Question

CHAPTER 3 WATER AND THE FITNESS OF THE ENVIRONMENT Learning objectives The Properties of Water 1. With the use of a diagram or diagrams, explain why water molecules are: a. polar b. capable of hydrogen bonding with 4 neighboring water molecules 2. List four characteristics of water and explain why they result from hydrogen bonding, 3. Define cohesion and adhesion. Explain how water's cohesion and adhesion contribute to the movement of water from the roots to the leaves of a tree. 4. Distinguish between heat and temperature. Relate to molecular motion. 5. Use some of these as examples in referring to the properties of water: Coastal areas have milder climates than adjacent inland areas. Ocean temperatures fluctuate much less than temperatures on land. Insects like water striders can walk on the surface of a pond without breaking the surface. If you slightly overfill a water glass, the water will form a convex surface above the top of glass. If you place a paper towel so that it touches spilled water, the towel will draw in the water. Ice floats on water. Humans sweat and dogs pant to cool themselves on hot days. The Solvent of Life 6. Distinguish between a solute, a solvent and a solution. 7. Distinguish between hydrophobic and hydrophilic substances. The Dissociation of Water Molecules 8. Name the products of the dissociation of water and give their concentration in pure water. 9. Define acid, base, and pH. 10. Determine the pH of a solution if the concentration of hydrogen or hydroxide ions is know

pls answer all ??

Answer 1

1.(a) Water molecule is composed of two hydrogen molecule and one oxygen molecule. Oxygen is highly electronegatively charged molecule and hydrogen are positively charged molecules. Due to its bent shape water molecules are polar in nature.

(b) Water molecules are capable of hydrogen bonding with 4 neighbouring water molecules because of its polar nature which causes the interaction of positively charge hydrogen atom to combine with negatively charged oxygen atom of other water molecule. This interaction is called hydrogen bonding.

2. Four characteristics of water molecules are:

Water are polar molecules.

Water have high specific heat capacity.

Water have high vaporisation of ice.

Water are cohesive and adhesive in nature.

Water due to its polar nature capable of binding negative charged oxygen atom to the positive charged hydrogen atom by polar covalent bond. Hence water molecules results from hydrogen bonding.

3. Cohesion is defined as the attraction between the molecules of the same substances.

Adhesion is defined as the attraction between the two different substances.

Due to cohesive property of water, water molecules attracts to each other and form a cling in the xylem tube of a plant. Further adhesive property of water allows the movement of water in the upward motion contributing to the movement of water from the roots to the leaves of the tree.

4. The measure of total energy of the molecular motion in a molecule is defined as heat.

The measure of the average energy of the molecular motion in a molecule is defined as temperature.

6. Solute is a substance that is dissolved in a solution.

Solvent is a liquid in which a solute is dissolved.

Solution is a liquid containing solute and solvent .

7. Hydrophobic substances are those substances which do not attract to water molecules.

Hydrophilic substances are those substances which attracts towards water molecules.

8. The products of the dissociation of the water are hydrogen molecules ( H_{​​​​​​3}​​O​+) and hydroxide ions (OH^{​​​​​-}​).

Their concentration in pure water is 1*10⁷ M.

9. Acid is a substance that produce hydrogen ions .

Base is a substance that produce hydroxide ions.

Ph is a measure of hydrogen ion concentration in a solution.

10. Ph is equal to the negative value of the logarithm to the base 10 of the concentration of the hydrogen ions.