Chem_Heat_Test.docx - WS 1 Specific Heat Concepts Problems...

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WS 1 Specific Heat Concepts & Problems Heat is an extensive property whereas temperature is a intensive property, since it doesn’t depend on the amount of substance present Temperature: average kinetic energy Specific heat capacity- the amount of heat energy required to raise the temperature of a substance Possible units: cal/g *c or J/ g*c Insulators have a low specific heat Why? Because they need a low amount of heat to raise the temperature Energy Calculations: Q= mc (delta T) The mass multiplied by specific heat and the final minus the initial temperature 1 calorie= 4.184 Joules WS 2 Intermolecular Forces Intermolecular forces are forces found between molecules. While intramolecular forces are molecular bonds within the molecules that holds atoms together. Intermolecular forces are much weaker than covalent and ionic bonds. Intramolecular forces- covalent and ionic bonds Dipole- Dipole interactions are interactions that occur between molecules that have a permanent dipole moment (molecular polarity). All polar molecules are attracted to each other through dipole- dipole. Factors that affect strength: The strength of the dipole- dipole attraction depends on the magnitude of the dipole moment. Big EN → strong Dispersion forces are a temporary dipole that can attract another molecule for a short time. Electrons in molecules are in constant motion. At any instant, the electron distribution may be asymmetrical. Factors that affect strength depends on the number of electrons in a molecule and the ease with which their distribution can be disturbed. Hydrogen bonds are bonds that occur between a hydrogen covalently bonded to N, O, or F in one molecule and a nonbonding pair of electrons on N, O, or F in another molecule. Factors that affect strength is the degree of the dipole. London dispersion Forces
Electrons in molecules are in constant motion. At one instant, electrons can be mass on one side of the molecule This creates a temporary dipole that can attract another molecule for a short time More electrons = stronger LDF E- distributed over larger area =stronger LDFs Every molecule has london dispersion force Non polar molecules only have LDFs Dipole Dipole

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