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This deck focuses on Bond Enthalpies, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.
AP Chemistry Flashcards: Bond Enthalpies
Study Bond Enthalpies in AP Chemistry with focused flashcards that help you recognize the idea, recall the key rule, and apply it in practice-style prompts.
AP Chemistry
Bond Enthalpies
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What is the bond enthalpy of a C-H bond in kJ/mol?
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ANSWER
Approximately 413 kJ/mol. Common value for single C-H bonds in organic molecules.
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Flashcard 1: What is the bond enthalpy of a C-H bond in kJ/mol?
Answer: Approximately 413 kJ/mol. Common value for single C-H bonds in organic molecules.
Flashcard 2: How does bond strength relate to bond enthalpy?
Answer: Stronger bonds have higher bond enthalpies. Higher enthalpy means more energy needed to break the bond.
Flashcard 3: Identify the bond with the highest bond enthalpy: C-H, N≡N, O=O.
Answer: N≡N. N≡N has the highest enthalpy due to triple bonding.
Flashcard 4: How does bond strength relate to bond enthalpy?
Answer: Stronger bonds have higher bond enthalpies. Higher enthalpy means more energy needed to break the bond.
Flashcard 5: What is the bond enthalpy of an F-F bond?
Answer: 157 kJ/mol. Weak bond due to lone pair repulsion between fluorines.
Flashcard 6: Calculate the bond enthalpy change for breaking 2 Cl-Cl and forming 2 Cl-H. Use 242 and 431 kJ/mol.
Answer: ΔH=2(242)−2(431)=−378 kJ/mol. Breaking uses 484 kJ/mol, forming releases 862 kJ/mol.
Flashcard 7: What is the bond enthalpy of a N=N bond?
Answer: 418 kJ/mol. Standard value for nitrogen-nitrogen double bonds.
Flashcard 8: What is the bond enthalpy of a H-Cl bond?
Answer: 431 kJ/mol. Standard value for hydrogen-chlorine bonds in HCl.
Flashcard 9: What is the bond enthalpy of a C≡C bond?
Answer: 839 kJ/mol. Standard value for carbon-carbon triple bonds.
Flashcard 10: Calculate the bond enthalpy change: breaking 2 H-H and forming 2 H-O. Use 436 kJ/mol (H-H) and 463 kJ/mol (H-O).
Answer: ΔH=2(436)−2(463)=−54 kJ/mol. Breaking requires 872 kJ/mol, forming releases 926 kJ/mol.
Flashcard 11: What type of reaction is indicated if the total bond enthalpies of products are greater than reactants?
Answer: Endothermic reaction. More energy required to break bonds than released forming them.
Flashcard 12: What type of reaction is indicated if the total bond enthalpies of products are greater than reactants?
Answer: Endothermic reaction. More energy required to break bonds than released forming them.
Flashcard 13: Identify whether a reaction is endothermic or exothermic when ΔH is positive.
Answer: Endothermic. Positive ΔH means energy is absorbed from surroundings.
Flashcard 14: What happens to bond enthalpy as bond length increases?
Answer: Bond enthalpy decreases. Longer bonds have weaker attractive forces between atoms.
Flashcard 15: What is the bond enthalpy of a C-H bond in kJ/mol?
Answer: Approximately 413 kJ/mol. Common value for single C-H bonds in organic molecules.
Flashcard 16: What is the bond enthalpy of a C-O bond in methanol?
Answer: 358 kJ/mol. Standard value for carbon-oxygen single bonds.
Flashcard 17: What is the bond enthalpy of a C-Cl bond?
Answer: 328 kJ/mol. Standard value for carbon-chlorine single bonds.
Flashcard 18: State whether breaking a bond is endothermic or exothermic.
Answer: Endothermic. Energy is required to overcome attractive forces between atoms.
Flashcard 19: What is the bond enthalpy of an O=O bond?
Answer: 498 kJ/mol. Strong double bond between oxygen atoms in O2.
Flashcard 20: Which bond typically has a higher bond enthalpy: C=C or C-C?
Answer: C=C. Double bonds are stronger than single bonds.
Flashcard 21: What is the bond enthalpy of a C-H bond in kJ/mol?
Answer: Approximately 413 kJ/mol. Common value for single C-H bonds in organic molecules.
Flashcard 22: Calculate the enthalpy change: breaking H-H and Cl-Cl, forming 2 H-Cl. Use 436, 242, and 431 kJ/mol.
Answer: ΔH=(436+242)−2(431)=−184 kJ/mol. Breaking uses 678 kJ/mol, forming releases 862 kJ/mol.
Flashcard 23: Calculate the bond enthalpy change for breaking 1 O=O and forming 2 O-H bonds. Use 498 and 463 kJ/mol.
