Do Now and Announcements Turn in HW and work on Do Now

Label the following diagram indicating vapor pressure (VP) and atmospheric/air pressure (AP):

By putting ice on top of the flask Temp of air inside flask: Pressure of air inside flask: **Explain, in terms of temperature change, atmospheric pressure, and vapor pressure, what happened in the demonstration

Definitions Kinetic Energy=the energy associated with moving particles (i.e. atoms) Temperature=measure of the average kinetic energy of a sample of a substance. Heat=is measured as the energy that is transferred from one object to another because of a difference in temperature. The direction of heat flow is always from the hotter object to the colder object.

Demo

Specific Heat Capacity: The amount of energy needed to raise the temperature of 1 gram of a substance by 1°C Heat = Energy transferred due to a difference in temperatures. The amount of heat absorbed or released in a physical or chemical reaction can be calculated using the equation q = mCΔT

Example

Station 2 question 3: The temperature of a sample of water in the liquid phase is raised from 20°C to 50°C by the addition of 3762 Joules. What is the mass of water?

Station Questions

Answer questions 1-7 based on the “Heating Curve”

1. During which 3 line segments does the temperature of the substance increase? 2. During which 2 line segments does the temperature of the substance remain the same?   3. At which point do the molecules of the substance have the lowest average kinetic energy? The highest?   AB, CD, and EF BC and DE Lowest average KE: A Highest average KE: F

4. Which phases of matter are present during segment BC?   5. Which phases of matter are present during segment DE? 6. Even though heat is being added to the substance the entire time, why do you think there is no change in temperature during segments BC and DE? Where do you think the heat energy is going or being used for?    7. Comparing segments B–C and D–E, what information is conveyed by the observation that segment D–E is longer? Solid and liquid Liquid and gas The heat is being used to melt the substance (BC) or boil it (DE) It takes more heat energy to boil the substance than it does to melt it

Kinetic vs. Potential Energy Kinetic Energy=the energy associated with moving particles; related to temperature. Potential Energy=the energy associated with the spaces between the atoms/molecules in a substance. It is NOT related to temperature; it is related with phase change

*Heat energy is being transferred to either KE or PE *When KE is changing, PE remains constant *When PE is changing, KE remains constant ↑ ↑ None (molecules still pretty close together) None None ↑ (Molecules are getting further apart as solid changes into liquid) None ↑ ↑ (molecules still loosely together) None None ↑ (Molecules are getting further apart as liquid changes into gas) ↑ ↑ None (molecules still far apart)

gas condensation liquid freezing solid We can also apply the same concepts to a cooling curve, in which a substance is cooled (or heat is removed from a substance) over time. ↓ ↓ None (molecules still far apart) None None ↓ (Molecules are getting closer together as gas changes into liquid) ↓ ↓ None (molecules still loosely together) ↓ (Molecules are getting closer together as liquid changes into solid) None None ↓ ↓ None (molecules still pretty close together)