Chapter 11- Chemical Changes

Question 2

Properties of physical changes

Answer 2

A change in which no new substances was formed

Question 3

Properties of chemical changes

Answer 3

New substances in the form of elements or compounds are formed

The processes are not easily reversed

energy is sometimes taken in or given out in chemical reactions

Question 4

What are substances that react with each other called in a chemical change

Answer 4

reactants

Question 5

What are new substances formed from a chemical change called

Answer 5

products

Question 6

What are the 2 main types of chemical changes known as

Answer 6

1) Combination (2 or more reactants form one product)
2) Decomposition (one reactant form 2 or more products)

Question 7

Properties of physical change

Answer 7

1) no new substances are formed
2) Changes can usually be reversed through separation techniques

Question 8

Word equations are written as…

Answer 8

reactants (arrow) products

Can be 2 or more reactant or products
Can write chemical process that occured above the arrow if needed

Question 9

During a chemical reaction, atoms of the reactants…

Answer 9

are neither destroyed or created, but rearranged instead

Conservation of mass

Question 10

Define combustion

Answer 10

Combustion is a chemical process where substances are burned or heated with oxygen to form one or more new substances

COMBINATION

Question 11

Define thermal decomposition

Answer 11

The process in which a substance breaks down into two or more simpler substances upon heating

DECOMPOSITION

Question 12

Define oxidation and state the effects of the two main forms of oxidation

Answer 12

Oxidation is a COMBINATION type process in which a chemical change occurs when an object is in contact with oxygen

1) Rusting- Iron reacts with oxygen to form iron oxide (rust)
2) Cellular respiration- nutrients such as glucose are broken down in the presence of oxygen to provide cells with energy to survive and reproduce

Question 13

Properties of acids

Answer 13

1) sour taste
2) some are corrosive
3) turn blue litmus paper red
4) reacts with alkali, carbonates, and metals

Question 13

Properties of alkali

Answer 13

1)bitter taste
2)soapy feel
3)some are corrosive
4)turns red litmus paper blue
5)reacts with acids

Question 14

Define neutralisation

Answer 14

When an acid and an alkali reacts to form salt and water

Question 14

Define salt

Answer 14

Salt is a general term for a compound containing an element that is metal

Question 15

What do acids and metals form

Answer 15

salt + hydrogen gas

Question 16

Naming of salt is always based on

Answer 16

Metal available in the chemical reaction + acid type

Question 17

Test for hydrogen gas

Answer 17

Placing a lighted splint above the test tubes. In the presence of hydrogen, lighted splint will extinguish

Question 18

Acids and carbonates, when reacted, form

Answer 18

Salt + water + carbon dioxide gas

Question 19

Test for carbon dioxide gas

Answer 19

Effervescence observed when bubbling the gases in the reaction with limewater
– a white precipitate will form in the presence of carbon dioxide

Question 20

pH 14 is known to be very x, and very concentrated with y

Answer 20

x= basic
y= hydroxides

Question 21

pH scale from x to y

Answer 21

x = 0
y = 14

Question 22

pH 0 is known to be very x, and highly concentrated with y

Answer 22

x= acidic
y= hydrogen molecules

Question 23

Universal indicator go from x to y to z to a to b to c when going from pH 0-14

Answer 23

x= red y= orange z= yellow a= green (neutral) b= blue c= purple

Question 24

pH value x is neutral

Answer 24

x=7

Question 25

litmus paper remains the same colour when x or y occurs

Answer 25

x= acidity or alkhalinity corresponds with colour of the paper y= substance is neutral (salts and water)

Question 25

Mixing allows x to occur

Answer 25

x=chemical changes

Question 26

expoure to light allows x or y to occur

Answer 26

x=photosynthesis , a chemical reaction y= fading of colours in clothes, a chemical reaction

Question 27

Cooking causes x in foods

Answer 27

x= chemical changes | chemical changes are the reason why foods are softer after being cooked

Question 27

usage of electric current allow x to occur

Answer 27

x=electroplating (one material degradades and one material combines)

Question 28

Respiration occurs when x and y combines together to form carbon dioxide and water molecules. The large amount of energy released in this reaction is what allows cells to live

Answer 28

x= glucose y= oxygen

Question 29

Decay is the process of x | decay allows nutrients to return back to the environment

Answer 29

x= breaking down of organic matter into simpler substances

Question 29

Combustion produces x

Answer 29

x= air pollutants such as carbon monoxide

Question 30

combustion causes x

Answer 30

x= increase in co2 in atmosphere results in global warming results in climate change results in acidification of oceans

Question 31

Acidification of ocean occurs due to x

Answer 31

x= large amounts of CO2 in the atmosphere dissolving in the sea water, forming carbonic acids

Question 32

ocean acidification are bad for x and y

Answer 32

x= animals y=plants death will occur

Question 33

ocean acidification is a result of x

Answer 33

x=chemical reactions arising from human activities | more plants could lessen the impact of this issue