Environmental Chemistry

Question 1

List the three major consitiuents within the atmosphere:

Answer 1

Nirtrogen: 78%

Oxygen: 20%

Argon: ≈.97%

Question 2

Define ozone and state its importance

Answer 2

Ozone- O₃formed through the collision of elemental oxygen, O, and diatomic oxygen, O_2:

O_(g) + O_2(g) → O_3(g)

• Ozone prevents harmful wavelengths of UV light from passing through Earth’s atmosphere
  
  • Without ozone, damaging rays would reach the planent and destroy plant and animal life

Question 3

What is the greenhouse effect?

Answer 3

Sunlight reflected from the earth’s surface is absorbed by greenhouse gases, retaining heat and raising temperature on earth

Question 4

Define and name four common greenhouse gases:

Answer 4

Water vapour, carbon dioxide, nitrous oxide, and ozone

Question 5

Define CFCs and its negative impacts on the atmosphere:

Answer 5

• CFCs (chloroflurocarbons) are a manmade chemical compound consisting of chlorine, flourine, and carbon
• CCl₂F₂ also became known as freon gas
  
  • Freon gas is associated with the depletion of ozone through a series of chemical reactions:

CCl₂F₂ →_{(light energy)} CClF_2(g) + Cl(CFCs react with light energy to form free chlorine)

Cl_(g)+ O₃ → ClO_(g) + O_2(g)

O_(g) + ClO_(g) → Cl_(g) + O_2(g)

O_(g) + O_3(g) → O_2(g)

Question 6

Analyze reaction between calcium carbonate and sulfuric acid

Answer 6

CaCO_3(s)+ H₂SO_4(aq)→ Ca²⁺_(aq)+ CO₃^2-_(aq) + H₂SO_4(aq)

→ Ca²⁺_(aq) + H₂CO_{3(aq) +}SO₄^2-_(aq)(H₂CO₃ breaks up due to unstability)

→ Ca²⁺_(aq) + H₂O_(l) + CO_2(g)+ SO₄^2-_(aq)

Full equation: CaCO_3(s) + H₂SO_4(aq) → CaSO₄ + H₂O_(l) + CO_2(g)

Question 7

Define Acid Rain:

Answer 7

Rain that has a low pH because of certain oxides polluted by human activities

Question 8

What is the cause of acid rain?

Answer 8

Acid rain is formed when sulfur and nitrogen oxides combine with moisture in the air to form sulfuric acid and nitric acids.

• SO₂ reacts with ozone or diatomic oxygen molecules to form SO₃, is SO₃ then reacts with moisture to form sulfuric acid:

SO_3(g) + H₂O_(l) → H₂SO_4(aq)

• Nitrogen dioxides react with mositures found in the air to form nitric acid

2NO_2(g) + H₂O_(l) → HNO_2(aq)+ HNO_3(aq)

Question 9

How are nitrogen and sulfur oxides produced?

Answer 9

• SO₂ is produced by coal and oil combustion
• NO_x (denotes a mono-nitrogen oxides: NO and NO₂₎) is produced by coal and gasoline combustion by cars

Question 10

Chemical formula for Marble?

Answer 10

CaCO₃ (Calcium Carbonate)

Question 11

Chemical formula for mineral lime?

Answer 11

CaO

Question 12

List basic properties of Calcium Carbonate:

Answer 12

• Reacts readily with acids
• Heating limestone produces carbon dioxide, leaving CaO (lime)
• Does not reat with water
• Reacting hydrochloric acid with limestone produces a salt solution, carbon dioxide, liquid water, and heat:

CaCO_3(s) + 2HCL_(aq)→ CaCl_2(aq) + CO_2(g) + H₂O_(l) + Heat

• Limestone can be prepared by reacting carbon dioxide with a calcium hydroxide solution:

Ca(OH)_2(aq) + CO_2(g) → CaCO_3(s) + H₂O_(l)

Question 13

List basic properties of Calcium Oxide:

Answer 13

• Basic
• Adding water to calcium oxide produces calcium hydroxide in an exothermic reaction:

CaO_(s) + H₂O_(l) → Ca(OH)_2(s)

Question 14

Chemical formula for Slaked Lime?

Answer 14

Ca(OH)₂ (Calcium hydroxide)

Question 15

List basic properties of Slaked Lime:

Answer 15

• Basic
• Dissolves in water producing an alkaline solution called limewater