Converting Between Temperature and Energy for Solids and Liquids

1. Converting Between Temperature and Energy for Solids and Liquids The relationship between temperature and kinetic energy is different for each substance The relationship is expressed as specific heat for any substance. This is an empirical value. Specific Heat - J/g K

2. Specific Heat of Water - 4.184 J/gK

3. How much heat energy is needed to raise the temperature of 25 ml of water from 30 C to 40 C. Note: the specific heat of water is 4.18 J/g-K; assume the density of the water is 1.00 g ml -1. Mass of water = 25 grams  K = 10 K 25 g 4.18 J 10 K = 1120 J g K

4. The temperature of a 600.0 ml sample of water decreases from 25.0 to 19.0 C. How much heat energy is being used up. Note: the specific heat of water is 4.18 J/g-K and the density of water is 1.00 g per ml. Mass water = 600 ml 1 gram = 600 g 1 ml  K = 25 - 19 = 6 K 600 g 4.18 J 6 K = 15000 J = 15 kJ g K

5. A student mixes 50.0 ml of a 1 M HCl solution and 50.0 ml of a 1 M NaOH solution in a insulated calorimeter. The temperature of the resulting solution increases from 21.0 C to 27.5 C. Calculate enthalpy in kJ per mol HCl. The specific heat of water is 4.18 J/g-K. Assume the density of the solution is 1.0 g/ml. Enthalpy =  H = heat of reaction  K = 27.5 - 21 = 6.5  Hrxn= (100 g H2O) (4.18 J) (6.5 K) = 2717 J 1 kJ = -2.72 kJ g K 1000 J 50 ml 1 mol HCl = 0.05 mol HCl 1000 ml  Hmol = 1 mol -2.72 kJ = - 54.4 kJ/mol 0.05 mol