Advanced Placement Chemistry Exam #1 ReTake Part II: Free Response

Transcription

1 Advanced Placement Chemistry Exam #1 ReTake Part II: Free Response 1. Naturally occurring sample of bromine is a mixture of the two isotopes, bromine-79 and bromine-80. a. How many protons, neutrons, and electrons are in a neutral atom of the bromine-80 isotope? b. If the sample of bromine reacts with tin, i. What happens to the number of subatomic particles of each type for the two bromine isotope? ii. What type of bonding will be between tin and bromine? Explain. iii. What could be the names and formulas of the resulting compound? c. If a nonmetal atom (i.e., oxygen) reacts with the bromine isotopes what type of bonding will occur and why? 1

2 2. You discover a new set of polyatomic oxyanions that has the newly discovered halogen element X combined with oxygen. A colleague has already discovered the element X and names it excine. Your analysis shows that the formulas for the polyatomic ions to be XO 4 -, XO 3 -, XO 2 -, XO -. i. What group and family could the element excine most likely belong to? ii. How would you name the polyatomic ions in way consistent with already known and named polyatomic ions? iii. What would be the formulas and names of each associated polyatomic oxyanion when they are acids? iv. What would be the general chemical formulas for salts of Group IA (alkali metals) and IIA (alkali earth metals) and these polyatomic oxyanions of excine when they combine? (Specific elements from each respective group and a polyatomic ion may be used in your answer.) i. Group IA or Group1 (alkali metals) ii. Group IIA or Group 2 (alkali earth metals) 2

3 3. A cylindrical piece of copper metal is in an air-conditioned lab at 19.2 o C. A student using gloves measures its length with vernier calipers at 2.50 cm and it has a diameter of 1.26 cm. The mass of the cylinder is found on an electronic balance to be grams. i. Calculate the biggest and smallest volume of the copper cylinder. ii. Calculate the biggest and smallest density of the copper cylinder. iii. If the true value for the density of copper at 19.2 o C is 8.96 g cm -3, calculate the % error for the answer in part 3(b) using the average density. iv. The cylinder is cut in half with a hacksaw. Explain how this would affect the measurements made, the calculations in part 3(a) and the calculations made in part 3(b)? i. Measurements ii. Part 3(a) iii. Part 3(b) 3

4 v. IF the copper cylinder is removed from a refrigerator where the temperature is 10.4 o C. Explain how would this affect the measurements made, the calculations in part 3(a) and the calculations made in part 3(b) if the cylinder is not allowed to reach room temperature? i. Measurements ii. Part 3(a) iii. Part 3(b) vi. Could the density (volume) of the copper metal be found by water-displacement? Why or why not? 4

5 4. Equation Section Write the formulas to show the reactants and products for ALL of the laboratory situations described below. In all cases a reaction occurs. Assume that solutions are aqueous unless otherwise indicated. Represent substances in solution as ions if the substances are extensively ionized. Omit formulas for any ions or molecules that are unchanged by the reaction. You need to balance the equations, and then answer the followup question about the reaction. a. Solutions of lead (II) nitrate and potassium chloride are mixed in a test tube. i. Who are the spectator ions? b. Equal molar amounts and volumes of sulfuric acid and calcium hydroxide are mixed. ii. Is the resulting solution acidic, basic or neutral? c. Hydrochloric acid is added to granules of magnesium metal. iii. What gas is produced if acetic acid replaces hydrochloric acid? 5

6 You must do one of the following two problems, the other maybe done for extra credit! 5. If a garden hose puts out water at a rate of 65.0 cm -3 per second how many hours will it take to fill an above ground round swimming pool with the following dimensions 15 feet in diameter and 54 inches high? 6. New homeowners have a boulder in their backyard that is almost a perfect cube. The homeowners want to move the rock. They have a lift for 4 tons (or 8,000 lbs), but the truck they own can only carry 2 tons (or 4,000 lbs). Note: lbs = 1 kg. The rock appears to be of uniform composition. The homeowners measure the rock to be 1.89 meters on a side. The homeowner then chips off a small piece of the rock and measures it mass to be grams. The chip is placed into a 100 ml graduated cylinder with 39.8 ml of water. The volume then reads 67.8 ml after the chip is dropped into the graduated cylinder. They need your help at this point to calculate if the truck will be able to carry the boulder. 6