Transcript Slide 1
Temperature (oC) Phase-Change Diagram Heat = mass x ΔT x Cg Gas Hvap = -∆Hcond Heat = mass x HVaporization l↔g B pt Condensation pt Liquid Heat = mass x ΔT x Cl Hfus = -∆Hsolid Heat = mass x HFusion M pt s ↔ l Freezing pt Solid Heat = mass x ΔT x Cs HFusion Heat (J) HVaporization Heat of Fusion - energy required to change 1 gram of a solid into a liquid at its melting point. Water (∆Hfus) = 335 J / g = -∆Hsolid Heat of Vaporization - energy required to change 1 gram of a liquid into a gas at its normal boiling point. Water (∆Hvap) = 2260 J / g = -∆Hcond Specific Heat - energy required to change the temperature of 1 gram of a substance by 1 oC. Water (Cl) = 4.18 J / goC Cs = 2.03 J / goC Cg = 2.01 J / goC Pg 2 1. When the substance changes from state X to Y It contains more energy It has a random arrangement of particle It will take the shape of a container when put in one All of the above 2. When the substance changes from state Y to state Z, It contains more energy It has a set arrangement of particles It will not take the shape of container when put in one None of the above When the substance is in state X, It is designated as A liquid A gas A solid A plasma From point A to point B the substance changes from a solid to a Gas Liquid Plasma All of these above From point C to point D, the substance changes From a liquid to a gas From a solid to a liquid From a liquid to a solid From a solid to a gas Energy added to the substance from point A to point B changes the substance’s Temperature State Chemical composition All of the above Energy added to the substance from point C to point D changes the substance’s State Arrangement of particle Density All of the above The temperature represented by line segment AB is the substance’s Melting point Melting or freezing point Freezing point Boiling point The temperature represented by line segment CD is the substance’s Melting point Melting or freezing point Freezing point Boiling point In general, as the temperature of a substance increases, the substance’s Chemical composition changes Energy content decreases Density decreases None of the above Pg 3 Does the temperature increase during melting? Is energy required for each phase change? No – T remains constant Yes – energy is required Can both liquid water and steam exist at 100°C? Yes What must be changed, temperature or heat energy, during condensation? Heat Energy must be removed How would you describe the change in the arrangement of particles as heat energy and temperature increase? More spread out – less dense What rule can you state about the relationship between phase changes and temperature? T does not change during a phase change Between phase changes and heat energy? Heat Energy is required or released during a phase change C A Gases are best represented by Diagram ______ B shows the state of matter with the greatest density. Diagram _________ plasma One state of matter that is not represented by the diagrams is __________. Liquids are best represented by Diagram ______ Pg 4 G F E l↔g D s↔l Melting point Circle the letter that corresponds to the freezing point 1. A B C D E F G Circle the letter that corresponds to the boiling point condensation point 2. A B C D E F G G F E l↔g D s↔l Circle the letter that corresponds to points where the substance is present only in the liquid state 3. A B C D E F G Circle the letter that corresponds to points where the substance is present in both the liquid and gaseous states 4. A B C D E F G G F E l↔g D s↔l Circle the letter that corresponds to points where the substance is present in both the solid and liquid states 5. A B C D E F G Circle the letter that corresponds to points where the substance is present only in the solid state 6. A B C D E F G G F E l↔g D s↔l Circle the letter that corresponds to points where the substance is present only in the gaseous state 7. A B C D E F G In a heat calculation problem, if the problem asks about melting/freezing you would multiply the mass times _________. a. Heat of fusion b. Heat of vaporization c. Specific heat Heat = mass x HFusion In a heat calculation problem, if the problem asks about a change in temperature, you would multiply the mass times_____________ times the change in temperature. a. Heat of fusion b. Heat of vaporization c. Specific heat Heat = mass x ΔT x C In a heat calculation problem, if the problem asks about vaporizing/condensing of steam, you would multiply the mass times _____________. a. Heat of fusion b. Heat of vaporization c. Specific heat Heat = mass x HVaporization