For example! Matter and Its Phases. Matter and Its Changes Chemistry 11. Observations vs. Interpretations 2/1/09

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1 Matter and Its Phases Matter: Anything that has mass and occupies space. Matter and Its Changes Chemistry 11 Matter is anything that has mass means that matter is anything that has inertia and requires a force to get it moving or stopped. Observations vs. Interpretations Observations: The use of all of the senses (sight, taste, smell, hearing and touch) to gather information from and about your surroundings. Interpretations: Is an inference based on an observation. Brings meaning to an observation. 2 types: 1. Qualitative information is non-numerical information. Things that you see. 2. Quantitative information is numerical information. Written in tabular format. For example! Observation Qualitative Description Quantitative Description Your Height Tall, short 180 cm Your Weight Thin, heavy 125 kg The three common states of matter are: Temperature and pressure affect which state the matter is in. Solid! Liquid! The fourth state of matter is called PLASMA. Plasma has all the properties of a gas except that it is composed of charged particles. They exist on stars (the sun), in nuclear explosions, and in neon signs. Gas! 1

2 Solids! Liquids! Generally rigid. Take the shape of the container. Particles are closely packed into a given volume in a highly organized and rigid manner. Particles remain in close contact with each other, but have sufficient room to slide past one another easily. Requires particles to be in direct contact with one another. Do not have an organized packing. Have their own shapes. Not compressible. Not compressible. Their volumes only change slightly in response to changes in temperature and pressure. Their volume changes very little in response to temperature and pressure changes. Gasses! Particle Movement Completely fill a container. The particles are widely separated and only contact each other during collisions. Particles in the three phases can exhibit three types of movement: Vibrational: Vibration of the particle. Very compressible. Their volume is drastically changed by temperature and pressure. Rotational: Spinning of the particle. Translational: Movement of the particle in a straight line. Solids: Vibratonal movement only. A quick note on energy! Liquids: Vibrational, rotational, and translational motion. Gasses: Translational movement only. As we increase the average kinetic energy (temperature) of the particles, the matter changes to a higher energy phase. 2

3 Chemical and Physical Changes Chemical Change: A change in which new substances are formed. Produces a set of chemicals which is different from the set of chemicals which existed before the change. Reactants! Products! Examples include: Noticeable heat or light is produced. A colour change is observed. One of the original materials is used up. Bubbles of gas may appear, which shows that a new gas may be forming. Cloudiness may result; this shows that a solid is forming (a precipitate). Physical Change: NOTE: A change in the phase of a substance, such that no new substances are formed. A physical change does not change the set of chemicals involved. ICE! WATER! Chemical changes are often accompanied by physical changes. Physical Property! Extensive: Any aspect of an object or substance that can be measured or perceived without changing its identity. Can be either: Intensive: A physical property which depends on the amount of the substance present. Examples: Mass, volume, length, energy. A physical property which depends solely on the nature of the substance, NOT the amount of substance present. Used to identify a substance. Examples: Density, melting temperature, viscosity. 3

4 Perceptions! Huh? Certain perceptions are often described (or even "measured") as if they are intensive or extensive physical properties. In fact, perceptions are fundamentally different from physical properties. They are based on an observers response. Examples of perceptions related to an intensive physical property: Temperature: in this case all observers will agree which is the hotter of two objects. Examples of perceptions related to an extensive physical property: Color of a solution: The related physical property is the transmission or absorption spectrum. Homework The Kinetic Molecular Theory Do: W.S. 2-3 The Kinetic Molecular Theory explains the forces between molecules and the energy that they possess. Energy: Anything that is not matter and can cause a change in matter. During and energy conversion, there no loss or gain of energy. The forms of energy change constantly, but the amount of energy remains constant. Potential Energy: Energy stored within a physical system. It has the potential to be converted to different forms of energy, and to do work in the process. Kinetic Energy: The energy an object posses due to its motion. Changes in State By heating or cooling matter, we can change the state in which it is in. Transitions between phases are called CHANGES IN STATE. Where: m = mass v = velocity There are several temperature points where significant changes to matter take place. 4

5 Melting Temperature The temperature where a solid changes to a liquid. Boiling Temperature The temperature where a liquid changes to a gas Freezing Temperature The temperature where a liquid changes to a solid. At the MELTING/FREEZING TEMPERATURE, the solid and liquid phases co exist. Condensation Temperature The temperature where a gas changes to a liquid. At the BOILING/CONDENSATRION TEMPERATURE, the liquid and gas phases co exist. The temperature does not change during a phase change (such as melting and boiling).! Another way to look at this relationship: In general, continued heating of a solid produces the following temperature behavior: Your lab write-up Labs are to be done in a coiled book. Leave space before and after your data for the lab writeup. All labs are written in BLUE or BLACK ink. Underlining is done in RED. Numeric calculations in the Analysis/Questions section may be done in PENCIL. 5

6 What should it look like? Homework Do: Heating Curves and Stuff W.S. Read: Freezing and Melting of Water Lab What is on the exam? What is on the exam? Lab safety Matter and It s Phases Hazardous Household Product Symbols WHMIS Classes Solids, Liquids, and Gasses The Kinetic Molecular Theory Changes in state Symbols Definitions MSDS Sheets Heating Curves PPE s 6