Answer: ΔH=498−2(463)=−428 kJ/mol. Breaking uses 498 kJ/mol, forming releases 926 kJ/mol.
Flashcard 24: Calculate the bond enthalpy change for breaking 1 O=O and forming 2 O-H bonds. Use 498 and 463 kJ/mol.
Answer: ΔH=498−2(463)=−428 kJ/mol. Breaking uses 498 kJ/mol, forming releases 926 kJ/mol.
Flashcard 25: Calculate the bond enthalpy change for breaking 2 Cl-Cl and forming 2 Cl-H. Use 242 and 431 kJ/mol.
Answer: ΔH=2(242)−2(431)=−378 kJ/mol. Breaking uses 484 kJ/mol, forming releases 862 kJ/mol.
Flashcard 26: What is the bond enthalpy of an O=O bond?
Answer: 498 kJ/mol. Strong double bond between oxygen atoms in O2.
Flashcard 27: What is the bond enthalpy of an F-F bond?
Answer: 157 kJ/mol. Weak bond due to lone pair repulsion between fluorines.
Flashcard 28: Calculate the enthalpy change: breaking H-H and Cl-Cl, forming 2 H-Cl. Use 436, 242, and 431 kJ/mol.
Answer: ΔH=(436+242)−2(431)=−184 kJ/mol. Breaking uses 678 kJ/mol, forming releases 862 kJ/mol.
Flashcard 29: What is the bond enthalpy of a C≡C bond?
Answer: 839 kJ/mol. Standard value for carbon-carbon triple bonds.
Flashcard 30: What is the bond enthalpy of an O=O bond?
Answer: 498 kJ/mol. Strong double bond between oxygen atoms in O2.
Flashcard 31: What is the bond enthalpy of an F-F bond?
Answer: 157 kJ/mol. Weak bond due to lone pair repulsion between fluorines.
Flashcard 32: Identify the bond with the highest bond enthalpy: C-H, N≡N, O=O.
Answer: N≡N. N≡N has the highest enthalpy due to triple bonding.
Flashcard 33: What is the bond enthalpy of a C=O bond in carbon dioxide?
Answer: 799 kJ/mol. Strong double bond in carbon dioxide molecule.
Flashcard 34: Calculate the bond enthalpy change for breaking N≡N and forming 2 N-H bonds. Use 941 and 391 kJ/mol.
Answer: ΔH=941−2(391)=159 kJ/mol. Breaking uses 941 kJ/mol, forming releases 782 kJ/mol.
Flashcard 35: State whether forming a bond is endothermic or exothermic.
Answer: Exothermic. Energy is released when atoms come together to form bonds.
Flashcard 36: Identify the bond with the highest bond enthalpy: C-H, N≡N, O=O.
Answer: N≡N. N≡N has the highest enthalpy due to triple bonding.
Flashcard 37: Which bond is generally stronger, N≡N or N=N?
Answer: N≡N. Triple bonds have higher bond enthalpies than double bonds.
Flashcard 38: State the formula for calculating the change in enthalpy using bond enthalpies.
Answer: ΔH=∑(bond enthalpies of bonds broken)−∑(bond enthalpies of bonds formed). Energy in minus energy out gives the net enthalpy change.
Flashcard 39: What is the bond enthalpy of an O-H bond?
Answer: 463 kJ/mol. Standard value for oxygen-hydrogen bonds in water.
Flashcard 40: What happens to bond enthalpy as bond length increases?
Answer: Bond enthalpy decreases. Longer bonds have weaker attractive forces between atoms.
Flashcard 41: Identify the unit commonly used for bond enthalpy.
Answer: Kilojoules per mole (kJ/mol). Standard unit for expressing energy per mole of substance.
Flashcard 42: What is the definition of bond enthalpy?
Answer: The energy required to break one mole of a bond in gaseous molecules. Always measured for gaseous species at standard conditions.
Flashcard 43: What is the bond enthalpy of a N=N bond?
Answer: 418 kJ/mol. Standard value for nitrogen-nitrogen double bonds.
Flashcard 44: What is the definition of bond enthalpy?
Answer: The energy required to break one mole of a bond in gaseous molecules. Always measured for gaseous species at standard conditions.
Flashcard 45: State whether forming a bond is endothermic or exothermic.
Answer: Exothermic. Energy is released when atoms come together to form bonds.
Flashcard 46: Compare bond enthalpies: O-H vs C-H.
Answer: O-H > C-H. O-H bond (463) is stronger than C-H bond (413).
Flashcard 47: State whether breaking a bond is endothermic or exothermic.
Answer: Endothermic. Energy is required to overcome attractive forces between atoms.
Flashcard 48: State whether breaking a bond is endothermic or exothermic.
Answer: Endothermic. Energy is required to overcome attractive forces between atoms.
