Unit 3 chemistry

Phase change Terminology

Melting: From a solid to a liquid ; heat is added

Solidification: From a liquid to a solid; heat is removed; also called fusion

Sublimation: From a solid to a Gas

Depositions: Gas to Solid phase change

Evaporation: Liquid to gas; heat added

Definite shape, Definite Volume, Highly Organized

Energy

Definition:

Intermolecular Forces (IMF's)

Specific heat capacity

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They're Forces that act between stable molecules

Solid: Strong IMF, so low entropy

Liquid: Moderate IMF, so moderate entropy

Gas: Low IMF, so high Entropy

Thermal energy

equation Q=mc^t

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Q: heat energy (Joules or calories)

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M: mass (g)

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C: Specific heat capacity

How mush energy it takes to heat up one gram of a substance by one degree Celsius

Specific heat: The higher the specific heat, the more energy is needed to heat up the substance/ Lower the specific heat= the less energy is needed

^t: Change in Temperature (Celsius)

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Difference between Temperature and heat

Temperature: Average Kinetic energy of particles in a substance

Hotter substances having faster moving particles

Units for temperature: Celsius does not work for gas laws so Kelvins should be used K= Celsius + 273

Matter

Liquid

Indefinite Shape, Definite Volume, Less Organized

Solid

Gas

Indefinite Shape, Indefinite Volume, Very Disorganized

Plasma

A Gas heated up so intensely that the electrons break away from their distinct atoms

In order from Solids to a Gas is the Increase in Entropy and Kinetic Energy

Entropy: How much "Chaos" in the molecules of a substance

Units of Pressure

Atmospheres (ATM): Normal atmospheric pressure is one atm

KiloPascals (kPa): The normal atmospheric pressure for this is 101.325 kPa

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Volume

Definition: the amount of space a gas takes up; measured in Liters (L) for gases; possibly measured in mL; 1L=1000 mL

Assumptions made for ideal gases

Particles have no volume

Particles have no intermolecular forces

Particles are in constant motion and travel randomly in straight lines, bouncing off one another

Gas laws

Boyles Law: As pressure increases, volume decreases; P1 V1= P2V2

Charle's Law: As gas temperature increases, Volume increases; equation is V1/T1= V2/T2

Combined gas law: It is a combination of Boyle's and Charles' law, where one of the values does not always have to e constant, so you may use any variables

Dalton's Laws of partial pressure: If you have a mixture of gases, the total pressure is the sum is all the pressures of each gas; P total= (P1+P2+........)

phase Diagram:

Critical pressure: occurs at 218 atm in water

Normal freezing point: 32 degrees fahrenheit or 273.15 Kelvin

Triple point: It is that temperature and pressure at which the sublimation curve, fusion curve and the vaporization curve meet. or the temperature and pressure at which the solid, liquid, and vapor phases of a pure substance can coexist in equilibrium.

Normal boiling point: It's the temperature at which a liquid boils at 1 atmosphere of pressure.

Critical point: the point on the phase diagram at which both the liquid and gas phases of a substance have the same density, which means they are indistinguishable.

Ideal gas law; PV=nRT

Pressure (atm or kPa)

Volume: (L or mL)

Number of Moles of the gas (mol or Mole)

R: Gas constant

Temperature (k)