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Chapter 17 pgs. 505- 533. 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.

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Presentation on theme: "Chapter 17 pgs. 505- 533. 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."— Presentation transcript:

1 Chapter 17 pgs. 505- 533

2 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

3 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))

4 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

5 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

6 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

7 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

8 How much heat is absorbed by 250-g of water as the temperature changes from 25 degrees C to 35 degrees C?

9 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?

10 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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