Flashcard 49: What factor primarily affects the bond enthalpy?
Answer: Bond strength. Bond enthalpy reflects the energy needed to break bonds.
Flashcard 50: What is the bond enthalpy of a C-C bond?
Answer: 348 kJ/mol. Standard value for single carbon-carbon bonds.
Flashcard 51: What is the bond enthalpy of an N-H bond?
Answer: 391 kJ/mol. Standard value for nitrogen-hydrogen single bonds.
Flashcard 52: Identify whether a reaction is endothermic or exothermic when ΔH is positive.
Answer: Endothermic. Positive ΔH means energy is absorbed from surroundings.
Flashcard 53: What is the bond enthalpy of a C≡C bond?
Answer: 839 kJ/mol. Standard value for carbon-carbon triple bonds.
Flashcard 54: What is the bond enthalpy of a C-Cl bond?
Answer: 328 kJ/mol. Standard value for carbon-chlorine single bonds.
Flashcard 55: What is the bond enthalpy of a C=O bond in carbon dioxide?
Answer: 799 kJ/mol. Strong double bond in carbon dioxide molecule.
Flashcard 56: What factor primarily affects the bond enthalpy?
Answer: Bond strength. Bond enthalpy reflects the energy needed to break bonds.
Flashcard 57: What is the bond enthalpy of an F-F bond?
Answer: 157 kJ/mol. Weak bond due to lone pair repulsion between fluorines.
Flashcard 58: Compare bond enthalpies: O-H vs C-H.
Answer: O-H > C-H. O-H bond (463) is stronger than C-H bond (413).
Flashcard 59: Calculate the bond enthalpy change for breaking N≡N and forming 2 N-H bonds. Use 941 and 391 kJ/mol.
Answer: ΔH=941−2(391)=159 kJ/mol. Breaking uses 941 kJ/mol, forming releases 782 kJ/mol.
Flashcard 60: What is the bond enthalpy of a C-N bond?
Answer: 305 kJ/mol. Standard value for carbon-nitrogen single bonds.
Flashcard 61: Which has a higher bond enthalpy: a single bond or a triple bond?
Answer: A triple bond. More bonds mean stronger attraction and higher enthalpy.
Flashcard 62: What factor primarily affects the bond enthalpy?
Answer: Bond strength. Bond enthalpy reflects the energy needed to break bonds.
Flashcard 63: What is the bond enthalpy of an N-H bond?
Answer: 391 kJ/mol. Standard value for nitrogen-hydrogen single bonds.
Flashcard 64: What is the bond enthalpy of an N-H bond?
Answer: 391 kJ/mol. Standard value for nitrogen-hydrogen single bonds.
Flashcard 65: Which bond typically has a higher bond enthalpy: C=C or C-C?
Answer: C=C. Double bonds are stronger than single bonds.
Flashcard 66: What is the bond enthalpy of an O=O bond?
Answer: 498 kJ/mol. Strong double bond between oxygen atoms in O2.
Flashcard 67: What is the bond enthalpy of a N=N bond?
Answer: 418 kJ/mol. Standard value for nitrogen-nitrogen double bonds.
Flashcard 68: Which bond is generally stronger, N≡N or N=N?
Answer: N≡N. Triple bonds have higher bond enthalpies than double bonds.
Flashcard 69: Compare bond enthalpies: O-H vs C-H.
Answer: O-H > C-H. O-H bond (463) is stronger than C-H bond (413).
Flashcard 70: What factor primarily affects the bond enthalpy?
Answer: Bond strength. Bond enthalpy reflects the energy needed to break bonds.
Flashcard 71: What is the definition of bond enthalpy?
Answer: The energy required to break one mole of a bond in gaseous molecules. Always measured for gaseous species at standard conditions.
Flashcard 72: Calculate the bond enthalpy change: breaking 2 H-H and forming 2 H-O. Use 436 kJ/mol (H-H) and 463 kJ/mol (H-O).
Answer: ΔH=2(436)−2(463)=−54 kJ/mol. Breaking requires 872 kJ/mol, forming releases 926 kJ/mol.
Flashcard 73: Calculate the bond enthalpy change: breaking 1 C-C and forming 2 C-H. Use 348 and 413 kJ/mol.
Answer: ΔH=348−2(413)=−478 kJ/mol. Breaking uses 348 kJ/mol, forming releases 826 kJ/mol.
Flashcard 74: What is the bond enthalpy of a C-H bond in kJ/mol?
Answer: Approximately 413 kJ/mol. Common value for single C-H bonds in organic molecules.
Flashcard 75: What is the bond enthalpy of a C=O bond in carbon dioxide?
Answer: 799 kJ/mol. Strong double bond in carbon dioxide molecule.
Flashcard 76: Calculate the bond enthalpy change for breaking 1 O=O and forming 2 O-H bonds. Use 498 and 463 kJ/mol.
