chem test - 3/27/24

Question 1

What is the Law of Conservation of Mass?

Answer 1

Atoms can only be rearranged in a chemical reaction, not created or destroyed, leading to the conservation of mass where the mass of reactants equals the mass of products, only in a closed system.

Question 2

What are open systems?

Answer 2

Systems that allow matter to enter or leave, potentially altering the total mass while still adhering to the law of conservation.

Question 3

What are closed systems?

Answer 3

Systems that do not allow matter to enter or leave, maintaining a constant mass according to the law of conservation, though energy may change forms.

Question 4

What is a synthesis reaction?

Answer 4

Reactions where smaller molecules combine to form larger molecules, represented by A + B → AB.

Question 5

What is a decomposition reaction?

Answer 5

Reactions where large molecules break down into elements or smaller molecules, represented by AB → A + B.

Question 6

What is a single displacement reaction?

Answer 6

Reactions where a single element displaces another element in a compound, represented by Z + AB → ZB + A.

Metals can only replace other metals

Question 7

What is double displacement reaction?

Answer 7

Reactions where elements exchange places within compounds, represented by AB + BC → BB + AC.

Question 8

What is a combustion reaction?

Answer 8

Reactions where a fuel reacts rapidly with oxygen, producing oxides and energy, potentially resulting in complete or incomplete combustion.

Question 9

What is an acid?

Answer 9

Aqueous solutions that produce H+ ions, characterized by sour taste, reactivity with metals, and ability to change colors of indicators.

Question 10

What is a base?

Answer 10

Aqueous solutions that produce OH- or CO32- ions, characterized by bitter taste, slippery feel, and ability to conduct electricity.

Question 11

What is the pH scale?

Answer 11

Measure of acidity or basicity on a scale from 0 to 14, where pH less than 7 indicates acidity, 7 indicates neutrality, and greater than 7 indicates basicity.

Question 12

What are acid-base indicators?

Answer 12

Substances that change color based on the acidity or basicity of a solution, such as litmus paper.

Question 13

What is neutralization?

Answer 13

Reaction between an acid and a base to form water and an ionic compound, resulting in a pH closer to 7.

Question 14

What happens in neutralization reactions?

Answer 14

Double displacement reactions where acids and bases react to produce water and a salt.

Question 15

What are the products in complete combustion?

Answer 15

Hydrocarbon + oxygen → carbon dioxide + water + energy

Question 16

What are the products in incomplete combustion?

Answer 16

Hydrocarbon + oxygen → carbon dioxide + water + carbon monoxide + carbon + energy

Question 17

What is the difference between rust and corrosion?

Answer 17

Corrosion: Breakdown of a metal as a result of chemical reactions with its environment.
Rusting: One form of corrosion; the corrosion of metals that contain iron.

Question 18

What causes rust? What prevents it?

Answer 18

Causes: Corrosion of iron affected by air, water, electrolytes, acidity
Prevention: use corrosion resistant materials, such as plastic or paint, protective coating and galvanizing steel.

Question 19

Corrosion: How does salt contribute to the condition of the car?

Answer 19

It can affect both the bodies of cars and the metal supports of bridges as salt speeds up the process of corrosion once it begins. Salt can create more rust on cars that have already been corroded.

Question 20

Corrosion: What have car companies done differently from the past to avoid rusting on bumpers?

Answer 20

They have began to make bumpers out of plastic rather than steel as it doesn’t corrode and is much lighter than steel

Question 21

Corrosion: How does this strategy benefit the environment?

Answer 21

It can reduce the release of metal pollutants and conserve the resources used in steel production that can be very wasteful and harmful

Question 22

Corrosion: What is meant by beneficial corrosion and how does this differ from rusting?

Answer 22

Beneficial corrosion happens when metals like aluminum or copper develop protective coatings like aluminum oxide or greenish patina, protecting the metal from further damage. In contrast, rusting is the corrosion of iron, where the rust layer doesn’t protect the metal but continues to degrade it.

Question 23

What is the optimal pH range for swimming pools?

Answer 23

7.2-7.8

Question 24

What happens if pH drops below this optimal range?

Answer 24

Water irritates the eyes

Question 25

What chemical can be used to fix pH level drop in swimming pools?

Answer 25

Products containing sodium carbonate can be added to raise the pH when it is too low

Question 26

What are the compounds causing acid precipitation?

Answer 26

Sulfur dioxide and nitrogen oxides

Question 27

What are the major sources that produce these compounds in Canada?

Answer 27

Industrial processes like burning coal for electricity generation, smelting metals and vehicle emissions from burning fossil fuels

Question 28

What are the economical impacts of acid precipitation in Canada?

Answer 28

Damage to forests, steel structures, limestone buildings, stone monuments and losses in wood production and recreational fishing

Question 29

What are the methods or regulations that help to reduce the emission of the acid precipitation causing compounds in North America?

Answer 29

Switching to low-sulfur fossil fuels, installing scrubbers on smokestacks, improving pollution control equipment on vehicle and enacting stricter anti-pollution laws like Ontario’s Drive Clean Program

Question 30

Name the properties of bases

Answer 30

bitter taste, slippery feel, 7-14 pH, ionic compounds; ions released when aqueous, good conductors of electricity, water soluble, corrosive

Question 31

Name the properties of acids

Answer 31

sour taste, water soluble, reacts with metals to release hydrogen gas, reacts with carbonates to release carbon dioxide gas, good conductors of electricity, pH scale of 1-6 (more hydrogen ions released when aqueous = strong acid = low pH)

Question 32

Acid-base indication (litmus paper)

Answer 32

Red litmus paper:
Turns blue if acidic
Remains red if neutral
Remains red if basic

Blue litmus paper:
Remains blue if acidic
Remains blue if neutral
Turns red if basic

Question 33

Acid-base indication (bromothymol blue)

Answer 33

Colour in acid = yellow
Colour in base = blue

Question 34

Acid-base indication (phenolphthalein)

Answer 34

Colourless = acid
Pink = base

Question 35

Acid-base indication (phenol red)

Answer 35

Yellow = acid
Red/pink = base

Question 36

Acid-base indication (methyl orange)

Answer 36

Red = acid
Orange/yellow = base

Question 37

Acid-base indication (cabbage juice)

Answer 37

Red/pink = acid
Green/yellow = base