chemicals and chemical change

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 milkb) Spoonful of sugar

c) A bar of goldd) Orange juice with pulp

Science 10 – Nov. 3rd

Classify each reaction as a physical or chemical reaction:a) Butter meltingb) Cheese molding

c) Breaking a chocolate bar in halfd) Burning toast

Science 10 – Nov. 3rd

Classify each substance as 1) A pure substance or a mixture, and 2) An element, molecule, heterogeneous mixture or homogeneous:a) Glass of milkb) Spoonful of sugar

c) A bar of goldd) 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. 1st

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

a) Sugarb) Copper wirec) Aird) Orange juice w/ pulpe) Orange juice w/o pulp

Science 10 – Nov. 1st

2) Classify each as a physical change or a chemical change:

a) Food rottingb) Breaking a carrot in half c) Water boilingd) Making toaste) Dissolving salt into water

Science 10 – Nov. 1st

3) Classify each as a physical trait or chemical trait:

a) Water freezes at 0oCb) Ethanol is a clear liquidc) Gold does not react with acidd) Aluminum is a malleable metal e) 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 2Classify each of the following as an element

or a compound.A) hydrogen

ELEMENTB) potassium carbonate

COMPOUNDC) water

COMPOUNDD) Mg

ELEMENT

QUESTION 4

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

A) Gasoline is a clear pink solutionPHYSICAL PROPERTY

B) Gasoline burns in airCHEMICAL PROPERTY

C) Water boils at 1000C. PHYSICAL PROPERTY

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

QUESTION 5When 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 5When 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 AcidProducts – Hydrogen + Aluminum

Bromide

QUESTION 6Describe 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 6C) 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 6d) Water Vapour

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

QUESTION 7When 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 - ANSWERWhen sodium carbonate dissolves in

water it is a physical changeA chemical change happens when gas

is formed after hydrochloric acid is added ( fizz / Bubbles )