Thought Work -- Heat & Gas Laws

 1.   Devise a way to remove carbon dioxide (carbonation) from soda pop. This must be done quantitatively. How does temperature affect the solubility of gases being dissolved in liquids under pressure?

 2.   Explain what happens to a marshmallow when it is toasted. Why does this happen? What would happen to a frozen marshmallow? Why does a marshmallow float?

 3.   Find the pressure you exert when standing on both feet, on one foot, and lying flat on your back.

 4.   Explain why a toy balloon filled with hydrogen partially deflates overnight.

 5.   Using a steel ball and pieces of old pottery or modeling clay, devise an experiment that would demonstrate potential energy, kinetic energy, and momentum (all of which are involved with mass and velocity).

 6.   Suppose you had two identical sections of glass plate before you, one heated above body temperature and the other cooled by ice. What happens when you breathe on the two of them and why? Maybe try this at home first.

 7.   Devise an experiment to show the concept of diffusion, another to show cohesion, adhesion, and surface tension, and one to show buoyancy and Pascal's Law.

 8.   Changing ice to water requires 80 calories per gram of ice, but changing water to steam requires about 540 calories per gram of water. What does this tell you about the intermolecular forces in ice and water, both qualitatively and quantitatively? Also explain why the chemical change of splitting or forming water requires about 5 times as many calories as the physical change of state.

   Chemical Properties of Matter

 Chemical properties are those properties of a substance that can be determined by a chemical test. Chemical properties are seen by the material's tendency to change, either alone or by interaction with other substances, and in doing so form different materials.

 1.does the substance support combustion: examples are O₂ and Cl₂

2. does the substance burn (combustibility)

3. how does the substance react with acids (does it dissolve, evolve gases, explode, do nothing)

4. how does the substance react with oxygen (burn, form new compounds)

5. what is its reaction with electricity (usually it will be separated into simpler components)

 examples: alcohol burns, iron rust, wood decays, sodium explodes in water

 

Physical Properties of matter

 Physical properties are those properties used in identifying substances when we use our senses. These do not require chemical analysis.

 1.   color - reaction of eye and brain in recognizing combinations of certain wavelengths of visible light.

 2.   hardness - a measure of the ability of a substance to resist abrasion (see Mows Scale of Hardness)

 3.   density - the mass divided by its volume (often reported as specific gravity which is a unitless relationship between the density of the substance and the density of water)

 4.   texture - how object feels to touch; usually rough or smooth

 5.   magnetic attraction -  is the material attracted to a magnet or can it be magnetized (must contain Fe, Co. Ni, or steel)

 6.   solubility -  the amount of a substance which will dissolve in a known amount of solvent at a given temperature

 7.   taste -  reaction of taste buds to stimuli along with the brain's recognition of the pattern

 8.   light transmission -  is the substance transparent, translucent, or opaque

 9.   viscosity - a measure of the internal resistance (friction) to flow in a liquid (molasses and tar would have high viscosities)

 10. refractive index   amount a ray of light is bent as it passes through a substance (technically the ratio of the speed of light in that substance to the speed of light in a vacuum)

11. specific heat capacity  -   the amount of heat energy (calories or Joules) required to change the temperature of 1 gram of a substance by 1 °C

 12. atomic radius -  the distance from the center of an atom's nucleus to the outermost orbital electron

 13. boiling point  -   the temperature at which the liquid's vapor pressure equals atmospheric pressure during the boiling of a pure substance the temperature remains constant as long as both liquid and vapor are present

 14. melting-freezing point  -   temperature at which solid-liquid phase is in equilibrium - during melting of pure solid the temperature remains constant; when all solid is melted and only liquid is present, further heating results in a steady increase in temperature to the boiling point

 15. odor -  olfactory nerves are stimulated by certain molecule and send messages to the brain which remembers the pattern

 16. expansion - contraction coefficients -   materials expand or contract a known amount when heated or cooled