The Study of the Universe!

When Doing Labs• Use the Scientific Method – accepted

method for scientists to explain how things work

• Steps:

1.State Problem and Collect Data2.Formulate Hypothesis3.Perform Experiments

Step 1: Collecting Data [Two Types]Quality vs. Quantity?Qualitative (Quality)

NO NUMBERS involved

Ex. The sky is blue

Ex. The solution is cloudy

Quantitative (Quantity)

NUMBERS involved

Ex. The solution is 34.50 grams

Ex. Water boils at 100 degrees

Step 2: Hypothesis• Hypothesis – a

POSSIBLE explanation for why something happens

• Observations are NOT hypotheses

• Ex. the solution is cloudy (observation)

• Ex. the solution is cloudy because it is contaminated (hypothesis)

Step 3: ExperimentsUse controls and

variables

Control – the constant

Variable – the thing that changes in the experiment

Lake vs. Ocean

Perform multiple Trials – attempts at experiment

When Measuring Liquids…Meniscus – curve at

upper surface of liquid

Measure liquids HERE

Quick Quiz #1The scientist notes that there are 42 eggs in

the basket. Is this a qualitative or quantitative measurement?

What is a variable?

When measuring volumes of liquids, what is the curved line that you use?

Types of ChemicalsFlammables and Combustibles –

chemicals that can catch on fire

Corrosives – things that damage/burn through skin tissue

Pressure – chemicals that are dangerous at different pressures

FlammablesEx. Bunsen Burners

(used in this lab!)

Precaution: WEAR GOGGLES!

Similar but NOT the same as COMBUSTABLES – catch fire at HIGH temperatures

Handling Boiling/Hot ChemicalsDON’T TOUCH

WITH BARE HANDS!

USE TONGS or “Hot Hands”

CorrosivesCorrosives = acids

and bases that can damage skin

Precautions: WEAR GLOVES, PROTECTIVE CLOTHING (long-sleeves) AND GOGGLES

If Corrosive Chemicals Get On Skin…RINSE

IMMEDIATELY

continuous running water (NOT SOAP)

Eyes – RINSE IMMEDIATELY for at least 5 minutes under eye wash.

Broken GlassAccidents happen (no,

really)

Broken glass (beakers, test tubes, thermometers, etc) LET ME KNOW ASAP!

Move away from station until glass is cleared

Warm Up #5

Converting Units

Amurrica vs. The WorldAmurrica The Rest of the World

Distance: Inches, Feet, Miles

Volume: Cups, Quarts, Gallons

Mass: Ounces, Pounds, Tons

WHY DOES THIS STILL EXIST?

Distance: Millimeters, Meters, Kilometers

Volume: Milliliters, Liters, Kilometers

Mass: Milligrams, Grams, Kilograms

THIS IS WAY EASIER.

The Metric System Prefixes

Going from BIG to smallEx: 145.8 Decimeters (dm) into Kilometers

(km)

FOUR decimal places from DECI to KILO

Move Decimal FOUR PLACES LEFT

145.8 dm = 0.01458

Quick Quiz #3Convert the following:

34.67 mL = ____ L?

4.903 hg = _____ dg?

John travelled a distance of 290480000 millimeters. How many kilometers is that?

Density and SpeedDensity: Concentration

of a substance in a given space

Mass over Volume (m/v)Ex. g/mL, kg/L, etc.

Speed: rate at which an object moves

Distance over Time (d/t)Ex. m/s, km/hr, etc.

Dimensional Analysis Intro.Problem #1: Karla has a substance with a

density of 4.68 g/mL. How many g/cL is that?

Problem #2: James was measuring the speed of a car in meters per second. If he found that a car was moving at the speed of 5.50 m/s, how many km/hr is that?

On your Calculator:500 x 500 = 250000. (that’s a

big number!)

.005 x .005 = 2.5-05 (WTF?)

Why does the second answer look like this?

Scientific NotationScientific Notation – way of

making REALLY big or REALLY small numbers easy to read.

