What is the specific heat capacity of glass?

Calorimetry - foam cup vs glass beaker?

• My understanding is that the foam cup has a lower specific heat capacity and therefore is able to hold more heat than the glass beaker. I'm confused, though, on how this will effect the calorimetry constant... if you were to use the glass beaker instead of the foam cup, would the calorimeter constant be higher or lower? Could someone explain why?

• Answer:

  Pour hot water into a beaker. Place your hand around the beaker to determine if the temperature of the beaker is increasing. Do the same thing with a Styrofoam cup. The beaker will feel warm, because heat energy is flowing from the water, through the glass, and to your hand. The Styrofoam cup will not feel warm. If you place ice water into a glass, water vapor will condense on the outside of the glass. The outside of the glass is much colder than the air. So the water vapor condenses on it. Do the same with a Styrofoam cup, and no water vapor condense on it. The Styrofoam cup will not feel cool. What is the difference? Heat energy flows from a high temperature object to a low temperature object. Temperature measures the average “vibrational and rotational” kinetic energy of the atoms and molecules. See the website below for more information. http://www.physicsclassroom.com/class/thermalP/u18l1c.cfm “A warm cup of water on a countertop may appear to be as still as can be; yet it still has kinetic energy. At the particle level, there are atoms and molecules that are vibrating, rotating and moving through the space of its container. Stick a thermometer in the cup of water and you will see the evidence that the water possesses kinetic energy. The water's temperature, as reflected by the thermometer's reading, is a measure of the average amount of kinetic energy possessed by the water molecules.” “When the temperature of an object increases, the particles that compose the object begin to move faster. They either vibrate more rapidly, rotate with greater frequency or move through space with a greater speed. Increasing the temperature causes an increase in the particle speed. So as a sample of water in a pot is heated, its molecules begin to move with greater speed and this greater speed is reflected by a higher thermometer reading” The 2 paragraphs above are from the website. When the water molecules collide with the molecules of the inner surface of the container, kinetic energy is transferred from the water to the container. This causes the temperature of the inner surface to the container to increase. To determine the amount of energy that will pass through the container, we look at composition and specific heat of the material that the container is composed of. Glass is an amorphous solid, which is mainly composed of SiO2, silicon dioxide. It is a fairly homogeneous material. As one molecule collides with another, the kinetic energy is quickly transferred from the outer surface to the inner surface. The specific heat of glass is approximately 840 J/(kg*˚K) Go to the website below for information about polystyrene. http://en.wikipedia.org/wiki/Polystyrene The long organic molecule does not stay in a straight line. In Styrofoam, the molecules are intertwined and the trap air inside the Styrofoam. You can squeeze the cup and force some of the air out. As the water molecules collide with the polystyrene and air, a variety of types of collisions occur. The kinetic energy does not pass from molecule to molecule in an orderly pattern. This means much more time is required for the temperature of the outside of the cup to be the same as the temperature of the water. The specific heat of polystyrene is approximately 1300 J/(kg*˚K). The specific heat of air is approximately 1000 J/(kg*˚K). Average specific heat = 1150 J/(kg*˚K). Ratio of Styrofoam to glass = 1150/840 = 1.37 This is not a high enough ratio for the Styrofoam cup to not transfer heat energy quickly. This means the disorganized structure and flexible bonds in the Styrofoam is the main cause that makes the Styrofoam cup a much better “insulator” than a glass beaker!