(also known as _________) Internal Energy (also known as _________)

B. Temperature change and its affect on matter Heat is _______, so when it is added to or removed from a substance, the mass of that substance _________ change 2. When objects are heated, they ________ 3. When objects are cooled, they__________

Conversions between scales: (cont.) Celsius Kelvin Examples: 200 oC = ? K 400 K = ? oC -30 oC = ? K 100 K = ? oC

Phase Change Graphs: ______________ Curve 20 40 60 80 1 2 3 4 5 6 7 8 20 40 60 80 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Temp(C) Time (min)

Phase Change Graphs: ________________ Curve

The ___ of the molecules in the substance changes 1. Melting and Freezing The temperature of most materials remains constant during melting or freezing (______ ________________________) When a substance melts, it must ______ energy when a substance freezes, it must ______ energy But wait: If the Avg. KE remains constant, where does the energy go or come from when the object is melting or freezing? The ___ of the molecules in the substance changes

Melting and Freezing (cont.) HEAT OF FUSION: Amount of heat needed to _____ 1 gram of a particular substance or the amount of heat ___ when 1 gram of a substance _________. q = m = Hf =

Heat of Fusion Examples: 1) How much heat is needed to melt 200 g of ice? 2) If 50,100 J of heat is released when a sample of water is frozen, how much water was in the sample?

Melting and Freezing (cont.) Factors affecting melting/freezing points 1. A ___________ dissolved in a liquid _______ its freezing/melting point. Salt “melts” ice by _________ its freezing temperature. Antifreeze _______ water from freezing

Melting and Freezing (cont.) 2. ____________________ The _________ of a skate blade on the ice melts the ice directly beneath it. The ice refreezes after the blade is removed. Applying pressure on the surface of ice ________ the melting point of the ice

2. Boiling (or Vaporizing) and Condensing The temperature of most materials remains constant during boiling or condensing (avg. KE remains constant) When a substance __________, it must ______ energy; when a substance ___________, it must ________ energy. While a substance boils or condenses, there is a change in the _______ of the molecules

Boling and Condensing (cont.) HEAT OF VAPORIZATION: Amount of heat needed to ________ 1 gram of a particular substance or the amount of heat ____ when 1 gram of a substance __________. q = m = Hv =

Heat of Vaporization Examples: 1) How much heat is released when 400 g of steam condenses? 2) If 565,000 J of heat is absorbed when a sample of water is vaporized, how much water was in the sample?

Boling and Condensing (cont.) Factors affecting boiling/condensation points 1. A substance dissolved in a liquid ___________ its boiling/condensation point. Antifreeze not only prevents __________ but also prevents water in the cooling system from ______________ away.

Boling and Condensing (cont.) 2. Pressure _________ the pressure on a liquid _________ the boiling point of that liquid Example: Pressure cooker We say that water boils at 100 oC (32 oF, 373 K). This (and other temp’s on a reference chart) is known as the _____________ boiling point. The normal boiling point occurs at ______________ (101.3 kPa, 1 atm, 760 mmHg, or sea level pressure)

Boling and Condensing (cont.) Technically water (or other liquids) can boil at __ ___________. Boiling occurs when the pressure of the vapor of the substance is _____________ atmospheric (air) pressure. See Table H in the Chemistry Reference Tables. Examples: 1) What is the normal boiling point of propanone? 2) At what pressure will water boil at 70 oC 3) At a pressure of 80 kPa, ethanoic acid boils at

3. Evaporation: Process where the __________ moving (more ___) molecules at a liquid’s surface ______ into the gas phase. When this happens, the temperature of the substance ____________. Perspiration Examples: Dog panting

C. Specific Heat Capacity (or Heat Capacity) The amount of heat needed to raise __ gram of a substance ___ ( or how much needs to be _____ to _____ the temperature ______) 40oC Amount of heat equal to specific heat added to substance **The ________ is defined by how much heat is needed to raise the temperature of 1g of _____ 1oC

Specific heat capacities of some substances: Phase J/g oC Ammonia liquid 2.43 Aluminum solid 0.90 Copper 0.39 Iron 0.45 Lead 0.13 Titanium 0.52 ice 2.05 water 4.19 steam gas 2.01

Understanding Specific Heat Capacity Assuming that each of the following substances have equal masses, start at the same temperature, and have the same amount of heat added to them: Iron, copper, aluminum, lead 1. Which substance will heat up the quickest? 2. Which substance will heat up the slowest? 3. Which substance will cool off the quickest?

C = specific heat capacity (in J/g oC or cal/g oC) The heat added to (or removed from) a substance can be found by the following formula: Q = heat (in J or cal) m = mass (in g) C = specific heat capacity (in J/g oC or cal/g oC) DT = temperature change (in oC or K)

Sample questions How much heat is needed to raise the temperature of 100 g of iron from 20 oC to 40 oC? If 3150 J of heat is added to 50g of an unknown substance to raise its temperature from 10 oC to 80 oC, what is the substance?

D. Conservation of Energy Neglecting heat energy lost to the surroundings, when 2 objects/ substances at ___________ temperatures are brought into contact, the heat energy lost by the _______ object/ substance is _________ by the _______ object/ substance.

Sample Problems 1a. When a 1000 g piece of iron is placed in 500g of 20 oC water, the water’s temperature rises to 25 oC. How much heat is gained by the water? 1b. What is the temperature change of the iron?

E. Calorimetry Every substance has a ________ set of characteristics that can help us identify it. One of those characteristics is a substance’s ____________________. If we can determine how much heat an unknown substance absorbs, we can identify it by looking up its _______ _______

A calorimeter is a device that allows us to measure the heat exchange between 2 substances. thermometer Insulated calorimeter cup Unknown object water

Sample Problem An unknown metal with a mass of 500 g is heated to 100 oC and then is placed in 500 g of water at a temperature of 20oC. If the final temperature of the water is 27.8 oC, what is the identity of the metal?

III Laws of Thermodynamics 1. First Law Whenever heat is added to a system, it transforms to an _______ amount of some other form(s) of __________ OR Heat Added = increase in + Work done internal energy by system

2. Second Law of Thermodynamics An object or system will naturally proceed from a state of _____________ (will break down, become unorganized). Disorder is also known as __________________

Entropy (cont.) To make a system more ordered, energy or work must be ____________into the system. ___________ Entropy ____________ _____________ to order system

Entropy (cont.) Entropy and Phases of Matter Solid Liquid Gas Increasing Entropy Decreasing Entropy 3. Third Law It is impossible to reach the temperature of absolute zero (0 K)