General Form:

M x 10n

M = number between 1 and 10n = number of decimal places

you move

2 500 000 000.9 8 7 6 5 4 3 2 1

Step 1: Insert an understood decimal pointStep 2: Decide where the decimal must end up so that

one number is to the leftStep 3: Count how many places you bounce the

decimal pointStep 4: Re-write in the form M x 10n

2.5 x 109

The exponent is the number of places we moved the decimal TO THE LEFT.

Quick Quiz #1Multiply 123456 x 7890 on your calculator

1.What was your answer?2.Write your answer in scientific notation.

Do the same for the following problems:

1.98765 x 43210 = ?2.10000 x 892800 = ?3.90 x 9 = ?

0. 0 0 0 0 2 5 0. 0 0 0 0 2 5 1 2 3 4 5 1 2 3 4 5

WITH NUMBERS SMALLER WITH NUMBERS SMALLER THAN ONETHAN ONE……

2.5 x 10-5

The exponent is negative because the number we

started with was less than 1.

Review:WITH NUMBERS WAY BIGGER THAN 1

MOVE DECIMAL TO THE LEFTn VALUE WILL BE A POSITIVE NUMBER

WITH NUMBERS WAY SMALLER THAN 1

MOVE DECIMAL TO THE RIGHTn VALUE WILL BE A NEGATIVE NUMBER

Part 1

What does that mean?Dimensional Analysis– Converting one thing to another

Used in chemistry (converting units of mass/distance/volume)

BUT YOU DO THIS IN REAL LIFE ALL THE TIME

Convert the following:How many seconds in a

minute?1 minute = ___ seconds

How many quarters in a dollar?1 dollar = ___ quarters

How many points do you score in a touchdown?1 touchdown = ___

points

OR

OR

OR

1 min.

1 min.60 sec.

60 sec.

$1

$1

Example ProblemJulia measured the length of Catherine’s hair.

She found out that her hair was 24 inches long. How many feet is that?

First ask yourself:What is your starting amount?What are you converting to?How many inches are in a foot?

Reminder: UNITSDO NOT LEAVE ANY NUMBER NAKED!

IT NEEDS A UNIT.

GOAL: CANCELLING OUT UNITS

One unit label on top, the other on bottomFeet will cancel out (Feet x Feet) = Feet2

Feet

System to Do This:DIMENSIONAL ANALYSISStarting amount, draw

a line underneath it.

Draw a vertical line next to it.

One unit on top, other on bottom

Multiply stuff on topMultiply stuff on

bottomDivide Top and Bottom

Quick Quiz #2Convert the following using Dimensional

Analysis:

12 feet = ___ inches? (1 foot = 12 inches)

9 touchdowns = ___ points? (1 TD = 6 points)

4 apples = ___ oranges? (1 apple = 3 oranges)

Word ProblemsRead the problems carefully

Underline important information (things with numbers)

Know what units you start with

Know what units you need to end with

Example ProblemSteven was REALLY thirsty, so he wanted to buy some water bottles from Mr. Lockett. He ended up buying 4 water bottles. If each water bottle costs $2, how much money (in dollars) did he spend?

Underline Important Info.Steven was REALLY thirsty, so he wanted to buy some water bottles from Mr. Lockett. He ended up buying 4 water bottles. If each water bottle costs $2, how much money (in dollars) did he spend?

Solve Using Dimensional Analysis

4 Water Bottles

1 Water Bottle

2 Dollars

Starting Materials (INCLUDE UNITS)

=

Convert One Thing to Another

4 x 2

1

= 8 Dollars

Quick Quiz #3: SOLVE USING DIMENSIONAL ANALYSIS

1. Guadalupe was bored and wanted class to be over. Mr. Lockett said class was over in 90 minutes. How many hours is that? (1 hour = 60 minutes)

2. For some reason Esteban really wanted quarters. He gives the cashier a 5 dollar bill. How many quarters will he get from this 5 dollar bill? (1 dollar = 4 quarters)