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Chapter 17 pgs. 505- 533
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q= m x c x T This is the equation for all Thermochemistry problems The Q is heat values in either calories or joules (4.18 joules = 1 calorie) The m is the mass(grams) of the substance your finding The c is the specific heat capacity of the object(it’s unique for each subject at each state of matter
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q= m x c x T continued The specific heat for water is 4.18 joules/(grams x degrees C) or 1 cal/(grams x degrees C) T- is the temperature change (T(final)- T(initial))
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Thermochemical Equation H= #Kj Mass 1 mol #Kj #grams # moles from equation - H= exothermic (hot) + H= endothermic (cold) Heat: mole ratio (from balanced equation On product side On reactant side
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Conversions 4.18 joules= 1 calorie 1000 joule= 1 kilojoules 1000 calories= 1 kilocalorie Calories x 4.18 joules Joules / 4.18 calories Calories/ Joules /1000 kcal/kjoules Kcal/ kjoules x1000 calories/ joules
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Temp Time A E D C B A- solid B-melting and freezing point C- liquid D- Boiling point and condensation E- Gas When solid skips the liquid stage and goes strait to gas this is called sublimation States of matter
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Endothermic and Exothermic reactions In an endothermic reaction the substance gets colder because the Energy enters the substance Ex: Ice pack In an exothermic reaction the substance gets hot because the energy leaves the substance giving off heat Ex: soup
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How much heat is absorbed by 250-g of water as the temperature changes from 25 degrees C to 35 degrees C?
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90.0- cal are added to a sample of water at 15 degrees C, the temperature of the water rises 35 degrees C. What was the mass of the sample of water?
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How much heat would be released when 3.60-g of ethanol, C 2 H 5 OH, is burned in the following reaction? C 2 H 5 OH + 3 O 2 2 CO 2 + 3 H 2 O + 1367 kJ
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