Energy • Energy: the ability to do work – Potential Energy: stored energy – Kinetic Energy: energy of motion • Heat: – Energy associated with motion of particles – Units: • joule (J) • kilojoule (kJ) • calorie (cal) – The energy needed to raise the temperature of 1 g of water by 1˚C 1 = 4.184 J (exact number)
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Energy Energy: the ability to do work –Potential Energy: stored energy –Kinetic Energy: energy of motion Heat: –Energy associated with motion of particles.
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Energy• Energy: the ability to do work
– Potential Energy: stored energy– Kinetic Energy: energy of motion
• Heat:– Energy associated with motion of particles– Units:
• joule (J)
• kilojoule (kJ)
• calorie (cal)– The energy needed to raise the temperature of 1
g of water by 1˚C
1
= 4.184 J
(exact number)
Energy in Chemical Reactions• Activation energy: energy needed for reaction to
occur– “hill” we must climb over
• Heat of reaction: – Amount of heat absorbed or released during a reaction
– Exothermic: heat is released– Endothermic: heat is absorbed 2
reactantsproducts HHH 0H0H
Identify each reaction as
Ex) exothermic or En) endothermic.
A. N2 + 3H2 2NH3 + 22 kcal
B. CaCO3 + 133 kcal CaO + CO2
C. 2SO2 + O2 2SO3 + heat
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Calculation using Heat of Reaction
The reaction occurring in a cold pack is as follows:
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(aq)(s) NONH NONHkcal 6.2 34OH
342
• Is this reaction exothermic or endothermic?
• If 10. g of ammonium nitrate is contained in the pack, how much heat can be absorbed or released if it reacts completely?
34NONH g 10.34
34
NONH g 50.80
NONH mole 1
Convert to moles!
34NONH mole 1
absorbed kcal 6.2
Moles energy?Energy is a
reactant!
774516.0
absorbed kcal 77.0
In the reaction
N2(g) + O2 (g) 2NO(g) ΔH = 43.2 kcal
N2(g) + O2 (g) + 43.2 kcal 2NO(g)
If 15.0 g NO are produced, how many kcal wereabsorbed?
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Specific Heat (SH)The amount of heat needed to raise the temperature
of 1 g of a substance by 1 °C
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Tgrams
heatSH
How much energy is needed to raise the temperature of 20.0 g of iron by 14.5 °C?
• A hot-water bottle contains 750 g of water at 65°C. If the water cools to body temperature (37°C), how many calories of heat could be transferred to sore muscles?
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Energy and Nutrition & Calculation
• Nutritional Calorie = Cal= 1 kcal = 1000 cal
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g 1
kcal 4
g 1
kcal 9
g 1
kcal 4
Carbohydrate
Fat(lipid)
Protein
Caloric Values:
food
water
Entropy
• Entropy– Entropy Describes degree of disorder– Increasing disorder helps drive reactions– Changes in disorder are indicated by ΔS
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Gibbs Free Energy
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• Used to determine if reaction is spontaneous or not• Takes into consideration heat of reaction,
temperature and entropy• Negative ΔG is spontaneous and positive ΔG is
nonspontaneous
States of Matter
Matter: anything that occupies space and has mass
Physical states:• Solid• Liquid• Gas (vapor)
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Shape?
Volume?
Arrangement of particles?
Interaction between particles?
Movement of particles?
Attractive forces between particles hold substances together
• Dipole-dipole• Hydrogen bonds• Dispersion
Intermolecular forces
Intermolecular Forces• Dipole-dipole:
– Polar molecules act like magnets– Ex. HCl and HCl
• Hydrogen bonds:– Strongest dipole-dipole interaction– Only occur between: