MELC-107-109-PHASE-DIAGRAM-HEATING-CURVE (1).pdf

Phase Diagram Water and Carbon Dioxide  Most Essential Learning Competency Interpret the phase diagram of water and carbon dioxide. (STEM_GC11IMF-IIIa-c-107) Learning Objectives: At the end of the lesson, the learners will be able to: 1. describe the components of a phase diagram; 2. use...

Phase Diagram Water and Carbon Dioxide  Most Essential Learning Competency Interpret the phase diagram of water and carbon dioxide. (STEM_GC11IMF-IIIa-c-107) Learning Objectives: At the end of the lesson, the learners will be able to: 1. describe the components of a phase diagram; 2. use phase diagrams of pure substances to determine its phase at given temperature and pressure; 3. interpret the phase diagram of water and carbon dioxide; 4. describe how changes in temperature and pressure can change the state of matter; and 5. construct a phase diagram of a substance from given data. Focus Question: 1. How can this effect be achieved using CO₂ or dry ice? 2. What does LPG stand for? How can a gas be liquefied? What conditions are needed to convert a gas into a liquid? What’s in the Phase Diagram? A phase diagram is a graphical representation of the physical states of a substance under different conditions of temperature and pressure. It gives the possible combinations of pressure and temperature at which certain physical state or states a substance would be observed. Each substance has its own phase diagram. What are the features of a phase diagram? Phase diagrams are plots of pressure (usually in atmospheres) versus temperature (usually in ºC or K). A. The Three Areas The three areas are marked solid (A), liquid (B), and vapor (C). B. Three Lines (Curves) 1. Melting (or freezing) curve – the curve on a phase diagram which represents the transition between liquid and solid states. It shows the effect of pressure on the melting point of the solid. 2. Vaporization (or condensation) curve – the curve on a phase diagram which represents the transition between gaseous and liquid states. It shows the effect of pressure on the boiling point of the liquid. 3. Sublimation (or deposition) curve – the curve on a phase diagram which represents the transition between gaseous and solid states. It represents the effect of increased temperature on a solid at a very low constant pressure, lower than the triple point. B. Three Lines (Curves) C. Two Important Points 1. The triple point The triple point is a unique combination of pressure and temperature where all three phases of matter are at equilibrium together. It is the point on a phase diagram at which the three states of matter coexist. The lines that represent the conditions of solid- liquid, liquid-vapor, and solid-vapor equilibrium meet at the triple point. C. Two Important Points 1. The triple point C. Two Important Points 2. The critical point The critical point terminates the liquid/gas phase line. It is the set of temperature and pressure on a phase diagram where the liquid and gaseous phases of a substance merge together into a single phase. Beyond the temperature of the critical point, the merged single phase is known as a supercritical fluid. A supercritical fluid (SCF) is a material that can be either liquid or gas, used in a state above the critical temperature and critical pressure where gases and liquids can coexist. C. Two Important Points 2. The critical point The Phase Diagram for Water There is only one difference between the phase diagram for water and the other phase diagrams. The solid-liquid equilibrium line (the melting point curve) slopes backwards rather than forwards. For water, the melting point gets lower at higher pressures. This is because solid ice is less dense than liquid water The Phase Diagram for Water Slope Backward Slope Forward The Phase Diagram for Water An increase in pressure will move the above equilibrium to the side with the smaller volume, liquid water is produced. To make the liquid water freeze again at this higher pressure, the temperature should be reduced. The triple temperature of water is 273.16 K at P = 0.0060373 atm At P < 0.00604 atm., ice will not melt into a liquid form as the temperature increases; the ice will directly sublime to water vapor. The Phase Diagram for Water The Phase Diagram for Water The water reaches the critical point at 373.99 ºC, having a pressure of 217.7 atm. Critical Point of Some Simple Substances The Phase Diagram for Carbon Dioxide The only thing special about this phase diagram is the position of the triple point, which is well above atmospheric pressure. It is impossible to get any liquid carbon dioxide at pressures less than 5.2 atmospheres. At 1 atm pressure, carbon dioxide will sublime at a temperature of 197.5 K (-75.5 °C). This is the reason why solid carbon dioxide is often known as "dry ice." There is no liquid carbon dioxide under normal conditions (1 atm) - only the solid or the vapor. The Phase Diagram for Carbon Dioxide The Phase Diagram for Carbon Dioxide Carbon dioxide has no normal melting point but a normal sublimation point at -75.5 °C. The critical point of CO₂ is within the range of T = 30.98 ºC and P = 72.79 atm.  Activity 1. Let’s PHASE it! Learning Objectives: 1. Describe the components/ features of a phase diagram; 2. Analyze the phase diagram of water and carbon dioxide; and 3. Interpret phase diagrams of pure substances to determine their phase at the given temperature and pressure. What you need: Pen, ruler, marker Part I. Phase Diagram Analysis Direction: Use the phase diagram of water to complete the table below and answer the guide question as follows. Activity 1. Let’s PHASE it! Phase Diagram of Water Activity 1. Let’s PHASE it! Phase Diagram of Water Activity 1. Let’s PHASE it!  Activity 1. Let’s PHASE it! Guide Question: 1. What is the critical temperature of water? 2. At what temperature will a triple point occur for water? 3. How will the pressure lesser than 0.00604 atm. at normal boiling point influence the phase change of the water? 4. Will phase change happens to water at 1 atm. as the temperature rises from –15°C to 60°C? Support your answer. 5. Describe the phase of ice and water vapor in terms of the function of temperature and pressure. Most Essential Learning Competency (LAB) Determine and explain the heating and cooling curve of a substance. (STEM_GC11IMF-IIIa-c-109) Specific Learning Outcomes: At the end of the lesson, the learners will be able to: 1. construct and interpret a heating curve for water; 2. construct heating and cooling curves of a pure substance using experimental data; and 3. demonstrate how heat energy can be used to raise the temperature of a substance and weaken intermolecular forces to cause a phase change. A heating curve Heating curve for water  30 DEPARTMENT OF EDUCATION-BUREAU OF CURRICULUM DEVELOPMENT