Download Chemsitry Test Review

SCIENCE TEST (PRACTICE based on class questions) Fact: Absolute zero refers to a new state of matter achieved at a temperature of -­‐273 degrees Celsius at which all motion ceases to exist. Questions: 1) Explain what absolute zero is. Restate the fact above for a complete answer 2) Theoretically, what is the coldest temperature that can be reached? Answer: -­‐
273 degrees C 3) What is coldness? Answer: coldness is the absence of heat just like darkness is the absence of light. Therefore, there is a maximum coldness (or darkness) in this sense. Fact: One average tree outputs about 10 L of oxygen each day Questions: 1) How much oxygen does the average tree output per year? Answer: If a tree outputs 10 L of oxygen per day, and there 365 days per year, the total output of oxygen per year is 10 L / day x 365 days = 3650 L of oxygen. 2) How much Pepsi does a tree output? Answer: 0 L Fact: What is the difference between an element, compound, and a mixture? Questions: Break it down – Element: the simplest form of a pure substance. Compound: two or more elements combined together. Mixture: two or more substances to form a mixture (homogenous or heterogeneous) Fact: The Earth is a closed system, which means that atmospheric gases (i.e., green house gases) cannot flow into outer space because there is no atmosphere. Secondly, this means that the more we pollute, the more we are stuck with it because it cannot leave. Questions: 1) Why is Earth considered a closed system? 2) Why is this a problem? Fact: Non-­‐point source pollution, when added together, is worse than point source pollution. A point source of pollution is called “point source” because you can see it and feel it directly and spot it out and point at it as a source for pollution. So obviously, a “non-­‐point source pollution” refers to pollution that you may not be able to spot or point out because it is too small to notice. Questions: 1) Is an electric car itself a nonpoint or point source of pollution? Answer: NEITHER. It doesn’t pollute at all. 2) Are smokers nonpoint or point sources of pollution? Answer: Generally, as you can’t see smokers from a distance, they are considered nonpoint sources of pollution. Fact: A solid iron cannot catch on fire but it does distribute heat across its own body. Fact: For a fire to continue, it needs to burn oxygen and needs surface area. So for a piece of iron in strands with space in between (consisting of air and oxygen), fire can burn those thin strands and eventually eat the iron away and produce a nice fireworks show at the same time. Questions: 1) Why does a large solid piece of iron not catch on fire but a scrubber (made of a mesh of thin iron wires) does catch on fire? Fact: Scientists classify matter based on its composition. Questions: 1) Why is it not a good idea to classify matter based on its phases or states? Story: From the macrocosm to the microcosm, the quest for finding the smallest thing that exists (if it exists), describe the journey we discussed this in class.