DE CHEMISTRY: King William High School

 Pure substances (elements & compounds) have definite composition  Mixture is two or more different substances physically combined  Homogeneous mixtures – uniform throughout (solution)  Heterogeneous mixtures – NOT uniform

 Solid – definite shape and volume  Liquid – definite volume; NOT shape  Gas – neither definite shape nor volume

 Physical properties – shape, color, MP, BP, FP  Chemical properties – describe a substance changing into something new (metal rusting)

 Physical change – changes in state (melting, freezing, etc.)  Chemical change – changes into a new substance

 Kinetic v. potential  Heat- energy associated with the motion of molecules  Units (Joule and calorie)  1 cal = J  1Cal = 1 kcal = 1000 cal  Convert 6.2 x 10 2 J to cal and Cal.

 Carbohydrate = 4kcal/g  Fat = 9 kcal/g  Protein = 4 kcal/g  EX: You eat a meal that has 37 g of carbs, 19 g of fat and 23 g of protein. How many Calories did you intake?

 Q = cm  T  Table 3.11 on page 74  How much heat is released when 7 g of copper is cooled from 20 o C to 10 o C?

 Melting and freezing points  Heat of fusion – energy needed to melt a substance  Heat = mass x heat of fusion  How much heat will be absorbed from 26.0 g of ice in a soft drink at 0 o C if the heat of fusion = 334 j/g?

 Heat of vaporization – energy required to turn a liquid to a gas at its BP  Heat = mass x heat of vap.

 Page 81

 Opposite of heating curves

 How much energy is needed to heat 100 g of diethyl ether from 5 o C to its boiling point and boil it? The specific heat is 2.33 J/g o C. The heat of vaporization is 357 j/g.