Unit 1 – Science, Measurement, and Methods

Conceptual Chemistry

Unit Objectives

1. Use examples to explain the various branches of science.

2. Distinguish between qualitative and quantitative observations.

3. List the SI units of measurement and common prefixes.

4. Convert units using dimensional analysis.

5. Diagram and explain the various components of experimental design.

6. Calculate the density of an object from experimental data.

Objectives 1 & 2

1.) Use examples to explain the various branches of science.

2.) Distinguish between qualitative and quantitative observations.

Uses of Science

1.) Analytical2.) Classification3.) Invention4.) Scientific Method

1.) Analytical

Involves laboratory analysis to find out what something is made of.

Example: forensics1. Quantitative – numerical amounts

measuredExample: 1.9 cm, 2.00 g,

55.3oC2. Qualitative – measured with senses

Example: short, heavy, hot

2.) Classification

Gives us a common language.Example: Chemistry- elements on the periodic table

Biology- plants vs. animals

3.) Invention

Creating or producing by using your imagination.

There are no rules!Example: mobius strips

4.) Scientific Method

Method of research in which a problem is identified, data is gathered, a hypothesis is formed from this data, and the hypothesis is tested.

Used to prove or disprove something.

There are strict rules!

Branches of Science

1.Biological2.Physical3.Earth

1.) Biological Science

The study of living things. (bio = life) Video Example 1

Video Example 2

2.) Physical Science

The study of non-living materials and or energy. Video Example 1

Video Example 2

3.) Earth Science

The study of non-living earth features. Video Example 1

Video Example 2

Try These!

Link 1

Link 2

Objective 5

Diagram and explain the various components of experimental design.

Scientific Method

Used for formal research. Observation/Stating a Question or

Problem Gathering Information Forming a Hypothesis Experimental Design Recording and Analyzing data State a Conclusion Repeat

Observation/Stating a Question or Problem

Varies depending on the project.Looking to prove or disprove a

point.

Gathering Information

Research what is already known.Use and keep track of credible

sources.

Forming a Hypothesis

If…then…because…

Experimental Design

Change only 1 variable. Controls: Normal, unchanged part Experimental Group: Changed

part▪ Independent Variable: “I” change the “I”ndependent variable.▪Dependent Variable: Outcome you hope depends on your change.

Recording and Analyzing Data

Data TablesGraphsCalculations

State a Conclusion

Based on experimental results.Use gathered information to

support original question or problem.

Repeat

Multiple trials lead to more reliable results.

Helicopter Activity1.) Draw a picture of the control group and experimental group. 2.) Label the independent variable.3.) Describe the dependent.

Control Group Experimental Group

Objective 3

List the SI units of measurement and common prefixes.

Reading between the lines with graduated cylinders and rulers.

Metric Ruler Metric Ruler

Practice (rulers)

Measure and diagram the sheet of paper in your Lab Notebook.

Reading between the lines with graduated cylinders and rulers.

Graduated Cylinder

Practice (graduated cylinders)

Graduated Cylinder Graduated Cylinder

Measurement

Science uses the metric system. Basic Units Also called Standard International or

S.I. Units

S.I. Unitshttp://www.youtube.com/watch?v=pikrntjcbyw

Quantity Units Symbol

Example

Length meters m average human ~ 1.6 m

Mass kilograms kg 1 penny ~ 1 g

Volume Liters L 2 L bottle

Density mass/volume

g/mL or

g/cm3

density of water ~ 1 g/mL

Temperature

kelvin K room temperature = 293 K

Time seconds s 1 min = 60 sec

Pressure Pascals Pa 101,000 Pa = sea level

Temperature

Basic Unit is kelvin.It is found by oC + 273 = kelvin

Degrees Celsius to Kelvin

oC + 273 = kelvin 0oC is actually 273 Kelvin. Still lots of

energy.o 0oC + 273 = 273 K

100oC is equal to 373 Ko 100oC + 273 = 373 K

-273oC is equal to 0 Ko -273oC + 273 = 0Ko This is called absolute zero. Everything

stops at this temperature.

