AP MCQ 04ABCDEF PART 1 Questions 01-03: An experiment is conducted in order to determine the mass of silver metal in an alloy. The alloy is dissolved in acid to convert all of the silver metal to silver ions, and those ions are then precipitated by reaction with excess sodium chloride. The precipitate is washed, dried and weighed, and the following data are collected. Mass of silver alloy = 4.3148 g Mass of filter paper = 0.50000 g Mass of filter paper and dried precipitate 1.9332 g Question 01: Identify the precipitate and the number of moles of it produced in the gravimetric analysis? NaCl; 0.010000 mols NaCl; 1.4332 mols AgCl; 1.4332 mols AgCl; 0.010000 mols Question 02: What is the % by mass of silver in the alloy? 0.010000 % 1.0787 % 25.000 % 100.00 % Question 03: At the end of the experiment it is found that the actual (real) % of silver in the alloy is lower than the % calculated from the experimental data. Which of the following is the most likely explanation for the difference between the actual (real) value, and the calculated value? Sodium ions were precipitated Some of the precipitate fell off the filter paper before weighing The precipitate was not completely dried The precipitate decomposed during drying, releasing a gas Question 04: The complete combustion of one mole of a hydrocarbon in oxygen, yields carbon dioxide and water in a molar ratio of 3CO2 : 4H2O. What is a possible formula for the hydrocarbon? CH4 C3H4 C3H8 C4H4 Questions 06-07: When 2.299 g of sodium are brought together with 2.000 g of fluorine and the reaction below occurs. 2Na(s) + F2(g) → 2NaF(s) Question 05: What is the maximum mass of sodium fluoride that can be produced? 2.000 g 2.229 g 4.199 g 4.299 g Question 06: When the reaction is repeated, this time introducing 1.000 mole of Na metal with 0.5000 moles of F2 gas, it is found that 21.00 g of NaF are produced. What is the percentage yield in this experiment? 25.00 % 50.00 % 75.00 % 100.0 % Question 07: Consider the combustion of ammonia shown in the equation below. Which of the following statements is true in relation to this reaction? 4NH3 + 5O2 ⇒ 4NO + 6H2O Reacting 4 moles of ammonia with 6 moles of oxygen will yield more products than reacting 4 moles of ammonia with 5 moles of oxygen Reacting 4 moles of ammonia with 6 moles of oxygen will result in ammonia being left over at the end of the reaction Reacting 4 moles of ammonia with 6 moles of oxygen will produce a total of 10 moles of products Reacting 4 moles of ammonia with 6 moles of oxygen will result in no reaction taking place, since the ratio must be 4:5 Question 08: A 100. mL sample of 0.100 M Li2CO3 solution is poured into a beaker that contains to 50.0 mL of 0.300 M Ba(NO3)2 solution. A precipitate is observed. Which of the following correctly predicts the contents of the beaker at the end of the reaction? The precipitate is LiNO3 and excess barium ions are left in solution The precipitate is BaCO3 and excess barium ions are left in solution The precipitate is LiNO3 and excess carbonate ions are left in solution The precipitate is BaCO3 and excess carbonate ions are left in solution Question 09: What type of interaction (force or bond) is changed when solid magnesium chloride is melted? London dispersion force Ionic bond Dipole-dipole force Covalent bond Question 10: Chemical changes always involve the breaking of which type of interaction (force or bond)? London dispersion forces Ionic or covalent Dipole-dipole force Hydrogen bonds Question 11: How might one recognize a change as being purely a physical one? Only intermolecular forces are broken Either ionic or covalent bonds are broken Only ionic bonds are broken Only covalent bonds are broken Question 12: What type of change takes place when solid sodium chloride is dissolved in distilled water? Only a physical change since only IMF's are broken Only a chemical change since only ionic bonds are broken Both chemical & physical since both intra and inter interactions are broken More data are needed to answer this question Δ
