1) Two flexible containers for gasses are the same temperature and pressure. One holds .50 grams hydrgen and the other 8.0 grams of oxygen. Which of the following statements regarding these gas samples is false?
b) the number of molecules in the hydrogen container is the same as the number of molecules in the oxygen container
c) the density of the hydrogen sample is less than that of the oxygen sample
d) the average kinetic energy of the hydrogen molecules is the same as the average kinetic energy of the oxygen molecules
e) the average speed of the hydrogen molecules is the same as the average speed of the oxygen molecules
2) Pi bonding occurs in each the following species except
3) The reaction of silver metal and dilute nitric acid proceeds according to the equation above. If 0.10 mole of powdered silver is added to 10 ml of 6.0 molar nitric acid, the number of moles of NO gas that can be formed is?
3Ag(s) + 4HNOsub3 -->/<---- 3AgNOsub3 + NO(g) + 2 Hsub2O
1) The answer is (e) because avarage speed of hydrogen is greater than the avarage speed of oxygen.
The answers are given with short explanations.
Asteroid Physics Problems
1. As mentioned before, our asteroid is in the shape of a sphere and has a mass of 1000 kilograms. Determine the density (in grams per cubic centimeter) of this asteroid if its diameter is known to be 1.0 meters. Useful information: 1 kg = 1000 g, 1 m = 100 cm, volume of sphere = 4/3 p r3. Remember that the radius of a sphere is equal to half its diameter! Show all of your work.
2. How does your calculated density (in grams per cubic centimeter) compare to the density of water? Would you expect this asteroid to float or sink in water based on your calculations?
3. One side of our asteroid is constantly illuminated by the Sun while the other side remains in the dark. Do you expect there to be a temperature difference between the light and dark sides? Explain why or why not. If the two sides are at different temperatures, how might heat transfer from one side to the other? Note that our asteroid does not have enough gravity to hold an atmosphere.
4. Occasionally an asteroid will break into fragments due to a collision. These fragments can leave the asteroid belt and some even make their way to Earth. Upon entering the Earth's atmosphere, a fragment is heated to high temperature by frictional forces. What would happen to any water-ice contained within a fragment? Is this type of change considered a chemical change or a physical change? Is this an endothermic or exothermic change? Explain.
5. Asteroids are mainly composed of metals like iron and nonmetals like carbon. Briefly explain the differences between metals and nonmetals based on your knowledge of the periodic table.
6. If the asteroid fragment contains carbon, it may burn when entering the Earth's atmosphere. What is the most likely compound to result from this process? Which type of chemical bond would result from this process? Of the two broad classes of chemical reactions mentioned in this course, which type would this be? Be sure to fully explain all of your answers.View Full Posting Details