Explore & Learn

• Convection is the process of heat transfer through a fluid (liquid or gas) by the movement of the fluid itself.

Convection Current

• Convection current is when the particle from a hotter temperature move to a cold temperature

• Example - a pot of soup heating on the stovetop from a conductor

2 Types Of Convection

• Natural Convection

• Forced Convection

Natural Convection

• Occurs due to natural differences in temperature.

• Warm fluid becomes less dense and rises; cooler fluid is denser and sinks.

Forced Convection

• External force like a fan moves the fluid.

Convection And Conduction Difference

• In convection, energy is transferred through a material from a warmer place to a cooler place by the movement of the material itself.

• In conduction, energy is transferred through a material from a warmer place to a cooler place without the material itself moving.

Conductor

• Conductor is the material that allows free flow of electrons

• Conductor can also allow the free flow of heat

• Conductor works as atoms with valency shell have electrons that are attracted to the nucleus but compared to the first shell their attraction will be lower thus when they have higher energy from light or temperature they tend to escape

• Example - Metal

Insulator

• An insulator is a material that does not allow electric current or heat to flow easily through it.

• A insulator does not allow the flow of electrons as their electromagnetic force will be high and hard to break the force

• Example -: Wood

• When one side of metal is heated, their electrons share the energy, this makes the other electrons vibrate

• These kind of electrons are called delocalized electrons

• A theory that argues population growth will outpace the growth of food production

Malthusian Trap

• Surplus → Population growth → Resource strain → Crisis → Decline

  • From a surplus in exports

  • There will be population growth as exports lead to economic birth and possible reports have shown that economic growth can happen when exports increase

  • Resources become finite

  • This can lead to economic decline as deficit increases

• Method To Prevent Malthusian Trap ( Historic Method )

  • These increase death rates:

    • Famine

    • Disease

    • War

    • Natural disasters

  
  

• Climate Malthusianism

  • Overpopulation → carbon emissions → climate collapse.

  • Planetary boundaries, ecological footprints, water scarcity

• Malthus In Modern Economics

  • Development economics: Why some nations remain poor.

  • Environmental economics: Carrying capacity, sustainability.

  • Growth theory: Pre-Industrial stagnation was Malthusian; post-Industrial was the escape.

Mass And Molar Concentration

• Molar concentration (also called molarity) is the number of moles of solute (the substance being dissolved) per litre (dm³) of solution.

• Basically molar concentration is the concentration of the number of moles

Example - 1

You dissolve 0.5 moles of NaCl in 1.0 dm³ of water. What is the molar concentration?

Standard Solution

• A solution whose concentration is known precisely

Titration

• A method of quantitative analysis using solutions

Example -2

25.0 cm³ of HCl is neutralized by 20.0 cm³ of NaOH of concentration 0.100 mol/dm³. What is the concentration of HCl?

• “Equal volumes of gases, under the same conditions of temperature and pressure, contain the same number of particles.”

• If the temperature and pressure be the same, their volumes shall contain an equal number of molecules.

• Even if the number of molecules remains constant, the mass of a substance can change through a change in state (solid, liquid, gas) or through chemical reactions.

The Formula of moles and volume

Volume

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No. of moles | Molar volume

• The formula of moles and volume talk about the ratio of the volume and the number of moles in volume per unit

• Avogadro’s law – Same volume → Same number of particles (at same temp and pressure)

• r.t.p. – Room Temperature and Pressure: 25°C (298K), 101.3 kPa (1 atm)

• Molar gas volume – 1 mole of any gas = 24 dm³ at r.t.p.

• For gaseous reactions, the volume ratios are the same as mole ratios