Heating and Cooling Curves PDF

HEATING AND COOLING CURVES Credit to: Harry S. Truman High School Chemistry Department What are some things that happen as we heat a sample up? Solid  Liquid  Gas Melting, Evaporating What is heat? How is heat different from temperature? Heat is a measure of kinetic or translat...

HEATING AND COOLING CURVES Credit to: Harry S. Truman High School Chemistry Department What are some things that happen as we heat a sample up? Solid  Liquid  Gas Melting, Evaporating What is heat? How is heat different from temperature? Heat is a measure of kinetic or translational energy  Inchemistry heat is measure in Joules (J)  Heat is dependent on mass, temperature change and specific heat (or ability of a substance to absorb heat) Temperature is a measure of warmth or coldness.  Temperature is independent of heat  Temperature is measured in Kelvin (K) or Celsius (C) What is the heating curve? The heating curve is a graph which represents how a sample changes phases. As heat is added over time, the sample changes temperature and phase accordingly. Thus heating curve. How does the heating curve look? What are the parts of the heating curve? What are the parts of the heating curve? What are the parts of the heating curve? What are the parts of the heating curve? What are the parts of the heating curve? What are the parts of the heating curve? Why is the curve flat at some portions? Temperature is staying constant, but potential energy is decreasing During this time the solid completely becomes liquid (or liquid becomes solid) Why is the curve flat at some points? This is called the heat of fusion (Hf) in segment BC and heat of vaporization (Hv) in segment DE. Remember fusion is melting and vaporization is evaporation What is heat of fusion? What is heat of vaporization? Hf is the amount of energy needed to completely make a solid into a liquid Hv is the amount of energy needed to completely make a liquid into a gas Summary The heating curve is a useful tool to show us the changes in temperature, energy, and entropy as a sample is heated up. It give us detailed information about phases and phase changes of samples.