Mixtures, Solutions & Chemical Processes
All matter can be broken down into two categories viz. pure substances and mixtures
- A pure substance is any matter that always has the same composition or “make up”.
- There are 2 classifications of pure substances: elements and compounds.
- An element is a substance that cannot be broken down into simpler substances. An element is made up of only one type of atom.
- A compound is a substance that is made up of 2 or simpler substances.
- A mixture is a combination of 2 or more substances “non-chemically”.
- This means we can separate a mixture without undergoing a chemical reaction or chemical change.
- All mixtures can be classified into 2 groups: homogeneous and heterogeneous.
- Homogeneous Mixture → (Solvent + Solute) not distinguished. for ex. solution & colloids
- Heterogeneous Mixture → (Solvent + Solute) readily distinguished. for ex. suspension mixture
Separation Methods of Mixtures
|For 2 Solids
||For 2 Liquids
|For Solids & Liquids||
Difference between Mixture & Compound
Solution, Suspension & Colloids
- Homogeneous mixture with particle size < 1 nm diameter
- Does not separate out on keeping still & cannot be separated by filtration
- Does not scatter light due to extremely small particles
- Examples include: Carbonated drinks, Salt & Sugar solution
- Heterogeneous but appears homogeneous with particle size b/w 1 – 100 nm in diameter
- Does not separate out on keeping still
- Separates out on centrifugation, not by filtration
- Scatters a beam of light – Tyndall Effect
- include Milk, Blood, Soap solution, Ink, Jelly, Starch solutions, Body lotions, Foam, Gels, Gemstones etc.
- Heterogeneous mixture with particle size > 100 nm in diameter
- Particles settle down on keeping still & separates out by filtration
- Scatters a beam of light with particles of the solute seen easily.
- Examples include: Sand in water, Milk of magnesia, Chalk solution in water
- Maximum quantity of solute in 100 gm of solvent at a particular temperature
- Increases on increasing the temperature in liquids ( Decreases in case of gas)
- No effect of pressure in liquids (solubility increases in case of gases on increasing pressure)
- Saturated Solution → No more solute can be dissolved without increasing temperature
- Unsaturated Solution → More solute can be dissolved without increasing temperature
Important Chemical Processes
- Spreading & mixing of one substance with the another due to the motion of particles, which continues till a uniform mixture is formed
- Mixing particles move in zigzag known as Brownian motion
- Increases with temperature, fastest in gases & slowest in solids
- Few of the examples are : Dust particles in air, Smell of perfume in air, Spread of virus on sneezing, CO2 & O2 in water, Leakage of LPG (Identified by ethyl merceptane – a strong smelling substance)
- Diffusion is the case of using semi permeable membrane b/w 2 mixtures
- Only solvent is allowed to pass, from higher solvent conc. to the lower
- Few of the examples are:
- Preserving of pickle in salt
- Swelling up of raisins in water
- Earthworm dying when come in contact with salt
- Same as osmosis but for transplantation of kidney in humans
- Passes solvent & blocks waste
- To change the state of a substance from one to heat energy is required.
- Latent heat does not increase temp. of a substance but is used in overcoming force of attraction b/w particle of a substance
It’s due to loss of latent heat that ice at 0*C is more effective in cooling than water at 0*C & due to gain of latent heat that steam at 100*C causes more severe burns than water at 100*C
- Transition of liquid to vapour at normal temperature
- Causes cooling when liquid evaporate as it draws latent heat of vaporisation from the liquid
- For ex. evaporation of ether or spirit from our hand, sweating, water kept in earthen pot
- Increases with temp, large surface area, wind speed & low humidity
- Transition of solids directly into gases without going through liquid state
- Ex: Dry ice, Camphor, Ammonium chloride, Iodine, Naphthalene, Anthracene