Chemistry Unit 1: The Science of Matter E-Cubed Academy

Learning Objective Understand composition and their impact on the properties of matter Be able to classify chemical vs. physical changes

A Science for All Seasons What is Chemistry? –The study of the composition of matter –The study of the changes matter undergoes Why study Chemistry? –Chemistry touches all aspects of life –A basic understanding of chemistry will enable you to make informed and balanced decisions

In your Notes List at least 5 chemicals that you are familiar with from past experience.

Chemistry The science that investigates the structure and properties of matter Matter: anything that takes up space and has mass Mass: the measure of the amount of matter that an object contains NOT Matter- HeatLight Radio waves etc.

Matter continued Structure: refers to what it is made of and of how it is organized Properties: Describe the characteristics and behavior of matter including the changes it undergoes

Behavior of Matter Determined by BOTH The elements it contains Arrangement of those elements

Example Salt vs. Water Salt vs. Water Sodium and Chloride Hydrogen and Oxygen Contain different elements --- Have different properties!

Example AspirinVs Table Sugar Both contain only Carbon, Hydrogen and Oxygen molecules --- same composition Different Structures Cause Different Behaviors!

Chemistry: Physical Properties Properties that can be observed without changing the substance Easily observed or measured Using five senses BP, MP, color, physical room temperature, odor, electrical conductivity, solubility, magnetism, density, taste, crystal form

Chemistry: Chemical Properties Those properties of a substance that can only be studied by forming new substances, through a change in composition called a chemical reaction Describes how something reacts with another substance how a substance behaves in the presence of another substance Flammability, reactivity with acid, pH, heat of combustion

Physical change vs. Chemical change Physical ChangeChemical Change Doesn't change what the substance is. A new substance is formed and energy is either given off or absorbed. Can be reversedCannot be reversed with the substance changed back without extraordinary means, if at all.

Examples Physical Change Chemical Change Paper cut into pieces, small pieces are still paper Paper burned is no longer paper Dissolve sugar in waterMake a cake with flour, water, sugar and other ingredients and bake them, it would take extraordinary means to separate the various ingredients out to their original form.

Let’s look closely at Density It is an important property of matter It is used to identify substances It is also used to separate mixtures Definition of Density: the mass of a specific unit of volume It is expressed in the following equation; D= m/v or density = mass volume volume

Example of Density Calculations If a piece of rock has a mass of 14g and a volume of 5 cm 3, what is the density? Step 1: Write the given and ensure proper units m =14 g V= 5 cm 3 Step 2: Write the formula D= m/v Step 3: Substitute the given into the formula D = 14g / 5 cm 3 Step 4: solve D=2.8 g/cm 3

Density of Penny 1982 when the switch happened After 1982= more shiny Less dense after 1982

Density Density is a physical property Characteristic for a substance Can be used to identify a substance How “thick” something is... D = mass / volume Units of g/cm 3 for solids and g/mL for liquids Something less dense will float on something more dense

Unit Conversions Write conversion factors for the following: 1000 cm 3 = 1000 mL 1 kg = 1000 g 1 kg = 2.2 lb 1 L = 1000 mL How many kg are in 76 g? How many grams are in 0.53 kg? How many mL are in L?

Answers 1).076 kg 2) 530g 3) 439 mL

worksheet Work in groups and complete the problems

Classifying Matter 1.Substance: matter with constant composition a)Element: Made of only one type of atom b)Compound: 2 or more elements that are chemically combined 2.Mixture: Matter with variable composition a)Heterogeneous Mixture: Made up of more than 1 phase b)Homogeneous Mixture: also called solutions, made up of only 1 phase

Mixtures A material that is made of 2 or more things which are not combined chemically Each of the parts still keep their own identities Made by blending, but NOT forming chemical bonds or chemical change! Most everyday matter occurs as mixtures

Heterogeneous and Homogeneous Mixtures A classification of matter based on composition Homogeneous mixture: no clumping or grouping but rather a uniform dispersal of the material it is made of. Ex. Air; made of N2, O2, CO2 and other gases A liquid in which there is a solvent and a solute is called a solution Heterogeneous mixture: it is easy to identify all if the different components

Matter: Homogeneous and Heterogeneous Mixtures

Homogeneous Mixtures

REMEMBER Mixtures Are made of 2 or more things which are not combined chemically Each of the parts still keep their own identities Made by blending, but NOT forming chemical bonds or chemical change! Most everyday matter occurs as mixtures

Separating Mixtures Mixtures can be separated through a physical process, (the identity of the substance remains unchanged). Using their Physical properties Bringing about physical changes to separate the mixture into its components (different substances it is made of)

Making a Mixture AND SANDSUGAR

The Mixture

How can we separate it? What do you think? Work with your lab partner to come up with a suggested method. (10 minutes) You may use your class notes, but your brain is your best asset. Write your thoughts in your notebooks. Do not be afraid to try!