Answer: ΔH=498−2(463)=−428 kJ/mol. Breaking uses 498 kJ/mol, forming releases 926 kJ/mol.
Flashcard 77: State whether breaking a bond is endothermic or exothermic.
Answer: Endothermic. Energy is required to overcome attractive forces between atoms.
Flashcard 78: Calculate the bond enthalpy change for breaking 2 C=C and forming 3 C-C. Use 614 and 348 kJ/mol.
Answer: ΔH=2(614)−3(348)=240 kJ/mol. Breaking uses 1228 kJ/mol, forming releases 1044 kJ/mol.
Flashcard 79: What is the definition of bond enthalpy?
Answer: The energy required to break one mole of a bond in gaseous molecules. Always measured for gaseous species at standard conditions.
Flashcard 80: Calculate the bond enthalpy change for breaking 1 O=O and forming 2 O-H bonds. Use 498 and 463 kJ/mol.
Answer: ΔH=498−2(463)=−428 kJ/mol. Breaking uses 498 kJ/mol, forming releases 926 kJ/mol.
Flashcard 81: What type of reaction is indicated if the total bond enthalpies of products are greater than reactants?
Answer: Endothermic reaction. More energy required to break bonds than released forming them.
Flashcard 82: What type of reaction is indicated if the total bond enthalpies of products are greater than reactants?
Answer: Endothermic reaction. More energy required to break bonds than released forming them.
Flashcard 83: How does bond strength relate to bond enthalpy?
Answer: Stronger bonds have higher bond enthalpies. Higher enthalpy means more energy needed to break the bond.
Flashcard 84: Which bond is generally stronger, N≡N or N=N?
Answer: N≡N. Triple bonds have higher bond enthalpies than double bonds.
Flashcard 85: Calculate the bond enthalpy change for breaking N≡N and forming 2 N-H bonds. Use 941 and 391 kJ/mol.
Answer: ΔH=941−2(391)=159 kJ/mol. Breaking uses 941 kJ/mol, forming releases 782 kJ/mol.
Flashcard 86: What is the bond enthalpy of a N=N bond?
Answer: 418 kJ/mol. Standard value for nitrogen-nitrogen double bonds.
Flashcard 87: What does a negative enthalpy change indicate about a reaction?
Answer: The reaction is exothermic. Energy is released to the surroundings during reaction.
Flashcard 88: State whether forming a bond is endothermic or exothermic.
Answer: Exothermic. Energy is released when atoms come together to form bonds.
Flashcard 89: Compare bond enthalpies: O-H vs C-H.
Answer: O-H > C-H. O-H bond (463) is stronger than C-H bond (413).
Flashcard 90: State whether forming a bond is endothermic or exothermic.
Answer: Exothermic. Energy is released when atoms come together to form bonds.
Flashcard 91: Identify whether a reaction is endothermic or exothermic when ΔH is positive.
Answer: Endothermic. Positive ΔH means energy is absorbed from surroundings.
Flashcard 92: What is the bond enthalpy of an N-H bond?
Answer: 391 kJ/mol. Standard value for nitrogen-hydrogen single bonds.
Flashcard 93: Which bond is generally stronger, N≡N or N=N?
Answer: N≡N. Triple bonds have higher bond enthalpies than double bonds.
Flashcard 94: How does bond strength relate to bond enthalpy?
Answer: Stronger bonds have higher bond enthalpies. Higher enthalpy means more energy needed to break the bond.
Flashcard 95: What does a negative enthalpy change indicate about a reaction?
Answer: The reaction is exothermic. Energy is released to the surroundings during reaction.
Flashcard 96: What happens to bond enthalpy as bond length increases?
Answer: Bond enthalpy decreases. Longer bonds have weaker attractive forces between atoms.
Flashcard 97: Calculate the enthalpy change: breaking H-H and Cl-Cl, forming 2 H-Cl. Use 436, 242, and 431 kJ/mol.
Answer: ΔH=(436+242)−2(431)=−184 kJ/mol. Breaking uses 678 kJ/mol, forming releases 862 kJ/mol.
Flashcard 98: What happens to bond enthalpy as bond length increases?
Answer: Bond enthalpy decreases. Longer bonds have weaker attractive forces between atoms.
Flashcard 99: What is the bond enthalpy of a C=O bond in carbon dioxide?
Answer: 799 kJ/mol. Strong double bond in carbon dioxide molecule.
Flashcard 100: Calculate the enthalpy change: breaking H-H and Cl-Cl, forming 2 H-Cl. Use 436, 242, and 431 kJ/mol.
Answer: ΔH=(436+242)−2(431)=−184 kJ/mol. Breaking uses 678 kJ/mol, forming releases 862 kJ/mol.