Thermal Chemistry Chapter 8 Heat and you

11.1 The Flow of Energy Law of Conservation of Energy: energy can neither be created nor destroyed, but can change forms. Energy is the capacity to do work or to supply heat Example: Energy needed to walk….where did this come from? Go “backwards” to determine the original source of energy

Endothermic and Exothermic processes Endothermic… absorb heat from the surrounding area(s)‏ Has a cooling effect on environment Exothermic… releases heat to the surrounding area(s)‏ System becomes cooler, environment becomes warmer

Car’s cooling system system.htmhttp://auto.howstuffworks.com/cooling- system.htm

Refrigerators Check it out!!! You’ll be able to find out why the back of your refrigerator is warm!

HEATHEATHEATHEATHEATHEATHEATHEAT

–V–Vibrational energy is transferred from one particle to the next »O»One particle collides with the next particle and so on; and so on – down the line An Ice Cold Spoon A Hot Spoon

11.2 Measuring and Expressing Heat Changes Thermo chemical equations show the accompanying heat of reactions at a constant pressure Calorimetry measures heat changes associated with chemical reactions and phase changes Heat Lost [q (lost) ] = -Heat Gained [ q (gained) ] = mass x specific heat x change in temp 50 grams of water is heated from 20 to 40 degrees Celsius, how much heat will it take in joules? C water =4.184 J/gr 0 C How much heat is needed to melt 580 grams of ice that starts at C ? C ice =.5 J/gr 0 C

Definitions Heat can be measured in Joules or calories. Specific heat-the heat necessary to raise one gram of any substance 1 degree celsius Joule= 1calorie =specific heat of water 1 calorie - the specific heat of pure water 1 dietary Calorie (written with a capital C) = 1000 calories. Refers to the amount of potential energy in food molecules.

Specific Heat Values of Metals ( Joules/gr 0 C)‏ MetalSpecific Heat Copper.386 Aluminum.900 Iron.452 Lead.128 Zinc.388 Tin.228 Air1.4 Water4.184

Specific heat of some common substances Substancecalories/(g x degrees Celsius)‏ water 1.00 alcohol0.58 ice0.5 wood0.42 steam0.4 chloroform0.23 aluminum0.21 glass0.12 iron0.11

Specific heat of some common substances Substancecalories/(g x degrees Celsius)‏ water 1.00 alcohol0.58 ice0.5 wood0.42 steam0.4 chloroform0.23 aluminum0.21 glass0.12 iron0.11

Calculating Specific Heat Heat Lost/Gained = (mass) (Specific Heat) (Change in Temp)‏ Joules = (grams) (Joules/gr- 0 C) ( 0 C)‏ For a metal dropped into water: Heat lost by metal = heat gained by water (mass) (Specific Heat) (Change in Temp)= (mass) (Specific Heat) (Change in Temp)‏ -Solve for Specific Heat of the metal as an unknown C metal = (mass water )(Sp. Heat water )(Change in Temp water )‏ (mass metal ) (Change in Temp metal )‏

Calorimetry

Food and Calories How many calories do you need? The Easy Way If all of those calculations seem too confusing or tedious, you can roughly estimate your daily calorie requirements using this simple formula: For sedentary people: Weight x 14 = estimated cal/day For moderately active people: Weight x 17 = estimated cal/day For active people: Weight x 20 = estimated cal/day 3500 calories = 1 lb. Fat storage

11.3 Heat in Changes of State The molar heat of fusion, solidification, and vaporization and condensation describe the quantity of heat transferred to or from a system when 1 mole of substance undergoes a change of state at a constant temp.

11.4 Calculating Heat Changes Hess’s Law: in a reaction that is the sum of two or more other reactions a change in heat for the overall process is the sum of the change of heat values for all of the parts of the reactions The heat of the reaction for the formation of 1 mole of a compound from its elements in standard states is the heat of the reaction of the formation H f o The standard heat of a reaction change for a reaction can be calculated from the H f o of the reactants and products

Calculating Specific Heat Heat Lost/Gained = (mass) (Specific Heat) (Change in Temp)‏ in other words Specific Heat = heat input / mass (g) * change in temperature (degrees Celsius)‏ joules or calories can be used.

