PPT CHEM WATER

• Water has various distinctive properties that are fundamental to life.

  The astonishing properties of water are acquired from

  its molecular structure and the interaction among

  individual molecules.
• H2O is the chemical formula of water, its bond is covalent in nature with a bent molecular geometry.

  The water molecule is made up of two hydrogen atoms bonded to an oxygen atom.
• There are few special characteristics of water which includes

  • tendency to form hydrogen bonds
  • its polar character
  • capability to hydrate metal ions
• HYDROGEN BONDS

  • Hydrogen bonds are a type of intermolecular force that occurs between molecules.
  • In water, hydrogen bonds form between the hydrogen atom in one water molecule and the oxygen atom in another water molecule. Oxygen has a partial negative charge and hydrogen has a partial positive charge.
• HYDROGEN BONDS

  Hydrogen bonds are electrostatic attractions between a hydrogen atom (bonded to an electronegative atom) and a neighboring oxygen, nitrogen, or fluorine atom.

  • Example: Ammonia (NH₃)
• HYDROGEN BONDS

  • Atoms involved in hydrogen bonds are farther apart than in covalent bonds, allowing for flexibility in molecular interactions.
  • Covalent has a much stronger bonds which connects atoms within molecules.
• POLAR CHARACTERISTIC OF WATER

  • Water (H₂O) is a polar molecule due to the unequal sharing of electrons between oxygen and hydrogen atoms.
  • Oxygen is more electronegative than hydrogen, creating a partial negative charge on the oxygen and partial positive charges on the hydrogens.
• • This difference in charge distribution creates a dipole, where one end of the molecule is slightly negative, and the other is slightly positive.
  • The three atoms in water molecule (H-O-H) are not in a straight line; instead, they form an angle of 104.5°
• The bent structure of water molecule is due to fact that there is a stronger attraction between oxygen and the negative electron than with the hydrogen atoms and also the water molecule acts like a dipole having opposite electrical charges at either end. 
• Water’s polar nature enables it to surround charged ions. For example, when sodium chloride (NaCl) dissolves, Na⁺ ions are surrounded by water’s negative (oxygen) ends and Cl⁻ ions are surrounded by water’s positive (hydrogen) ends.
• CAPABILITY TO HYDRATE METAL IONS 

  • When metal ions dissolve in water, they undergo hydration, where water molecules surround and stabilize these ions.
  • The hydration ability of water is why it can dissolve many ionic compounds and salts that other solvents cannot.
• More Properties of Water

  
• More Properties of Water

  
• More Properties of Water

  
• CLASSIFICATION OF WATER BY SOURCE

  • Potable water- is safe for drinking, cooking, bathing and washing dishes. 
  • In contrast, non-potable water is contaminated with pollutants that include particulates from dirt and toxic metals (e.g. arsenic), or bacteria that cause cholera.
• Surface water- most convenient source for human activities. It can be found in lakes, rivers, and streams.
• Groundwater- less convenient to access. It is the fresh water found in underground reservoirs also known as aquifers. People worldwide pump groundwater from wells drilled deep into these underground reservoirs. Fresh water is also found in our atmosphere in the form of mists, fogs, and humidity
• General Characteristics of Groundwater and Surface Water

  
• Ground and Surface Water

  
• HYDROLOGICAL CYCLE

  • The hydrological cycle includes all the water present on and in the Earth, including salt and fresh water, surface and groundwater, water in the clouds, and water trapped in rocks below the Earth’s surface.
  • Describes the movement and conservation of water on Earth.
• Two distinct processes for the transfer of water to the earth’s atmosphere:

  • Evaporation: The conversion of liquid water from bodies like lakes, streams, and other water sources into water vapor.
  • Transpiration: The process by which water is emitted from plants through stomata.
• Water Movement After Precipitation:

  • Surface Runoff: Water that flows over the ground into streams and rivers (also called overland flow or direct runoff).
• Water Movement After Precipitation:

  • Interflow: Water that moves laterally just below the ground surface.
  • Infiltration/Percolation: Water that moves vertically through the soil to form groundwater.
• Thermal Stratification of Water

  • The separation of these layers prevents them from mixing, leading to independent chemical and biological properties.
  • Water’s temperature-density relationship causes distinct layers to form in nonflowing bodies of water.
• • Epilimnion: The surface layer heated by solar radiation, which has lower density and floats on the layer below.
• Hypolimnion: The bottom layer that remains cooler and denser.
• • Thermocline (Metalimnion): The shear-plane or layer between the epilimnion and hypolimnion where the temperature shifts sharply.
• Solvent

  A substance often a liquid that is capable of dissolving one or more pure substances.
• Solute

  A solid, liquid or gas that dissolves in a solvent.
• Solution

  A homogeneous (of uniform composition) mixture of a solvent and one or more solutes.
• Aqueous solution

  A solution in which water is the solvent.
• Concentration

  It is the ratio of the amount of solute to the amount of solution.
• In case of many substances dissolved in drinking water that has a very low concentration, parts per million (ppm) is more commonly used.

  Some contaminants are of concern at concentrations much lower than parts per million, and are reported as parts per billion (ppb). In aqueous solutions, 1 ppb = 1 μg/L.

  One contaminant found in the range of parts per billion is mercury.
• One ppm of any substance in water is equivalent to 1 mg of that substance dissolved in a liter of solution (1 ppm = 1 mg/L).
• One part per billion of mercury (Hg) in water is equivalent to 1 gram of Hg dissolved in 1 billion grams of water. In more convenient terms, this means 1 microgram (1 μg or 1 × 10–6 g) of Hg dissolved in 1 liter of water. The acceptable limit for mercury in drinking water is 2 ppb:
• Molarity (M)

  It is defined as a concentration unit expressed by the number of moles of solute present in 1 liter of solution.

  
• The term specifies the grams of substance per 100 g of solution or suspension and is mathematically expressed as

  
• Acid (at a molecular level) is a compound that releases hydrogen ions(+), in aqueous solution.
• A hydrogen atom is electrically neutral and consists of one electron and one proton.

  If the electron is lost, the atom becomes a positively charged ion, H+.

  Because only a proton remains, sometimes H+ is referred to as a proton.
• HCl dissociates into H+ and Cl+. No HCl molecules remain in solution because they dissociate  completely in water, which is referred to as a strong acid.