Homework

Objective Two

1. The difference between physical and chemical changes is that physical changes are changes on the outside, such as change of shape or state (solid, liquid, gas, plasma) whilst chemical changes happen when the molecules changed.  A physical change would be cutting down a tree or melting ice.  An example of a chemical change is rust.

2. There are four signs of a chemical change.  One is gas emitting or the substance bubbling. Change of color (colour, if your British) also shows that a chemical change has occurred.  The final two are a solid being formed or light, heat, or sound being created. (http://wiki.answers.com/Q/Four_ways_you_can_tell_a_chemical_change_has_taken_place)

3. The  Law of Conservation of Mass states that matter can neither be created or destroyed.  (And that’s why we had to do all that chemical balancing.)  This was discovered by our good friend, Antoine Lavosier (who didn’t quite get to be the father of the periodic table, but he made up for it.)

4. Temperature is the average kinetic energy, but thermal energy is the total energy of particles. (http://www.bristolaggie.mec.edu/school/Velozo/Chapter6.htm)

5. An example of an endothermic reaction is something like photosynthesis.  An example of an exothermic reaction is the combining of chlorine and sodium to create table salt.  (http://chemistry.about.com/cs/generalchemistry/a/aa051903a.htm)

Objective Three

1. One of the forms of energy is chemical energy.  When humans digest foods, the chemical bonds are broken down.  The energy from that good goes into the human, in a different form.  Thermal energy can cause substances to melt.

2. A rolling bowling ball has kinetic energy.

3. A bowling ball sitting still has potential energy.

4. Electromagnetic energy is one type of energy that is often unseen.  It is found in gamma rays and radio waves.  It is can be defined as “the energy source required to transmit information (in the form of waves) from one place to another.”  (http://www.buzzle.com/articles/what-is-electromagnetic-energy.html)

5. The energy of electrons moving from one place to another is electrical energy.  This energy is found static electricity and lightning.

Objective Five

1. The relationship described in Boyle’s Law is the relationship between volume and pressure.  When volume increases, pressure decreases, but when pressure increases, volume decreases.

2. Scientists only half-fill high-altitude balloons because as the balloon travels upward, the pressure on the balloon decreases so the balloon gets bigger

3. PV=K  (pressure times volume equals constant)

4. Boyle’s Law is used by physicians when talking about lungs.  As the diaphragm lowers, the lungs grow bigger because of less pressure.  The diaphragm then applies pressure and carbon dioxide leaves the body because the volume of the lungs decreases.

5. SCUBA divers rely on Boyle’s Law because pressure increases and decreases due to the distance they are underwater.  As the pressure goes up, SCUBA divers use the air faster than at a lighter pressure.

Objective Six

1. Charles’s Law states that volume and temperature have an inverse relationship.  When volume increases, temperature increases.  When volume decreases, temperature decreases.

2. As the temperature of a gas increases, the gas molecules move more quickly.

3. Jacques Charles and Nicolas Robert were the first people to fly in a hydrogen balloon.

4. The balloon fell into a field and was torn to shreds by terrified peasants.

5. Pressure cannot be changed.