Aquatic Ecosystem Lesson 1 PDF

Aquatic Ecosystem Lesson 1  Aquatic Aquatic Ecosystem Ecosystem The effects of chemical reactions on the quality of water : Water’s unique properties make it vital for life - Its ability to dissolve many chemical substances - It exist in...

Aquatic Ecosystem Lesson 1  Aquatic Aquatic Ecosystem Ecosystem The effects of chemical reactions on the quality of water : Water’s unique properties make it vital for life - Its ability to dissolve many chemical substances - It exist in 3 different states Solid, liquid and gas (within the temperature). Water 70% It is essential for all living things, Land 30% from tiny microbes to large animals. It moves into cells, providing nutrients and removing waste. 1.Atmosphere 2. Geosphere as water exists in Water as water vapour is from the solid state in the components of cryosphere, which atmosphere in refers to the frozen gaseous state exist in: water in the polar regions, icebergs, and glaciers 3. Hydrosphere Water covers about 70% of the Earth’s surface. 1st Sec 2 Integrated Science  Aquatic Ecosystem Water Salty water Fresh water (about 97 %) : Only a small portion is freshwater found existing in oceans, seas, in rivers, lakes, and underground. Water and saltwater lakes. vapor contributes to the atmosphere, while frozen water, is found in polar regions and glaciers Percent of water to land on Earth’s Earth’s surface water 3% 30% Land Fresh water Water 70% 97% Salt water 1. Evaporation The Hydrological water evaporates from water bodies cycle in nature & the biological processes such as transpiration in plants and respiration in plants and animals contribute in this process too then rise into the 2. condensation atmosphere water condenses to form clouds 3. preciptation rain or snow falls 4. collection again to form water bodies water seepage through the pores of soil and Water vapor in clouds may react ‫ع‬ sedimentary rocks to form chemically with compounds in the groundwater. air, forming acids that fall as acid rain, which dissolves rocks Integrated Science 3 1st Sec  Aquatic Ecosystem Chemical Structure H2O Water is composed of two elements: hydrogen and oxygen. By volume By Mass hydrogen and oxygen oxygen accounts for approximately combine in a 2:1 ratio 88.89% of a water molecule, while hydrogen constitutes about 11.11% However, The two hydrogen atoms are covalently bonded to a single oxygen atom with a bond angle of approximately 104.5° degrees. 1st Sec 4 Integrated Science  Aquatic Ecosystem Test yourself 1- Which of the following represent the percent of fresh water on Earth? a) 50 % b) 3 % c) 70 % d) 97 % 2-The water cycle in nature is called : a) Biological b) Hydrogenic c) Hydrological d) Chemical 3-The type of bond between hydrogen and oxygen within water molecules is : a) Ionic bond b) Covalent bond c) Metallic bond d) Hydrogen bond The chemical structure: Water, as found on Earth, is rarely pure. It typically contains various ions and chemical substances that interact with it in numerous ways. Let’s explore three of water’s primary chemical properties: 1-Polarity : The oxygen atom in a water molecule has a much higher electronegativity than the hydrogen atoms. This causes the electrons in the covalent bonds to be pulled more strongly towards the oxygen atom. As a result, the oxygen atom carries a partial negative charge (0-), while the hydrogen atoms carry partial positive charges (8+). This uneven distribution of charge gives the water molecule a polar character. It allows water to dissolve a wide range of substances, transport nutrients, and participate in numerous biological processes. ‫ع‬ Integrated Science 5 1st Sec  Aquatic Ecosystem Example: Salt (NaCl) dissolves in water because the positive sodium ions are attracted to the negative oxygen end of water molecules, while the negative chloride ions are attracted to the positive hydrogen end. The ability of water molecules to form hydrogen bonds with each other is a primary reason for the high boiling point of pure water, which reaches 100 degrees Celsius under standard atmospheric pressure. This is in contrast to compounds with similar structures, such as hydrogen sulfide, which boils at -61 degrees Celsius. 1st Sec 6 Integrated Science  Aquatic Ecosystem 2-Hydrolysis : small percentage of water molecules exist as hydrogen ions (H+) and hydroxide ions (OH-). Chemical reactions with various compounds can cause hydrolysis of certain salts present in natural water, affecting the balance of these ions and resulting in the acidity or alkalinity of the water. Practical Example: - When table salt (NaCI) is added to water, it dissociates into sodium ions (Na+) and chloride ions (CI). These ions remain in the solution without interacting with water ions, making the solution neutral because the concentration of hydrogen ions (H+) is equal to the concentration of hydroxide ions (OH-). - However, in the case of sodium bicarbonate (NaHCO3), hydrolysis occurs, leading to a decrease in the concentration of hydrogen ions (H+) and an increase in the concentration of hydroxide ions (OH-) making the salt solution basic. HCO3 + H2O → HCO3 + OH ‫ع‬ Integrated Science 7 1st Sec  Aquatic Ecosystem The opposite occurs when ammonium chloride (NH4CI) is dissolved in water, which undergoes hydrolysis and causes a decrease in the concentration of hydroxide ions and an increase in the concentration of hydrogen ions, making the salt solution acidic. NH4+ + H2O → NH3 + H3O+ 3- Acid – base balance : - The acid-base balance in water depends on the relationship between the concentration of hydrogen ions (H+) and hydroxide ions (OH-). This relationship can be determined by measuring the pH of the solution. pH is a scale ranging from 0 to 14. If the concentration of H+ ions increases, the water becomes acidic and the pH value is less than 7. Conversely, if the concentration of OH- ions increases, the water becomes basic and the pH value is greater than 7. When the concentrations of H+ and OH ions are equal, the water is neutral and the pH value is 7. PH : is a measure of how acidic or basic a solution is. Pure water has a ph of approximately 7, which is considered neutral. However, this value can vary in natural environments, affecting the organisms that live there.” 