Ch 2 data analysis

Chapter 2: Data Analysis Section 1: Units of measurement

Intro problems: D = m V ,[object Object],[object Object]

Not so long ago……. ,[object Object],[object Object],[object Object],[object Object]

Needless to say, this led to much confusion! ,[object Object],[object Object],[object Object]

SI Units ,[object Object],[object Object]

SI Base Units Quantity Base unit Time second (s) Length meter (m) Mass kilogram (kg) Temperature kelvin (K) Amount of substance mole (mol) Electric current ampere (A) Luminous intensity candela (cd)

Time ,[object Object],[object Object],

Length ,[object Object],[object Object],[object Object],[object Object],

Mass ,[object Object],[object Object],[object Object],[object Object]

Temperature ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],Temperature

Derived Units ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Derived Units Density equals mass divided by volume.

Example: If a sample of aluminum has a mass of 13.5g and a volume of 5.0 cm 3 , what is its density? Density = mass volume D = 13.5 g 5.0 cm 3 D = 2.7 g/cm 3

Suppose a sample of aluminum is placed in a 25 ml graduated cylinder containing 10.5 ml of water. A piece of aluminum is placed in the cylinder and the level of the water rises to 13.5 ml. The density of aluminum is 2.7 g/cm 3 . What is the mass of the aluminum sample?

Practice Problems—pg. 29 # 1, 2, 3

Other Derived Quantities ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Metric Prefixes ,[object Object],[object Object],[object Object],[object Object],[object Object]

Converting Between Units ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Section 2.2 Scientific Notation and Dimensional Analysis

Scientific Notation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Change the following data into scientific notation. a. The diameter of the sun is 1 392 000 km. b. The density of the sun’s lower atmosphere is 0.000 000 028 g/cm 3 .

Practice probs. Pg. 32 #12, 13

To add or subtract in scientific notation: ,[object Object],[object Object],Ex: To add the numbers 2.70 x 10 7 15.5 x 10 6 0.165 x 10 8 Move the decimal to right (make # bigger): subtract from exponent (exp smaller) Move the decimal to left (smaller #): add to exponent (bigger exp)

To multiply or divide numbers in scientific notation: ,[object Object],[object Object],2 x 3 = 6 3 + 2 = 5 Answer = 6 x 10 5

[object Object],[object Object],To multiply or divide numbers in scientific notation: 9  3 = 3 8 – (-4) = 12 Answer = 3 x 10 12

Dimensional analysis ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Dimensional analysis cont…. 48 km x 1km = 48,000 m 1000m Conversion factor 1km = 1000 m

Practice: Convert 360 L to ml and to teaspoons:

[object Object],[object Object]

You can convert more than one unit at a time: What is a speed of 550 meters per second in kilometers per minute? HINTs: Convert one unit at a time! Units MUST be ACROSS from each other to cancel out!

Section 2.3 How reliable are measurements:

Sometimes an estimate is acceptable and sometimes it is not. ,[object Object],[object Object],[object Object],Okay? X

When scientists make measurements, they evaluate the accuracy and precision of the measurements. ,[object Object],Not accurate Accurate

[object Object],Not precise Precise

Density Data collected by 3 different students Which student is the most accurate? Which is most precise? What could cause the differences in data? Accepted density of Sucrose = 1.59 g/cm 3 Student A Student B Student C Trial 1 1.54 g/cm 3 1.40 g/cm 3 1.70 g/cm 3 Trial 2 1.60 g/cm 3 1.68 g/cm 3 1.69 g/cm 3 Trial 3 1.57 g/cm 3 1.45 g/cm 3 1.71 g/cm 3 Average 1.57 g/cm 3 1.51 g/cm 3 1.70 g/cm 3

It is important to calculate the difference between an accepted value and an experimental value. ,[object Object],[object Object],Percent error = error accepted value x 100

Calculate the percent error for Student A Percent error = error x 100 accepted value First, you must calculate the error!! Error = (experimental – accepted) Trial Density (g/cm 3 ) Accepted value Error (g/cm 3 ) 1 1.54 1.59 2 1.60 1.59 3 1.57 1.59

Significant Figures ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Significant Figures

Learning Check ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Solution

Measurement and Significant Figures ,[object Object],[object Object],[object Object],[object Object],[object Object],Chapter Two

What is the Length? ,[object Object],[object Object],[object Object],[object Object],[object Object]

Learning Check What is the length of the wooden stick? 1) 4.5 cm 2) 4.54 cm 3) 4.547 cm

Measured Numbers ,[object Object],[object Object],[object Object]

Rules for significant figures ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Trailing zeros Leading zeros 100 g has__

Determine the number of significant figures in the following masses: a. 0.000 402 30 g b. 405 000 kg a. 0.000 402 30 g b. 405 000 kg 5 sig figs 3 sig figs

To check, write the number in scientific notation ,[object Object],4.0230 x 10 -4 and has 5 significant figures

Practice probs. Pg. 39 # 31, 32

Rounding to a specific # of sig figs ,[object Object],[object Object],1. Count to four from left to right: 1 2 3 4 2. Look at the number to the right of the 4 th digit and apply rounding rules 32.54

Calculations and Sig Figs ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Calculations and Sig Figs ,[object Object],[object Object]

Practice probs. Pg. 41 # 35, 36 pg. 42 #37, 38

Ch 2 data analysis

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