1) Water

a) Water is the most important liquid; why?

b) Discuss water properties. You need to include at least the following properties: physical properties (color, density, water phases, boiling point, melting point), chemical properties (formula, bond type, pH), properties of ice.

c)What are the most important water pollution factors?

2. Define the acids, bases, and the pH. Using the pH scale give examples of acids, bases, and neutral solutions.

Water is known for being the "universal solvent" because it dissolves any substances than any other liquid. It is also an essential element in Earth due to its usefulness and benefits for human being. Water is also necessary for the agricultural, industrial, household and environmental activities.

Water Properties

Physical properties

Molar mass = 18.0151 grams per mole

Melting point = 0.00 degree Celsius

Boiling Point = 100.00 degree Celsius

Maximum density (at 3.98 degree celcius) = 1.0000 grams per cubic centimetre

density (25 °C) = 0.99701 grams per cubic centimeter

vapour pressure (25 °C) = 23.75 torr

heat of fusion (0 °C) = 6.010 kilojoules per mole

heat of vaporization (100 °C) = 40.65 kilojoules per mole

heat of formation (25 °C) = −285.85 kilojoules per mole

entropy of vaporization (25 °C) = 118.8 joules per °C mole

viscosity = 0.8903 centipoise

surface tension (25 °C) = 71.97 dynes per centimeter

Chemical Properties

Acid-base reactions

·       Water undergoes different types of chemical reactions

·      ability to behave as both an acid (a proton donor) and a base (a proton acceptor)

·      H₂O(l) + H₂O(l) ? H₃O⁺(aq) + OH⁻(aq) - represents the liquid state

·      According to the Britannica, when an acid (a substance that can produce H⁺ ions) is dissolved in water, both the acid and the water contribute H⁺ ions to the solution. This may result to a situation where the H⁺ concentration is greater than 1.0 × 10⁻⁷ M. Since it must always be true that [H⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 25 °C, the [OH⁻] must be lowered to some value below 1.0 × 10⁻⁷.

·      The mechanism for reducing the concentration of OH⁻ involves the reactionH⁺ + OH⁻ → H₂O,

C. IMPORTANT FACTOR OF WATER POLLUTION

·      One of the known factors for water pollution is the boom of industrialization. This is because there will be an excessive production of domestic waste, radioactive, pesticides or fertilizers for agricultural purposes and also the population growth. Due to the improper disposal of such materials, water became contaminated causing the marine or human life to be prone in death or diseases.

D. ACID, BASES AND PH SCALE

·      Acid refers to the substance where it donates hydrogen ions. This is where a base is dissolved in water to balance with the hydrogen. If there will be a hydrogen ions that hydroxide ions, the solution is considered as acidic.

·      Base refers to a substance where it accepts hydrogen ions. This is where the base is dissolved in water to balance the hydrogen ions and hydroxide ions to shift in different ways. If the solution is more in hydroxide ions, the solution is considered as alkaline.

·      PH refers to the acidity and alkalinity of a certain solution that is measure using the logarithmic scale.

Follow the format:

Ph Value - H+ concentration - Example

0 - 10,000,000 - Battery acid

1 - 1,000,000 - Gastric acid

2 - 100,000 -Lemon juice, vinegar

3 - 10,000 - Orange juice, soda

4 - 1,000 - Tomato juice, acid rain

5 - 100 - black coffee, bananas

6 - 10 - Urine, milk

7 - 1 - Pure water