Water for Food Chemistry for BSc students

Water for Food Chemistry for BSc students

1. Unit - I Chemistry of d-Block Elements B.Sc. Semester – I Inorganic Chemistry Presentation by Dr. Nandan C. Pomal Assistant Professor, Faculty of Science, Sigma University, Vadodara, Gujarat, India

2. Course Content Water as universal solvent & chemical bonding Water: Physical properties of water, Structure of water molecules, bound water, free water Chemical bond, Octet rule, ionic bond, covalent bond, polar and non-polar bond, hydrogen bond

3. Water – A Universal Solvent Water, often termed the "universal solvent," possesses a unique ability to dissolve a wide range of substances. This exceptional property is due to its molecular structure.

4. Water molecules have a bent shape with an oxygen atom at one end and two hydrogen atoms at the other. The oxygen atom is slightly negative, while the hydrogen atoms are slightly positive. This polarity creates a strong attraction to other polar molecules and ions. Why is Water such a Good Solvent? Due to polarity of water molecules they form hydrogen bonds with each other and with other molecules, therefore it enhance its ability to dissolve substances. Hydrogen bonding Polarity

5. Water's role as a solvent is vital in countless processes: Biological systems: Water transports nutrients and oxygen throughout living organisms, removes waste products, and regulates body temperature. Environmental systems: Water plays a crucial role in weathering and erosion, carrying dissolved minerals and sediments. Industrial processes: Many industrial processes rely on water as a solvent, including chemical reactions, cleaning, and purification. Importance of Water as a Solvent While water is an excellent solvent for many substances, it does have its limitations. For example, it cannot dissolve nonpolar substances like oils and fats. Limitations of Water as a Solvent Why is Water such a Good Solvent?

6. Chemical Bonding in Water 1. Covalent bonding: Two hydrogen atoms share their electrons with a central oxygen atom. This sharing forms a strong bond between the atoms. 2. Hydrogen bonding: The polar covalent bonds in water create a partially positive hydrogen end and a partially negative oxygen end. Hydrogen atoms from one water molecule can then attract the oxygen end of another water molecule. These hydrogen bonds are weaker than covalent bonds but are crucial for water's properties. Thus, role of covalent bond is to hold the atoms within a water molecule together, while hydrogen bond allows water molecules to interact with each other. These interactions between water molecules are responsible for many of water's unique properties, such as its high surface tension and its ability to act as a universal solvent.

7. Physical Properties of Water State of Matter: Exists in all three states of matter: Solid (ice), liquid (water), and gas (water vapor). Unique property: Ice is less dense than liquid water, causing it to float. Color, Odor, and Taste: Pure water is colorless, odorless, and tasteless. Boiling Point and Melting Point: Relatively high boiling point (100°C) and melting point (0°C) compared to other compounds of similar molecular weight, this is due to strong hydrogen bonding between molecules. Density: Maximum density at 4°C. Density decreases below and above this temperature. Surface Tension: High surface tension due to strong cohesive forces between water molecules.

8. Capillary Action: Ability to rise in narrow tubes against the force of gravity. Important for plant water transport. Solvent Properties: Excellent solvent for many substances due to its polar nature. Often referred to as the "universal solvent." Viscosity: Low viscosity compared to other liquids, allowing for easy flow. Specific Heat Capacity: High specific heat capacity, meaning it takes a significant amount of energy to change its temperature. This property is crucial for temperature regulation. Heat of Vaporization: High heat of vaporization, requiring a large amount of energy to convert liquid water to vapor. This property is essential for cooling processes. Physical Properties of Water

9. Most natural foods contain water up to 70% of their weight or greater unless they are dehydrated, and fruits and vegetables contain water up to 95% or greater. Free Water: Water that can be extracted easily from foods by squeezing or cutting or pressing is known as free water. Bound Water: Water that cannot be extracted easily is termed as bound water. Free Water and Bound Water

10. Contributes to food juiciness Ex. fresh fruits Influences food flavor Ex. water-soluble compounds. Affects food safety Ex. microbial growth. Free Water and Its Characteristics It can be easily be removed by squeezing or drying. It behaves like typical water. It acts as a solvent for solutes. Supports microbial growth. Characteristics Impact on food

11. Some characteristics of bound water include; It is not free to act as a solvent for salts and sugars. It can be frozen only at very low temperatures (below freezing point of water). It exhibits essentially no vapor pressure. Its density is greater than that of free water. Bound Water and Its Characteristics Characteristics Contributes to food texture Ex. chewy bread. Influences food stability Ex. prevents spoilage. Affects food processing Ex. dehydration. Impact on food