following, round down.

Rules for rounding off numbers:

Rounding Numbers

62

If the first digit you remove is 6 or greater, round up by adding 1 to the digit on the left.

Rules for rounding off numbers:

5.664 525 = 5.7

Rounding Numbers

60

Zeros at the end of a number and after the decimal point are always significant.

Rules for counting significant figures (left-to-right):

55.220 K 5 SF

Accuracy, Precision, and Significant Figures in Measurement

55

Mass of a Tennis Ball
(True Mass = 54.441 778 g)

good accuracy
poor precision

Accuracy, Precision, and Significant Figures in Measurement

51

good accuracy
good precision

Accuracy, Precision, and Significant Figures in Measurement

Mass of a Tennis Ball
(True Mass = 54.441 778 g)

Density and Its Measurement

34

Math rules for keeping track of significant figures:

2 decimal places

3.19 315

2 decimal places

5 decimal places

3.18

+ 0.01 315

3.19

Addition or subtraction: The answer can’t have more digits to the right
of the decimal point than any of the original numbers.

Rounding Numbers

58

converts
in to m

converts
m to in

1 m

39.37 in

or

39.37 in

1 m

Relationship:

Conversion factor:

1 m = 39.37 in

Calculations: Converting from One Unit to Another

66

Multiplication or division: The answer can’t have more significant figures
than any of the original numbers.

Math rules for keeping track of significant figures:

= 23.760 684 mi/gal

3 SF

3 SF

4 SF

= 23.8 mi/gal

278 mi

11.70 gal

Rounding Numbers

57

K = oC + 273.15

oF =

5 oC

9 oF

oC + 32 oF

oC =

9 oF

5 oC

(oF - 32 oF)

Temperature and Its Measurement

29

Conversion Factor

Given Unit

Needed Unit

x

= 1.77 m

69.5 in

1 m

39.37 in

Calculations: Converting from One Unit to Another

67

Know!
Energy - The ability to do work or supply heat
Units: Joule, calorie, Calorie
Types: Kinetic and Potential
Kinetic energy - energy of motion

E_k_ = (1/2) mv^2
Potential energy- stored energy

E_p_ = mgh
Joule (J) - relatively small unit; often use kJ in our measurements
calorie - amount of energy necessary to raise the temperature of 1g of water by 1 degree Celsius
Calorie - Nutritional Food Calorie
1000 J = 1kJ

1 cal = 4.184 J

1 Cal = 1000 cal = 1 kcal
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