NSCI 100 NSCI100 Quiz 4 with Answers (UMUC)
NSCI 100 NSCI100 Quiz 4
- A friend argues that if mass were really conserved he would never need to refill his gas tank. What explanation do you offer your friend?
- What is a chemical reaction?
- What is a chemical equation?
- Given the following generic chemical reaction, which is the product? - X → Y
- For the following balanced reaction, which of the following is a solid? - 2 Na(l) + Cl2(g) → 2 NaCl(s)
- For the following balanced reaction, which of the following is a gas? - 2 Na(l) + Cl2(g) → 2 NaCl(s)
- Why is it important for a chemist to know the relative masses of atoms?
- How does formula mass differ from atomic mass?
- The relative mass of carbon is 3/8 that of an oxygen molecule. How many grams of carbon are needed to have the same number of particles as found in 32 grams of oxygen molecules?
- Which has the greatest number of molecules?
- How many grams of gallium are there in a 145 gram sample of gallium arenside, GaAs?
- What is a reaction rate?
- Why might increasing the temperature alter the rate of a chemical reaction?
- What is the activation energy?
- The yeast in bread dough feeds on sugar to produce carbon dioxide. Why does the dough rise faster in a warmer area?
- Why does a glowing splint of wood burn only slowly in air, but rapidly in a burst of flames when placed in pure oxygen?
- Why is heat often added to chemical reactions performed in the laboratory?
- Is the synthesis of ozone, O3, from oxygen, O2, an example of an exothermic or endothermic reaction?
- Which of the following statements about catalysts is NOT true?
- Which of the following statements accurately describes the action of ozone?
- What is the environmentally unfriendly component of chlorinated fluorocarbons that ultimately damages ozone?
- What is the main difficulty in trying to eliminate chlorinated fluorocarbons from the atmosphere?
- The chlorinated fluorocarbons molecules are acting as a(n) ________ by converting hundreds of thousands of molecules before they are inactivated.
- How is ozone produced in the upper atmosphere?
- A catalytic converter increases the amount of carbon dioxide emitted by an automobile. Is this good news or bad news?
- What is an exothermic reaction?
- What is an endothermic reaction?
- If it takes energy to break bonds and you gain energy in the formation of bonds, how can some reactions be exothermic while others are endothermic?
- How many bonds between nitrogen and hydrogen are formed if you react nitrogen with hydrogen according to the following reaction? - N2 + 3H2 → 2 NH3
- Given that the bond energy of N2 is 946 kJ/mole, the bond energy of O2 is 498 kJ/mole and the NO bond energy is 631 kJ/mole, how much energy is required to react 1 mole of nitrogen molecules according to the following reaction? - N2 + O2 → 2 NO
- Which of the following reaction energies is the least exothermic (but still an exothermic reaction)?
- Which of the following reaction energies is the most endothermic?
- Which is higher in an endothermic reaction: the potential energy of the reactants or the potential energy of the products?
- Bond energies increase in going from C-N (lowest) to C-O to C-F (highest). Explain this trend based upon the atomic sizes of these atoms as deduced from their positions in the periodic table.
- Wild plants readily grow all by themselves yet the molecules of the growing plant have less entropy than the materials used to make the plant. How is it possible for a there to be this decrease in entropy for a process that occurs all by itself?
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