Practice Problems

1. Antarctica can get as cold as -100oC. How many K is this?

2. If global warming continues, Earth could earn an average temperature of 313 K. How many oC would this be?

Metric Prefixes (from large to small)

Nano-

n billionth 1/1,000,000,000 DNA

Prefix

Symbol

Meaning Multiplied size Example

tera- T trillion 1,000,000,000,000

terabytes

giga- G billion 1,000,000,000 gigabytes

mega-

M million 1,000,000 mega million

kilo- k thousand 1,000 10 kilometer race = 7.2 mi

centi- c hundredth

1/100 finger nail

milli- m thousandth

1/1,000 thickness of penny

micro-

µ millionth 1/1,000,000 human cells

Objective 6

Calculate the density of an object from experimental data.

Density Practice

Density: The ratio of the mass of an object to its volume.

Density = mass / volume The density of substances changes

with temperature.

Density of Rectangular Object(Wood Block)

Show with pictures, label all values, and show math

1)Measure dimensions of Block (cm)2)Measure mass of Block (g)3)Calculate Density of Block

Density of a Liquid (water)

Show with pictures, label all values, and show math

1)Mass of empty Graduated Cylinder2)Measure 50 mL of Water in Cylinder3)Mass of water and Cylinder together4)Calculate Mass of Water5)Calculate Density of Water

Density of an Irregular Solid(Puddy)

Show with pictures, label all values, and show math

1)Measure mass of object2)Use partially full G. Cylinder – record

volume3)Place object in G. Cylinder – record

new volume4)Calculate Volume of object5)Calculate Density of object

Example

What is the density of an object with a mass of 4.00 g and a volume of 4.00 ml?

More on Density

Density is the ratio of the mass of an object to its volume Ie: Water density = 1.0 g/ml Cork density is less than 1.0 g/ml

The formula for density is D= mass / volume

Question

If you have two objects of the same size, and object A is more dense than object B, which one will have more mass?

Rectangular Solid Example

Dice

Odd Shaped Solid Example

Wax

Liquid Example

Corn Syrup

Objective 4

Convert units using dimensional analysis.

Converting Units

You must always SHOW WORK when converting units. This will pay huge dividends for your entire science future.

Math Review

Any number can be written over one. It will not change the value. o 7/1 = 7

Any number divided by itself equals one. o 7/7 = 1

If you multiply by one, it will stay the same. So if you multiply by a conversion factor, you are really

multiplying by one. Any amount divided by the exact same amount

equals one. *This is called a conversion factor (a fraction with equal

amounts on top and bottom, but in different Units)

Dimensional Analysis(AKA: Showing your work.)

1. Write down the given number, with units.2. Choose a conversion factor that will get you away from

what you’re GIVEN, and get you to what you WANT. Remember, the TOP and BOTTOM of the fraction must be an EQUAL amount, so it really only equals ONE.

3. Place your conversion factor next to the given number so that it is MULTIPLIED using A FRACTION. Make sure what you WANT is on top, and what your getting rid of is on BOTTOM.

4. If multiple changes are needed, just multiply by multiple conversion factors.

5. Cross of units that appear on TOP and BOTTOM. The only unit left should be the one you WANT.

6. In your calculator, multiply all TOP numbers, divide by any BOTTOM numbers.

Examples, step by step.

One step problem: Convert 3 weeks to days.

Convert 62 inches to centimeters (1 inch = 2.54 cm)

Convert 75 miles to kilometers (0.62 miles = 1 km)

Examples, step by step.

Two step problem: Convert 3 weeks to hours.

Four step problem: Convert 3 weeks to seconds.

What's the method for Converting Units?

Example 2: Convert 215 miles into Kilometers.

Practice Problems

1. How many fingers would be on 12 hands?

2. How many centimeters would be in 200 meters?

3. How many kilometers is 2,043 meters?