Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel...
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Transcript of Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel...
![Page 1: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/1.jpg)
Energy in Reaction
• Some reactions give off energy– Called _________– Examples:
– They feel _______
![Page 2: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/2.jpg)
Energy continued
• Some reactions take in energy– Called ___________– Examples:– They feel _________
![Page 3: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/3.jpg)
From your lab….
• What type of reaction was it?
• Where did the energy come from?
• What do we need to know to figure out how much energy was transferred?
![Page 4: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/4.jpg)
Energy Calculations
q = mCT
![Page 5: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/5.jpg)
Specific Heat
• Tells you how easily something heats up
![Page 6: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/6.jpg)
Specific heats
![Page 7: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/7.jpg)
Calculate your Q
![Page 8: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/8.jpg)
Heat of Combustion
• How much energy is given off when a substance is burned.
• Measured in kilojoules or kilocalories
![Page 9: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/9.jpg)
Heat of combustion
• Thermal energy/mass of substance burned
• Q/mass of candle burned
![Page 10: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/10.jpg)
Molar heat of combustion
• Amount of energy to burn 1 mole of a substance
• kJ/mol• Q/moles burned
![Page 11: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/11.jpg)
What is efficiency???
![Page 12: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/12.jpg)
What are some ways your car is inefficient?
![Page 13: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/13.jpg)
Where are some places your lab set up could have lost heat??
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Step 1
• Bonds need to be broken so that they can be rearranged– Endothermic - energy is needed
• Energy + CH4 + 2O2 C + 4H + 4O
• Energy must be added to “pull apart” the compounds
![Page 15: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/15.jpg)
Step 2
• The separate atoms need to form new bonds to make our products.– Exothermic change - energy is given off
• C + 4H + 4O CO2 + 2H2O + energy
![Page 16: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/16.jpg)
Ene
rgy
Reaction coordinate
Reactants
Products
2 Hydrogens1 Oxygen
2 Waters
![Page 17: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/17.jpg)
Overall Reaction
• The energy released when bonds are formed in CO2 and H2O is more than the energy needed to break the bonds of CH4 and O2
– Therefore, the total reaction is exothermic (gives off energy)
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Exo Vs Endo
• If the total reaction GIVES OFF heat it is exothermic
• If the total reaction REQUIRES HEAT it is endothermic
• If one reaction is exothermic, the complete opposite would be endothermic
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Ene
rgy
Reaction coordinate
Reactants
Products
Activation Energy Energy required to make the reaction happen
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Ene
rgy
Reaction coordinate
Reactants
Products
Heat released
Exothermic Reaction
![Page 21: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/21.jpg)
Ene
rgy
Reaction coordinate
Reactants
Products
Heat absorbed
Endothermic Reaction
![Page 22: Energy in Reaction Some reactions give off energy –Called _________ –Examples: –They feel _______.](https://reader036.fdocuments.us/reader036/viewer/2022070413/5697bfdb1a28abf838cb05a2/html5/thumbnails/22.jpg)
Practice Problems
• How many calories of heat are taken in when 10.0 g of water cool from 50.0 oC to 25.0 oC?
• Iron has a specific heat of 0.11 cal/gºC. How much heat will it take to change the temperature of 48.3 g of iron by 32.4ºC?