Science chapter 11 Flashcards by Lim Ze Qi Gwyneth (Nchs)

A mixture can be separated by

separated by physical
methods, e.g. filtration,
distillation or
chromatography.

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A compound can only be separated through

chemical reactions or by
using electricity.

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The chemical properties of a
mixture are

the same as those of its components.

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No chemical reaction takes
place when a

mixture is formed — usually there is
little or no energy change.

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The physical and chemical
properties of a compound
are

different from those of
the elements in the compound.

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A chemical reaction takes place when a

compound is formed — usually there is an energy change

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The components of a mixture
can be mixed in

any proportion.

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The elements in a compound
are always combined in a

fixed proportion (by mass).

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Changes can be classified as

physical changes or chemical changes

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Properties of physical changes (4 properties)

-No new substances are
formed
-No or little heat is taken in or
given out
-Properties of substance
remain the same
-Reversible

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Properties of Chemical changes (4 properties)

-One or more new substances
are formed (products)
-Heat and/or light energy may
be taken in or given out
-Properties of products are
different from starting
reactants
-Usually not easily reversible

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What is combustion

Combustion is a chemical reaction in which a
substance is heated in the presence of oxygen to
form one or more new substances.

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What is the law of conservation

The law of conservation of mass states that mass is always
conserved during a chemical reaction.

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Complete
combustion occurs
when there is an

abundant supply of
oxygen.

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What is thermal decomposition

Thermal decomposition is a
process in which a substance
is broken down into two or
more simpler substances upon
heating.

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During a reaction, mass cannot be…

created or destroyed

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What is usually given out during combustion

a lot of Heat and light energy

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What does oxidation refer to

Oxidation refers to a chemical change in which a
substance gains oxygen.

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Oxidation also occurs during

combustion and cellular respiration

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Organic acids are

weak acids

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What are two examples of an oxidation process

rusting and corrosion

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Mineral acids are

strong acids

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Acids have a

SOUR taste

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Acids are

corrosive

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Acids turn blue litmus paper

red

Acids dissolve in water to form solutions which can

conduct electricity. (electrolyte)

Alkalis taste... and have a ... feel

bitter, slippery

Alkalis turn red litmus paper

blue.

When alkalis react with acids, a chemical reaction called ... occurs? What is always formed

neutralisation occurs. Water is always formed.

acid + alkali ->

salt + water

Dilute acid + metals ->

salt + hydrogen

hydrochloric acid + sodium hydroxide 🡪 sodium chloride + water hydrochloric acid + potassium hydroxide 🡪 potassium chloride + water hydrochloric acid + calcium hydroxide 🡪 calcium chloride + water

REMEMBER

Hydrochloric acid(acid)+ sodium carbonate (carbonate)🡪

sodium chloride(salt) + carbon dioxide + water

HOW DO WE TEST FOR CARBON DIOXIDE GAS?

1. Add abt 2ml of hydrochloric acid and add 1 spatula of a carbonate to the acid in the test tube 2. put a stopper on the test tube 3. put abt 2ml of limewater into a separate test tube 4. then put a delivery tube into it 5. stopper end of the test tube with limewater goes into the test tube with carbonate and hydrochloric acid 6. shake to bubble gas into limewater 7. warm the test tube gently, moving side to side at the tip of the flame 8. if there is carbon dioxide, a white precipitate will form in the limewater

HOW TO TEST FOR HYDROGEN

Put a lit splint into the sample of the gas, if you get a squeaky pop sound when extinguished, it is hydrogen

pH below 7 =

acidic

pH 7 =

neutral

pH above 7 =

alkaline

acid ... .... in red litmus paper

remains red

A neutral solution ... ... in blue litmus paper

remains blue

A neutral solution ... ... in red litmus

remains red

In a universal indicator, strong acids , pH waht to waht , it will be

0 to 3, red

alkaline solution ... ... in blue litmus paper

remains blue

in weak alkali (pH waht to what ) it will be what colour

8 to 11, blue

In a universal indicator, in neutral solutions pH waht to waht, it will be variations of waht

6 to 8, green

In a universal indicator, weak acids, pH waht to waht, the colour will be waht tp waht

3 to 6, orange to yellow

strong alkali (pH waht+) it would be

11+, indigo or blue to dark purplle

In a Methyl Orange indicator, a strong acidic solution will be ... and a strong alkaline solution will be ...

red, yellow

In a Screened Methyl Orange indicator, a strong acidic solution will be ... and a strong alkaline solution will be...

violet, green

In a Phenolphthalein indicator, a strong acidic solution will be ... and a strong alkaline solution will be...

colourless, pink

Most plants grow best in ... soils.

neutral or slightly acidic

pH of soil may become unsuitable for plant growth due to:

-too much fertilisers added to the soil; -environmental pollution such as acid rain.

To treat acidity in soil, aka liming, add:

-calcium oxide (quicklime); -calcium hydroxide (slaked lime).

Mixing substances also produces other... changes.

chemical

Photosynthesis is the process

in which green plants produce glucose and oxygen from carbon dioxide and water using light energy.

Heat interacts with different substances to bring about

many different kinds of changes.

Photosynthesis is represented with this word equation

carbon dioxide + water ------------------------>glucose + oxygen light & chlorophyll

X rays are represented with this word equation

silver bromide--------------------------> silver + bromine x-ray or light

Cellular respiration is represented using the word equation

glucose + oxygen ----> carbon dioxide +water

Cellular respiration is the process

in which living cells of plants and animals take in oxygen to release the energy stored in glucose.

Passing an electric current through a substance also produces some chemical changes such as

electrolysis and electroplating

define electrolysis

Electrolysis is the chemical decomposition of substances with the passage of an electric current.

electrolysis is represented using the word equation

water --------------> hydrogen + oxygen electricity

Electroplating is an application of

electrolysis.

Electroplating is the process

in which a substance is coated with a metal with the passage of an electric current.

the knowledge of chemical reactions help us in our daily lives

through rusting, pollution and decomposition

Give me an example of electroplating

1. An electric current is passed through the copper sulfate solution. 2. The copper plate becomes smaller as the coin becomes coated with reddish brown copper.

Science chapter 11 Flashcards

(67 cards)