Report out on ideas So, what did you come up with? Share your thoughts! (10 minutes)

What can we do? Method #1 Use a pair of tweezers and a microscope to physically separate the particles Requires a lot of time and patience

Method #2 Step #1 Recall the properties of water and of sand Recall the properties of water and of sand Sugar dissolves in water Sand does NOT Use the difference! Use the difference!

Step #2 Recall the properties again Recall the properties again sand will not pass through a filter Sugar and water solution will Use the difference! Use the difference!

Step #3 Recall the properties of sugar and water Recall the properties of sugar and water sugar will not evaporate (change state) at 100 degrees Celsius water will ! Use the difference! Use the difference! Step #4

You have the two pure substances again! Sand in the filter! Sugar in the bottom of the beaker!

Lab Tomorrow Separating Mixtures

REMEMBER: Physical Properties 1. Density: Mass per unit volume 2.Solubility in water : Does it dissolve in water? 3.State of mater: at room temp and pressure 4.Transparency: lets light pass through 5. Boiling point: Temperature at which a substance goes from liquid to gas 6.Melting point: Temperature at which a substance goes from solid to a liquid 7. Brittleness: Tendency to crack or break 8. Ductility: Ability to bend without breaking 9.Elasticity: Ability to be stretched or compressed then return to original size

Chemical properties Chemical Property Flammability: The ability to burn Flammability: The ability to burn Ability to rust: Reacts with oxygen to produce rust Ability to rust: Reacts with oxygen to produce rust Reactivity with vinegar: Reacts with vinegar to produce new substances Reactivity with vinegar: Reacts with vinegar to produce new substances

Solutions (homogeneous) Air (gas) Martini (liquid) Salt water (liquid) Plastic (solid)

Substances Homogeneous materials that contain only 1 kind of matter Have definite composition and properties Substances which can not be broken down into a simpler substance is an ELEMENT. Substances which can be broken down into a simpler substance is a COMPOUND. They are made of 2 or more elements

Elements Made of only one kind of atom Can not be made simplified by physical or chemical means Can exist as atoms (carbon) or molecules (N2)

Compounds Consist of 2 or more DIFFERENT atoms bound together (H2O) Can be broken down into smaller types of matter by chemical means only. Have properties which are different than the elements they are made of Always contain the same ratio of its components atoms ( ex 2 hydrogen's to 1 oxygen, in water)

Elements, Compounds, Mixtures Sodium is an element. Chlorine is an element. When sodium and chlorine bond they make the compound sodium chloride, commonly known as table salt.  Compounds have different properties than the elements that make them up.  Table salt has different properties than sodium, an explosive metal, and chlorine, a poisonous gas.

Classify the Following 1.Ocean water- 2.Calcium- 3.Vitamin C- 4.Dry ice – 5.Copper- 6.Grain alcohol- 7.after shave lotion- 8.Hamburger- 9.Al foil – 10.Milk- 11.Salt- 12.Iron nail-

Answers 1.Ocean water- solution 2.Calcium- element 3.Vitamin C- Compound ( L-asorbic acid) 4.Dry ice – compound (CO2) 5.Copper- element 6.Grain alcohol- compound (C2H5OH) 7.after shave lotion- heterogenous mixture 8.Hamburger- hetero 9.Al foil – element 10.Milk- solution 11.Salt- cmpd 12.Iron nail- element

Mixtures vs. Pure substances Mixtures can be separated based physical properties and through physical change Pure substances can only be separated through chemical changes Separated from compounds into elements H2O-  H and O2 Made into compounds from elements H + O  H2O

Chemical Change and Energy All chemical changes involve some sort of energy change! Many chemical changes (reactions) release energy Exothermic reactions: release energy as heat Some reactions absorb energy Endothermic reactions: absorb heat energy

Demo Epsom salt and laundry detergent