Exploring Physical Changes

Physical Changes

• Physical changes alter a substance's appearance or form without changing its chemical composition.
• These changes are typically reversible.

Change of State

• Matter transitions between solid, liquid, and gaseous states.
• Examples include melting (solid to liquid), evaporation (liquid to gas), and condensation (gas to liquid).
• Ice melting into water is a change of state, but it remains H2O.

Change of Form

• Modifying an object's shape without altering its chemical makeup.
• Examples: cutting, folding, or crushing.
• Tearing or folding paper changes its form but not its chemical composition.

Change of Size

• Increasing or decreasing a substance’s size.
• Example: metal expanding when heated or compressing an object.
• An inflated balloon expands as more air is added.

Mixtures

• Combining two or more substances without creating new substances.
• Components can be separated through physical methods like filtration, distillation, or decantation.
• Mixing sand and water or dissolving salt in water forms a mixture, but the substances retain their chemical identities.
• Physical changes generally don't involve underlying chemical transformations.
• They tend to be reversible.

Dilution

• Dilution reduces the concentration of a solution by mixing it with a solvent, usually water.
• It dilutes a more concentrated solution.

Dilution Formula

• The formula relies on the principle of solute quantity conservation.
• C1 x V1=C2 x V2, where:
  • C1 = initial concentration.
  • V1 = initial volume.
  • C2 = final concentration.
  • V2 = final volume.
• C1 × V1 represents the solute amount in the initial solution.
• C2 × V2 represents the solute amount after dilution.
• Solute quantity remains constant, but concentration changes due to the solvent.

Determining Final Volume (V2)

• V2 = (C1 × V1) / C2

Determining Final Concentration (C2)

• C2 = (C1 × V1) / V2

Dilution Example

• A solution with a concentration of 10 mol/L.
• Take 100 mL of the solution and dilute it to a final volume of 500 mL.
• Applying the formula: C2 = (10 mol/L × 100 mL) / 500 mL = 2 mol/L.
• The final concentration is 2 mol/L.

Conclusion

• Dilution relies on adding a solvent to reduce a solution's concentration.
• You can use the dilution formula to determine final concentration or volume.

Chemical Transformations in the Human Body

• Chemical transformations facilitate key biological processes in the body.

Digestion

• Involves breaking down complex food molecules into simpler ones using enzymes.
• Proteins are broken down into acids via enzymes such as pepsine in the stomach.

Cellular Respiration

• The conversion of glucose into energy.
• Cells use glucose (C₆H₁₂O₆) and oxygen (O₂) to produce energy (ATP), carbon dioxide (CO₂), and water (H₂O).
• C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP)

Protein Synthesis

• Proteins are manufactured in ribosomes.
• Amino acids are linked by peptide bonds to form proteins.

Fat Breakdown (Lipolysis)

• Triglycerides break down into fatty acids and glycerol.
• Triglycerides in fat cells are broken down by enzymes like lipase.

Urine Production (Renal Filtration)

• Filtration of waste products in the kidneys.
• Kidneys filter blood to eliminate waste, regulating water and electrolyte balance.

Photosynthesis

• Conversion of light into chemical energy; primarily in plants.
• Photosynthesis converts water (H₂O) and carbon dioxide (CO₂) into glucose (C₆H₁₂O₆) and oxygen (O₂).

Fermentation

• The production of energy without oxygen.
• Glucose is transformed into lactic acid and energy in muscles lacking oxygen.
• C₆H₁₂O₆ → 2C₃H₆O₃ + energy

Detox Reactions

• Detoxifying harmful chemicals.
• The liver breaks down toxic substances, such as medications and alcohol.

Oxidation Reactions

• Process where a substance loses electrons.

Oxidation of Iron (Rust)

• 4Fe + 3O₂ → 2Fe₂O₃
• Iron atoms lose electrons, reacting with oxygen (O₂) in the air.
• Iron atoms lose electrons (oxidized) and form Fe²⁺ or Fe³⁺ ions.

Oxidation of Magnesium

• 2Mg + O₂ → 2MgO
• Magnesium atoms lose two electrons to form Mg²⁺ ions.
• Each magnesium atom loses two electrons, forming Mg²⁺ ions.

Oxidation of Hydrogen (Water Formation)

• 2H₂ + O₂ → 2H₂O
• Hydrogen molecules react with airborne oxygen.
• Each hydrogen atom (H) loses an electron, becoming an H⁺ ion.

Oxidation of Glucose

• C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP)
• Glucose reacts with oxygen to produce carbon dioxide, water, and energy.
• Glucose is oxidized, and carbon atoms in glucose lose electrons to produce ions of CO₂.

Oxidation of Ethanol

• C₂H₅OH + O₂ → CH₃COOH + H₂O Ethanol reacts with oxygen (O₂) in the liver to form acetic acid and water.
• Ethanol loses electrons and transforms to acetaldehyde, then into acidic acid.