What’s the MATTER: Specific Heat of Matter

Matter, Specific Heat of Matter At the conclusion of our time together, you should be able to: 1. Define specific heat 2. Use specific heat to determine energy changes

Thermochemistry  Some Definitions: Calorimeter – a device to measure the energy absorbed or released as heat in a chemical or physical change Temperature – measure of the average kinetic energy of the particles in a sample of matter Joule – the SI unit of heat

Thermochemistry  Some Definitions: Heat – energy transferred between samples of matter Specific Heat – the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree or one Kelvin 1 Calorie/4.184 Joules – will do the above with water

Thermochemistry  Some Definitions: Enthalpy (Heat) of Fusion – amount of energy gained or lost by a system as heat during melting or freezing Enthalpy (Heat) of Vaporization – amount of energy gained or lost by a system as heat during boiling or condensation

Specific Heat Calculations:  q = c p x m x t: q = energy lost or gained c p = specific heat of the substance at a specific pressure m = mass of the sample t = change in temperature (final – initial)

Practice #1  q = c p x m x t: q = J c p = x m = g t = o C J = (x)( g)(152.0 o C) = J/g o C

Practice #2  q = c p x m x t: q = J c p = J/g o C m = g t = (x – o C) J = J / g o C ( g)(x – o C) = 30.81x – = 30.81x = 76.0 o C

Matter, Specific Heat of Matter Let’s see if you can : 1. Define specific heat 2. Use specific heat to determine energy changes

Define Specific Heat Specific Heat – the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree or one Kelvin

Practice #3  q = c p x m x t: q = J c p = J/g o C m = x g t = o C J = (0.440 J/g o C )(x)(-1475 o C) J = -649 Jg = 0.29 g

Practice #4  q = c p x m x t: q = x J c p = cal/g o C (4.184 J/cal) m = g t = o C x = ( J/g o C )( g)(-51.5 o C) = x 10 3 J