Today is Friday (!),September 4th, 2015

Pre-Class:You know, I really like to save money whenever I

can. This year, I’m hoping to stop paying so much for salt at the grocery store. So, the next time I’m at the beach, I’m going to take some of

the salt out of the salt water.

Is that possible? How?

In This Lesson:Mixtures

(Lesson 2 of 6)

Today’s Agenda

• Types of matter• Properties of matter• Interactions of matter– Also known as mixtures

• Where is this in my book?– P. 44 and following…

By the end of this lesson…

• You should be able to classify matter based on its composition.

• You should be able to determine the error of measurements taken during a laboratory process.

Types of Matter

• As you can imagine, having a definition as broad as “has mass, takes up space” leads to an awfully large amount of matter in the world.

• More than just the phases of matter, chemists have ways of classifying matter by its composition.

Classifying Matter

MATTER

Pure Substance Mixture

Element CompoundHomogeneous

MixtureHeterogeneous

Mixture

Substances and Mixtures

• Mixtures can be separated by physical means.– You’ll do this in a lab!

MATTER

Pure Substance MixturePhysical

Separation

MATTER

Substance Mixture

Element Compound

Substances

• Substances have:– Uniform compositions– Distinctive characteristics– Examples:• NaCl (Salt)• Al (Aluminum)• O2 (Oxygen)

MATTER

Substance Mixture

Element Compound

Elements and Compounds

• Elements are substances that cannot be broken down into components.

• Elements are composed of only one type of atom.– Example:

• Hydrogen• Oxygen• Uranium

MATTER

Substance Mixture

Element Compound

Elements and Compounds

• Compounds are composed of two or more elements.

• Compounds can be broken down chemically.– Example:• Glucose (C6H12O6)

• Water (H2O)

• Carbon Dioxide (CO2)

Chemical Separation

Mixtures

MATTER

Substance Mixture

Homo-geneousMixture

Hetero-geneousMixture

• Mixtures are physical blends of two or more substances.– Examples:• Salt water• Sand and water• Blood• Air• Vegetable soup

Substances and Mixtures

MATTER

Substance Mixture

Homo-geneousMixture

Hetero-geneousMixture

• Homogeneous mixtures are also called solutions.

• They have a “single state” – in other words, it all looks the same.– Examples:• Salt water• Crystal Light• Apple juice

Substances and Mixtures

MATTER

Substance Mixture

Homo-geneousMixture

Hetero-geneousMixture

• Heterogeneous mixtures are not uniform.

• They have more than one state – in other words, it doesn’t all look the same.– Examples:• Cookies and cream ice cream• Fruit salad• Vegetable soup

Closure

• It’s time for the “Mixture or Substance” game!– [cue 70’s game show music]

• I’ll show you a picture of a substance or mixture, you tell me which one it is.– Imaginary bonus points if you can identify

whether it’s an element or compound, or a heterogeneous or homogeneous mixture.• That sentence had many uses of the word “or.”

Salt Salt Water Air Soil Blood

Classification of MatterIs it a mixture or a substance?

Substance Mixture Mixture Mixture Mixture

Compound Homogeneous Homogeneous Heterogeneous Homogeneous

Sand Water Gasoline Iron Steel

Classification of Matter

Mixture Substance Mixture Substance Mixture

Is it a mixture or a substance?

Heterogeneous Compound Homogeneous Element Homogeneous[Alloy]

Aluminum Sand & Salt Sand & Water Raisin Bread

Brass (copper & zinc)

Classification of Matter

Substance Mixture Mixture Mixture Mixture

Is it a mixture or a substance?

Element Heterogeneous Heterogeneous Heterogeneous Homogeneous[Alloy]

Wood Carbon Dioxide Cement Candle Wax Sugar

Classification of Matter

Substance Mixture Mixture Substance

Is it a mixture or a substance?Mixture

Heterogeneous Compound Homogeneous Homogeneous Compound

Physical and Chemical Properties

• In addition to physical and chemical reactions, like we learned about previously, there are also physical and chemical properties.– They work mostly the same way.

Physical and Chemical Properties

• Physical properties are those that can be observed without actually causing a chemical reaction.

• Examples:– Density– Hardness– Melting/boiling points– Color– Smell

Important Physical Propertiesof the States of Matter

http://www.suntrek.org/images/states.gif

Important Physical Propertiesof the States of Matter

• Solids:– Definite shape/definite volume– Not easily compressed

• Liquids:– Indefinite shape/definite volume– Not easily compressed

• Gases:– Indefinite shape/indefinite volume– Easily compressed

Physical and Chemical Properties

• Chemical properties are those that cannot be observed without actually causing a chemical reaction.

• Examples:– Flammability– Corrosion (or rust-ability)

Intensive and Extensive Properties

• There are also properties considered intensive and extensive.

• Intensive properties are those that apply to any amount of a substance.

• Examples:– Color– Melting/boiling point– Combustibility

Intensive and Extensive Properties

• Extensive properties are those that vary based on the amount of a substance.

• Examples:– Volume– Length– Mass– Weight

Closure Part Deux

• Now let’s separate a mixture ourselves.– Separation of a Mixture Lab

• There’s just one more thing you need…

Percent Error

• Today will be our first lab with a considerable amount of calculations.

• Because we will all have slightly different numbers, it’s important for us (and for chemists) to be able to measure the accuracy of the measurements we’ve taken.

Accuracy

• When measuring anything, there is usually some error on the part of the scientist or the equipment.– The value calculated in the experiment is thus called the

experimental value.• There is, of course, the “true” value; the one we

would expect to get if everything went perfectly.• This is called the accepted value because scientists

have agreed that it is correct.– Accepted value is sometimes called theoretical value,

ideal value, or expected value.

Percent Error

• Therefore, to find how far off we are from what we should have gotten, we need to calculate a statistic called percent error.

• Here’s the formula – be careful of order of operations:

100)Value Accepted

|Value Accepted - alExperiment|( Error Percent

Percent Error Example

• You calculate the mass of an object to be 57.3 grams. However, your teacher tells you the object is actually 59 grams. What is your percent error?

100)59

|59 - 57.3|( Error Percent

%.882 Error Percent

100)Value Accepted

|Value Accepted - alExperiment|( Error Percent

Closure

• You collect 23 mL of liquid in a graduated cylinder. Unfortunately, the reaction you did was only supposed to make 21.4 mL. What is your percent error?

100)21.4

|21.4 - 23|( Error Percent

%.487 Error Percent

100)Value Accepted

|Value Accepted - alExperiment|( Error Percent