Compounds Mixtures 2010

8/9/2019 Compounds Mixtures 2010

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Compounds & MixturesLesson Outline

Properties of compounds & mixtures

Differences between compounds & mixturesCompounds & mixtures around us!


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Compounds & Mixtures

At the end of the lesson, students should be able to:

describe compounds as substances consisting oftwo or

more chemically combined elements.

state different ways to make compounds.

describe mixtures as two ormore elements and/or

compounds that are not chemically combined together.

describe the differencesbetween elements, compounds

and mixtures.


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A chemical compound is a chemical substance of

two or more different chemically bonded

chemical elements, with a fixed ratio determining

the composition. (See the illustration above)

The ratio of each element is usually expressed bychemical formula.


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Compounds have different properties different

from its constituent elements. New substances are

formed.

For example, consider the compound WATER

(H2O)

Constituent elements: Oxygen (gas), Hydrogen (gas) BUT water is a liquid!

Oxygen supports burning and hydrogen is flammable

BUT water has no such properties!


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Compounds can be

broken down to simpler

substances by chemicalmethods.

For example,

Electrolysis of water to

produce oxygen gas andhydrogen gas respectively

(constituents of water)


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Making compounds

Compounds can be synthesized by:

1. Reacting two or more elements together

element

copper

(reddish-brown solid)

element

chlorine

(greenish-yellow

poisonous gas)

compound

copper chloride

(green solid)

element

Cu

element

Cl2compound

CuCl2


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Making compounds


1. Reacting two or more elements together

element element compound

element

magnesium

(silvery solid)

element

oxygen

(colourless gas)

compound

Magnesium oxide

(white solid)

2Mg O2 2MgO


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Making compounds


2. Reacting elements and compounds together

element

Iron fillings

(greyish solid)

compound

Dilute Sulphuric acid

(colourless liquid)

compound

Iron(II) sulphate

(green solid)

Hydrogen

(colourless gas)

compound

Fe H2SO4 FeSO4 H2


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Making compounds


3. Reacting two or more compounds together

compound

Sodium chloride solution

(colourless)

compound

Lead(II) nitrate solution

(colourless)

compound

Lead(II) chloride

(white solid)

Sodium Nitrate

(colourless solution)

compound

NaCl Pb(NO3)2 PbCl2 NaNO3


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In chemistry, a mixture is a substance made by

combining two or more different materials in

such a way that no chemical reaction occurs.

There is NO new substance formed.

There are 2 different types of mixtures:

Homogeneous (eg: Solution)Heterogeneous (eg: Suspension)


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As mixture is formed by physically mixing two

or more substances together, it does not have afixed ratio determining its composition.

In other words, the substances in a mixture can be

present in any amount variable proportion!


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A mixture still retains properties of the

constituents that make it up.

While there are no chemical changes in a mixture,

physical properties of a mixture, such as its melting

point, may differ from those of its components.

For example, a mixture of alcohol and water boils

over a range of temperatures.


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5.5 What are Mixtures?

A mixture consists of two or more different

substances that are mixed but not chemically

combined together. The substances that make up a mixture may be

elements, compounds or both elements and

compounds.


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Milk is a mixture of

compounds such as

proteins and fats.Airis a mixture of

elements, such as

nitrogen and oxygen,

and compounds

such as carbon

dioxide and water

vapour.

5.5 What are Mixtures?

Examples of mixtures:


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Properties of mixtures

Properties of mixtures Properties of air

When a mixture is formed,

no chemical reaction occurs.

Air is formed by simply mixing its

component gases nitrogen, oxygen,

carbon dioxide, noble gases and watervapour. No reaction occurs between the

components.

A mixture has the properties

of its constituent substances.

Air has the properties of its components

nitrogen, oxygen, carbon dioxide, noble

gases and water vapour. Air supports

combustion because the oxygen gas in it

supports combustion.


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Properties of mixtures

Properties of mixtures Properties of air

A mixture can be separated

easily by physical methods

(i.e. without involvingchemical reaction).

Air can be separated into its components

by fractional distillation.

The components in mixtures

are not mixed in any fixed

proportion.

The proportions of the constituent gases

in air may vary with place and time. For

example, we can find a higher amount of

carbon dioxide in the city than theseaside.


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Different types of mixtures

Solid-solid mixtures

o Alloys are mixtures of a metal element with other

metals or non-metals.

o An example is duraluminium which is a mixture of

aluminium and copper.

o It is strong and durable and often used in building

ships and aircraft engines.


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Alloys

o An alloy is a mixture of a metal and one or more

other elements. It has properties that are better than

those of its constituents.

o Examples of alloys:

Steel an alloy mainly composed of iron with a small

percentage of carbon

Brass copper-based alloy containing zinc

Bronze copper-based alloy containing tin


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Solid-solid mixtures

o Concrete is a mixture of cement and gravel.

o It is used in pavements, architectural structures,bridges, etc.


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Solid-liquid mixtures

o Calamine lotion is used for treating

skin rashes.

o It is made up of solid zinc oxide, solid

calcium hydroxide, liquid glycerine

and water.


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Solid-liquid mixtures

o Chendol is one of the

many types of drinks that

contain both solids and

liquids.


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Liquid-liquid mixtures

o Alcoholic drinks consist of ethanol and other

flavourings dissolved in water.

o Vinegaris made up of a solution of ethanoic acid

and water.

wine

vinegar


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Liquid-gas mixtures

o Most forms offoam that you see (e.g. in a cup of

cappucino or from a bubble bath ) are made up of air

bubbles in a liquid.


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Liquid-gas mixtures

o Soda drinks contain carbon dioxide dissolved in a

flavoured drink.


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In summary

Reaction

TypeA chemicalreaction required No chemicalreaction required

New

substance?New substances

formed.

No new substance

formed.

Breakdown

methodBy chemical

methods

By physical

methods


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Recommended websites.. Doc Brown's Chemistry Clinic

http://www.wpbschoolhouse.btinternet.co.uk/page

01/ElCpdMix/EleCmdMix.htm Mixture

http://en.wikipedia.org/wiki/Mixture

Mixtures & Compounds

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Mixtures.html#Properties_of_Mixtures


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Recommended websites.. Elements, Compounds & Mixtures

http://www.chem.purdue.edu/gchelp/atoms/elements

.html

Chem4Kids: Compounds & Mixtures

http://www.chem4kids.com/files/matter_mixture.html

http://www.chem4kids.com/files/atom_compounds.html


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Miscellaneous

http://en.wikipedia.org/wiki/Metals

http://en.wikipedia.org/wiki/Non-metals

http://periodic.lanl.gov/default.htm

http://www.teachnet.ie/macalvey/compound.htm

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Compounds Mixtures 2010

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