2. Chemistry of Seawater

Question 1

Define conservative elements

Answer 1

They are elements whose ratios to each other remains constant.

Question 2

How many times is salwater more saltier than freshwater?

Answer 2

220 times!

Question 3

Define mole and what is it equal to?

Answer 3

A mole is a chemical term referring to an amount of a substance.

It is equal to 6.02 x 10^23.

Similar to dozen=12.

Question 4

True/False

Ocean salt is so complicated that no lab in the world can reproduce it from its basic 80 chemicals.

Answer 4

True

Ocean is very complex and is made of 100minerals composed of 80 checmical elements.

Question 5

How many g of salt are there in a kg of seawater?

Answer 5

35g salt per 1kg of seawater

Question 6

What are the six constituents of the ocean (and their symbols)?

Cations

Anions

Answer 6

Cations:

1. sodium (Na⁺)
2. magnesium (Mg ²⁺)
3. Calcium (Ca ²⁺ )
4. Potassium (K⁺ )

Anions:

1. chloride (Cl^- )
2. sulphate (SO4^2- )

Question 7

How can we find mole ratio?

Answer 7

By looking at the coefficients of constituents in a dissociation equation.

Question 8

Give two examples of a dissociation equation and their mole ratios.

Answer 8

CaCl_² ⇒ Ca²⁺ + 2Cl ^- 1:1:2

K₂SO₄ ⇒ 2K⁺ + SO₄^2- 1:2:1

Question 9

List the rules to naming ionic compounds

Answer 9

• Name the metal first
• The anion has -ide added
• Use roman numerals if anion has a subscript
• Use brackets when necessary
• If more than two types of elements are present they are polyatomic ions
• If two polyatomic ions are present name both

Question 10

Name these ionic compounds:

1. NaF
2. BaCl₂
3. Li₂O
4. ZnCl₂
5. Al₂(CO₃)₃
6. (NH₄)₂SO₄

Answer 10

1. sodium fluoride
2. barium (II) chloride
3. lithium oxide
4. zinc (II) chloride
5. aluminium (III) carbonate
6. ammonium sulphate

Question 11

Write the formula for the following:

1. Copper (I) chloride
2. Copper (I) carbonate
3. ammonium sulphate
4. ammonium phosphate

Answer 11

1. CuCl
2. Cu₂CO₃
3. (NH4)₂SO₄
4. (NH4)₃PO₄