Find the heat needed to increase the temperature of 5.6 grams of aluminum by 24 degrees Celsius. (refer to the chart on p. 296 of the textbook, “Specific Heat Capacities of Some Common Substances”). 0.9Joules/gr- o C (specific heat of aluminum)‏

Heat in time TempTemp ice water steam ice water steam 100C 0C Heating Curve for Water

Oranges…An Example! Farmers farm oranges in the winter oranges could FREEZE!!! To prevent this they pour water on the oranges and let the water freeze instead! (poor water) Freezing gives off a lot of heat. So when the water freezes it gives the heat to the oranges!! HOW NICE. Freezing is exothermic…so the orange absorbs the heat from the water as the freezing occurs.

Ocean Influence on Land Weather Why are weather conditions different for communities located near the ocean compared to those located more inland?

- How does the Ocean Affect the Weather?

- Water, gases, and energy are exchanged between the ocean and atmosphere - Moderates the surface temperatures of the ocean - Shapes the Earth’s weather and climate - Generates most of the ocean’s waves This Exchange:

-WEATHER is the state of the atmosphere at a specific place and time - CLIMATE is the long-term (30 year) average of weather in an area - Both weather and climate are affected by the ocean - Lets see some examples of how the ocean influences our weather

Ever Notice??? Our weather here is different than the weather inland? Ocean’s effect on local weather

WINTER Water is warmer than land during winter. The ocean warms the cities right along the coast

SUMMER Water is cooler than the land during summer. Now the oceans cools the coastal cities

Why is there almost always a breeze at the beach? - The land and water heat at different rates - Land heats and cools faster than the water

Cooler Ocean Warmer Land Warmer temperatures cause air to rise Onshore Breeze Cool air sinks to fill in the space Afternoon Breezes are onshore Clouds Form Afternoon Showers

Warmer Ocean Cooler Land Warmer temperatures cause air to rise Offshore Breeze Cool air sinks to fill in the space Evening Breezes are offshore

- Great masses of warm, humid, rotating air - Occur in tropical oceans -Called “Hurricanes” in the North Atlantic “Typhoons” in the Western Pacific “Cyclones” in the Indian Ocean “Wili-Wilis” near Australia

- Hurricanes start out as Tropical Depressions (Low Pressure Zones) off the coast of Africa or in the Caribbean - Next, when their wind speeds reach 40 mph they become Tropical Storms (and they get a name) ‏ - They become Hurricanes once they reach a wind speed of 74mph

Typical Hurricane Path is around the Atlantic’s high pressure cell Category One -- Winds miles per hour Category Two -- Winds miles per hour Category Three -- Winds miles per hour Category Four -- Winds miles per hour Category Five -- Winds greater than 155 miles per hour Saffir-Simpson Scale

Most hurricanes make landfall in the Southeast U.S. of Gulf States

Names for Atlantic Basin Tropical Cyclones 2002 Arthur Bertha Cristobal Dolly Edouard Fay Gustav Hanna Isidore Josephine Kyle Lili Marco Nana Omar Paloma Rene Sally Teddy Vicky Wilfred 2003 Ana Bill Claudette Danny Erika Fabian Grace Henri Isabel Juan Kate Larry Mindy Nicholas Odette Peter Rose Sam Teresa Victor Wanda 2004 Alex Bonnie Charley Danielle Earl Frances Gaston Hermine Ivan Jeanne Karl Lisa Matthew Nicole Otto Paula Richard Shary Tomas Virginie Walter 2005 Arlene Bret Cindy Dennis Emily Franklin Gert Harvey Irene Jose Katrina Lee Maria Nate Ophelia Philippe Rita Stan Tammy Vince Wilma 2006 Alberto Beryl Chris Debby Ernesto Florence Gordon Helene Isaac Joyce Kirk Leslie Michael Nadine Oscar Patty Rafael Sandy Tony Valerie William 2007 *Allison Barry Chantal Dean Erin Felix Gabrielle Humberto Iris Jerry Karen Lorenzo Michelle Noel Olga Pablo Rebekah Sebastien Tanya Van Wendy

A hurricane’s energy source is warm seawater (>80°F)‏