chemicals and chemical change

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CHEMICALS AND

CHEMICAL CHANGE

Chapter 5.1

BLM 5.1a, 5.1b

Chemicals and chemical Change

CHEMISTRY – is the study of matter, its changes and its properties

MATTER – is anything that has mass and takes up space

ATOM – the smallest particle of matter

PHYSICAL CHANGE – a change in a substance which does not produce a new substance.

• Easy to reverse

• Ex. Melting ice

CHEMICAL CHANGE – a change in a substance which does produce a new substance.

• Difficult to reverse

• Ex. Match burning

Classification of matter

Classification of matter

Classify each substance as 1) A pure substance or a mixture, and 2) An element, molecule, heterogeneous mixture or homogeneous: a) Glass of milk b) Spoonful of sugar c) A bar of gold d) Orange juice with pulp

Science 10 – Nov. 3 rd

Classify each reaction as a physical or chemical reaction: a) Butter melting b) Cheese molding c) Breaking a chocolate bar in half d) Burning toast

Science 10 – Nov. 3 rd

Classify each substance as 1) A pure substance or a mixture, and 2) An element, molecule, heterogeneous mixture or homogeneous: a) Glass of milk b) Spoonful of sugar c) A bar of gold d) Orange juice with pulp

Physical Reaction vs. Chemical

Reaction

Physical reactions are easy to reverse while chemical reactions are not.

• Ex “When ice melts is it easy to reverse that reaction? Burning a match?”

Physical Trait vs. Chemical Trait

Physical traits are either simple observations or things having to do with physical reactions.

• Color, smell, size, mass, boiling point, melting point.

Chemical traits have to do with chemical reactions.

• Will it catch on fire?

• Ability to react with other chemicals.

• Stable or unstable.

Science 10 – Nov. 1 st

1) Classify each as 1) Pure substance or mixture, then 2) Element, compound, homogeneous mixture or heterogeneous mixture .

a) b) c) d) e)

Sugar

Copper wire

Air

Orange juice w/ pulp

Orange juice w/o pulp

Science 10 – Nov. 1 st

2) Classify each as a physical change or a chemical change: a) b) c) d) e)

Food rotting

Breaking a carrot in half

Water boiling

Making toast

Dissolving salt into water

Science 10 – Nov. 1 st

3) Classify each as a physical trait or chemical trait: a) b) c) d) e)

Water freezes at 0 o C

Ethanol is a clear liquid

Gold does not react with acid

Aluminum is a malleable metal

Mercury metal is a liquid at room temperature

HOMEWORK QUESTIONS

Page 175

QUESTIONS: #1,2,4,5,6,7

Explain in your own words the difference between element, atom, molecule and compound.

Work on project

SOLUTIONS TO HOMEWORK

QUESTIONS

Q1 – classify each of the following as a pure substance or a mixture

A) soapy water

MIXTURE

B) hydrogen gas

PURE SUBSTANCE

C) sodium chloride

PURE SUBSTANCE

QUESTION 2

Classify each of the following as an element or a compound.

A) hydrogen

ELEMENT

B) potassium carbonate

COMPOUND

C) water

COMPOUND

D) Mg

ELEMENT

QUESTION 4

Classify each of the following as a physical property or a chemical property.

A) Gasoline is a clear pink solution

PHYSICAL PROPERTY

B) Gasoline burns in air

CHEMICAL PROPERTY

C) Water boils at 100 0 C.

PHYSICAL PROPERTY

D) electric current can split water into hydrogen and oxygen gases

CHEMICAL PROPERTY

QUESTION 5

When aluminum metal is added to hydrobromic acid, hydrogen gas and an aluminum bromide solution are formed.

A) What kind of change has occurred?

A chemical change has occurred because new substances were made.

QUESTION 5

When aluminum metal is added to hydrobromic acid, hydrogen gas and an aluminum bromide solution are formed

B) Which substances are the reactants and which are the products?

Reactants – Aluminum and Acid

Products – Hydrogen + Aluminum Bromide

QUESTION 6

Describe the chemical tests that can be used to identify the following gases.

A) hydrogen a flaming wooden splint causes a “pop”

B) Oxygen a glowing wooden splint relights (bursts into flame)

QUESTION 6

C) Carbon Dioxide

A burning wooden splint extinguishes, OR when the gas is bubbled through limewater, the limewater changes from a clear, colourless solution to a cloudy white liquid (a precipitate is formed)

QUESTION 6

d) Water Vapour

Changes the colour of cobalt chloride test paper from blue to pink

QUESTION 7

When sodium carbonate is added to water, the sodium carbonate dissolves.

When hydrochloric acid is added to the solution, the solution fizzes. What kinds of changes have occurred?

QUESTION 7 - ANSWER

When sodium carbonate dissolves in water it is a physical change

A chemical change happens when gas is formed after hydrochloric acid is added

( fizz / Bubbles )

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