1st Sec 8 Integrated Science  Aquatic Ecosystem pH 1. Examples: The pH of seawater generally ranges from 7.5 to 8.4, depending on the specific location and surrounding environmental factors. 2. Freshwater in rivers and lakes typically has a pH range of 6.5 to 8.5. 3. Distilled water has a pH of approximately 7, as it is devoid of most impurities and ions that contribute to the acidity or alkalinity of other natural water sources. 4. The pH of groundwater varies from one region to another, primarily due to the underlying rock composition. Groundwater is often neutral or alkaline, with pH values influenced by the presence of calcium carbonate or magnesium carbonate rocks. 5. Cloud water is generally slightly acidic, with a ph ranging from 4.5 to 5. This acidity is primarily due to the presence of dissolved carbon dioxide and other acidic gases in water droplets.” ‫ع‬ Integrated Science 9 1st Sec  Aquatic Ecosystem Test yourself 1- Which of the following represent the percent of salty water on Earth? a) 50 % b) 3 % c) 70 % d) 97 % 2-The ph of distilled water equals approximately : a) 5 b) 6 c) 7 d) 8 3- When ammonium chloride (NH4CI) is dissolved in water , the salt solution becomes : a) alkaline b) acidic c) neutral d) all of the above 4- When sodium bicarbonate (NaHCO3) is dissolved in water , the salt solution becomes : a) alkaline b) acidic c) neutral d) all of the above 5- The type of bond between water molecules and each other is : a) Ionic bond b) Covalent bond c) Metallic bond d) Hydrogen bond 1st Sec 10 Integrated Science  Lesson oneAquatic Ecosystem Homework 1. Water is an important medium for chemical reactions because of................. (its transparent color - its ability to dissolve compounds – it has no effect on compounds - its high density) 2. What states can water exist in on the surface of the Earth............ (solid only - liquid only - solid and liquid - solid, liquid, and gas) 3. Which of the following spheres distinguishes planet Earth from other planets in the solar system........... (atmospheric sphere - lithosphere - biosphere - hydrosphere) 4. Where is the largest proportion of saline water found on Earth?........... (freshwater lakes - oceans and seas - groundwater - atmosphere) 5. What happens when water moves from the environment into a living cell?................. (it dissolves in the cell - it carries the necessary materials for energy production - it evaporates immediately - it transforms into thermal energy) 6. Which of the following characteristics of water is not a result of its ability to form hydrogen bonds? (the high boiling point of pure water at 100 degrees Celsius - its ability to act as a solvent for polar substances - it has a neutral (pH) - both the first and second) 7. Which of the following represents the proportion of freshwater on the surface of the Earth?............ (97% - 70% - 3% - 50%) 8. What percentage of oceans, seas, saline lakes, and other saline water makes up the hydrosphere?........ (70% - 3% - 5% - 97%) 9. Transpiration in plants represents a type of process............ in the hydrological cycle. (evaporation process - filtration process - biological process - precipitation process) ‫ع‬ Integrated Science 11 1st Sec  Aquatic Ecosystem 10. The bond present between water molecules is.................... (ionic - single covalent - hydrogen - double covalent) 11. Which of the following salts, when dissolved in water, increases the concentration of hydrogen ions? (sodium carbonate - sodium chloride - ammonium chloride - potassium nitrate) 12. Groundwater that is exposed to calcium carbonate rocks is rich in........... (OH⁻ - H⁺ - H⁻ - OH⁺) 13. Groundwater exposed to magnesium carbonate rocks is........ (acidic - basic - neutral - other) 14. When sodium chloride is added to water, the resulting solution....... (turns red - turns blue - has no effect - none of the answers are correct) 15. The ratio of hydrogen ion concentration in freshwater to its concentration in rainwater is........ (less than - greater than - equal to - no correct answer) 16. If hydrogen bonds were absent from a water molecule, its boiling point compared to hydrogen sulfide would be........ (lower - higher - equal - cannot be determined) 17. Which of these samples always has a hydroxide ion concentration (-OH) greater than that of hydrogen ions (+H)............ (groundwater - Gulf of Aqaba water - Lake Nasser water - rainwater) 18. The highest pH value is found in................. (distilled water - water vapor containing carbon dioxide - water mixed with sodium chloride - seawater) 19. The hydrosphere refers to water in any state: (liquid - gas - solid - other) 20. Freshwater represents...... of the hydrosphere percentage: (70% - 5% - 3%) 1st Sec 12 Integrated Science