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Science of Mixtures in Everyday Consumables:
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In assessing the purity of consumables like milk, ghee, butter, salt, spices, mineral water, or juice, we often encounter the term ‘pure’ on their packaging, but scientifically nothing is pure rather it’s just a mixture. For instance, milk is a blend of water, fat, proteins, and more.
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Mixtures: Science behind Everyday Blends
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- Complexity of Multiple Substances: It consists of multiple types of pure substances, whereas pure substances, regardless of their source, exhibit consistent characteristic properties.
- Example: Sodium chloride and sugar cannot be separated by physical process into its chemical constituents but soft drink and soil being mixed can be separated into its constituents.
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What are the different types of Mixtures ?
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- Depending upon the nature of the components that form a mixture, we can have different types of them.
- Homogeneous: Uniform Blend of Components: It refers to a mixture in which the components mixed are uniformly distributed throughout (e.g., salt in water)..
- Example: Salt in water etc.
- Heterogeneous Mixtures: Microscopic Insights and Examples: This is a type in which all the components are completely mixed and all the particles can be seen under a microscope.
- Example: Mix of sodium chloride and iron filings etc.
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How do Solutions differ from other Mixtures?
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- Homogenous Mixture: Science of Solutions: A solution is homogeneous, consisting of two or more substances.
- Example: Lemonade and soda water.
- Solid and Gaseous Solutions: It is not just a liquid that contains either a solid, liquid or a gas dissolved in it, but we can also have solid solutions (alloys) and gaseous solutions (air).
- Homogeneous Solutions and their Balanced Distribution: Homogeneity exists at the particle level in a solution, meaning the components are evenly distributed.
- Example: Lemonade tastes the same throughout.
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Solution Composition: Roles of Solvent and Solute
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- A solution has a solvent and a solute as its component.
- Solvent: Usually present in larger quantities, is the component that dissolves the other substance.
- Solute: It usually present in lesser quantities, is the component that is dissolved in the solvent.
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Properties of a Solution: Small Particles, Light Paths and Filtration Dynamics
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- Smaller Size: It’s homogeneous, in which the particles are smaller in size (< 1 nm), making them invisible to naked eyes.
- Scattering: Because of the very small particle size, they do not scatter a beam of light passing through the solution, hence the path of light is not visible.
- Filtration: As the solute particles do not settle down when left undisturbed, they cannot be separated from the mix by the process of filtration.
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Examples of Solution: Sweet Sugars to Gaseous Mixtures in Everyday Life:
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- Sweet Solution: Sugar and Water Mix: It has sugar as the solute and water as the solvent.
- Iodine Infusion: Tincture of Iodine in Alcohol: It has iodine (solid) as the solute and alcohol (liquid) as the solvent.
- Gas-Liquid Solutions in Aerated Drinks: Drinks like soda water, etc, are gas in liquid solutions.
- These contain carbon dioxide (gas) as solute and water (liquid) as solvent.
- Composition of Air: It is a mixture of gas in gas, containing oxygen (21%) and nitrogen (78%) as major constituents.
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How does the concentration of a solution influence its properties, and what distinguishes a saturated from an unsaturated solution?
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- Varieties in Solution Strength: Different Concentrations: As the solution is made of solute and solvent, their proportions can be varied to get different concentrations of solutions.
- Understanding Concentration Formulas: The concentration of a solution is the amount (mass or volume) of solute present in a given amount (mass or volume) of solution.
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- Concentration of Solution = Amount of solute/Amount of Solution
- Saturated Solution: Deeper Look into Concentration: At any particular temperature, a solution that has dissolved as much solute as it is capable of dissolving, is said to be a saturated solution and the amount of the solute present in the saturated solution is called its solubility.
- Unsaturated Solution: Below Saturation Levels: If the amount of solute contained in a solution is less than the saturation level, it is called an unsaturated solution.
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Suspension: Visible Particles in Heterogeneous Mixtures
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- A suspension is an example of a heterogeneous mixture where solute particles do not dissolve but instead remain suspended evenly within the medium.
- Unlike solutions, particles in suspensions are visible to the naked eye.
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How do Suspensions exhibit Heterogeneity through Filtration and Scattering?
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- Heterogeneous Mixture: Visible Particles: It’s a heterogeneous mixture in which the particles of a suspension can be seen by the naked eye.
- Scattering in Particle-Rich Mixtures: The particles of a suspension scatter a beam of light passing through it, making its path visible.
- Filtration’s Role in Settling Solute Particles: As the solute particles settle down when left undisturbed, they can be separated from the mixture by the process of filtration.
- When the particles settle down, the suspension brakes and it does not scatter light any more.
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Colloidal Solution: Composition, Properties and Stability
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- Homogeneous Heterogeneity of Colloidal Mixtures: Colloidal solution is a heterogeneous mixture, consisting of smaller particles that are uniformly spread throughout the solution.
- Components of Colloidal Solutions: A colloidal solution consists of two main components, the dispersed phase (the solute-like component, comprising the dispersed particles) and the dispersion medium (the component in which the dispersed phase is suspended).
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Properties of a Colloid solutions
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- Small Size: Understanding Particle Size: It’s a heterogeneous mixture in which the size of particles is too small to be individually seen with naked eyes.
- Scattering: Light Play: Scattering in Colloids: Colloids are big enough to scatter a beam of light passing through it and make its path visible.
- Stability: Endurance of Colloids: They do not settle down when left undisturbed, that is, a colloid is quite stable.
- Filtration Challenges: Separating Colloids from the Mix: They cannot be separated from it by the process of filtration, but can be separated through centrifugation.
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