7 Energy (heat) measure in Joules, BTUs (British Thermal Units) calories and Calories. 1 calories = Joules1 BTU = 252 calories1 Calorie = 1000 calories
8 States of Matter Also called Phases of Matter Solids Liquids Vapors (gases)
9 Solids Have a definite shape Have a definite volume Particles VIBRATE in place
10 Liquids Have NO definite shape Have definite volume particles SLIDE freely
11 Gases (vapor) Have NO definite shape Have NO definite volume particles fill the volume of the container
12 Solids, Liquids & GasesSolids = can form crystals = solid where the particle are arranged into repeating patterns.Liquids = physical property of Viscosity = “thickness” – the resistance to flow.Gases = volume of gases depend greatly on pressure and temperature.
14 Melting the process of changing from a solid to a liquid energy is being put into the substancemelting point = the temperature at which melting occurs – physical propertythe melting point of water is 0ºC
15 Freezing the process of changing from a liquid to a solid energy is being pulled out of the substancefreezing point = same temperature as the melting point(used mainly in weather)
16 Vaporization the process of changing from a liquid to a gas energy in being put into the substanceevaporationboiling
17 Evaporationvaporization that occurs at the surface of the liquid
18 Boiling vaporization that occurs throughout the liquid boiling point = the temperature at which boiling occursthe boiling point of water is 100ºC
19 Condensation the process of changing from a gas to a liquid energy is being pulled out of the substance
20 Sublimation the process of changing from a solid to a gas energy is being put into the substanceex: dry ice (CO2)
21 Heating of water heat of vaporization heat of fusion STEAM 100°C WATER (liquid)heat of vaporization0°CICEheat of fusion
23 Conduction transfer of heat by direct contact (molecule to molecule) metals are good conductorspoor conductors = insulators
24 Convectiontransfer of heat by “convection currents” warm fluids are less dense than colder fluid thus warm fluids rise and cold fall.not possible in solidsfluid = anything that flows (liquids & gases)hot air balloons, “convection” ovens
25 Radiation transfer of heat by electromagnetic waves some wavelengths of infrared & ultravioletonly type of transfer that can occur through empty spacesun Earth
26 Specific HeatThe amount of heat needed to raise the temperature of one gram of a substance one degree Celsius.
27 Factors in Specific Heat types of substance (C)mass of the substance (m)how much of a temperature change (∆T)C = specific heat constantm = mass∆T = difference in the temperature
28 Specific Heat Calculations ∆Q = amount of heat absorbed (difference in the heat or heat change)∆Q = m x ∆T x CThe specific heat of water= 1.0 cal/g°C or= 4.2 joules/ g°C
29 EXAMPLE #1: How many calories are absorbed by a pot of water with a mass of 500 grams in order to raise the temperature from 20°C to 30°C?C = 1.0 cal/g°Cm = 500 grams∆T = 10°C (30-20)∆Q = m x ∆T x C∆Q = (500 g)(10°C)(1.0 cal/g°C)∆Q = 5000 calories
30 EXAMPLE #2: How many joules are absorbed by a pot of water with a mass of 500 grams in order to raise the temperature from 20°C to 30°C?∆Q = m x ∆T x C∆Q = (500 g)(10°C)(4.2 J/g°C)∆Q = 21,000 JoulesC = 4.2 J/g°Cm = 500 grams∆T = 10°C (30-20)
31 Phase Changes Heat of fusion (Hf) the heat energy needed to melt (or freeze) a substance.All heat being put into the substance goes to the melting processthus the temperature does not change while the substance is melting.
32 Phase Changes Heat of vaporization (Hv) the heat energy needed to boil (or condense) a substance.All heat being put into the substance goes to the boiling processthus the temperature does not change while the substance is boiling.
33 Heat & Phase Changes Hf = mass x Hf constant The heat of fusion of water = 340 J/gHv = mass x Hv constantThe heat of vaporization of water = 2300 J/g
34 EXAMPLE: How many joules of heat are necessary to melt 500 g of ice? Chf = 340 J/gm = 500 gH = Chf x mH = (340 J/g)(500 g)H = 170,000 J