Chemistry Released Items 2001

Evaporate and then distill Evaporate and then condense 1. To remove the sand first then the salt from a mixture of sand and salt water, one combination of techniques you could use would be the first-- Evaporate and then distill Evaporate and then condense Filter and then evaporate Filter and then condense 1 2 3 4 5

2. Which is an example of a synthesis reaction? HCl + KOH→KCl + H20 Pb(NO3)2 + 2HBr→PbBr2 + 2HNO3 C + O2→ CO2 Mg + H2SO4 → MgSO4 + H2 1 2 3 4 5

3. What would be the product(s) of this reaction? 3MgO + 2Al → 2Mg3Al2O3 Mg3Al2 + 3O2 6Mg + Al3O2 3Mg + Al2O3 1 2 3 4 5

4. One of the main assumptions of the kinetic molecular theory of gases is that the particles of an ideal gas-- Must be single atoms instead of molecules Are in constant motion Must be maintained at very high pressures Must be highly chemically reactive 1 2 3 4 5

Which is the correct formula for iron(III) sulfate? Fe3(S04)2 FeSO4 Fe2(SO4)3 Fe2(SO3)3 1 2 3 4 5

6. Which of these represents the empirical formula and the molecular formula, respectively, for a given organic compound? CH and C2H2 CH and CH4 CH2 and C2H2 CH3 and C3H12 1 2 3 4 5

Specific Heat Capacities of Some Common Substances What probably causes water to have the highest specific heat of the substances listed above? Molecule size Molecular mass Strong hydrogen bonds High density of ice Substance Specific Heat Capacity (cal/g * °C) Aluminum 0.21 Alcohol 0.58 Water 1.00 Wood 0.42 1 2 3 4 5

8. Each beaker shown above contains 2 8. Each beaker shown above contains 2.2 grams of iron and 1 liter of 3M H2SO4 at STP. Which reaction will go to completion first and why? Beaker A because of increased surface area Beaker B because of increased surface area Beaker A because of a higher concentration level Beaker B because of a higher concentration level. 1 2 3 4 5

The element chlorine exists as two naturally occurring isotopes The element chlorine exists as two naturally occurring isotopes. Cl-35 occurs 75% of the time and Cl-37 occurs 25% of the time. Which of the following calculations should be used to calculate the correct average atomic mass of chlorine? A B C D 1 2 3 4 5

10. The average kinetic energy of a sample of water molecules is__ Increased as the temperature is decreased. Increased as the temperature is increased Unaffected by temperature changes Always equal to zero 1 2 3 4 5

11. Electronegativity differences are often helpful in determining the bond character between two atoms. A general rule states t hat if the electronegativity difference between two atoms is greater than 1.67, an ionic bond would most likely be formed. Using the chart above, which pair of atoms would probably form the strongest ionic bond? Al-P Na-Cl K-F Ca-O 1 2 3 4 5

12. The mass of an object was recorded as 9. 93g, 9. 90g, and 10 12. The mass of an object was recorded as 9.93g, 9.90g, and 10.02 using an electronic analytical balance. What is the average of these three masses expressed to the correct number of significant figures? 9.9g 9.95g 10.0g 10.00g 1 2 3 4 5

13. Radioactive iodine-131 has a half-life of eight days 13. Radioactive iodine-131 has a half-life of eight days. The amount of a 200.0 gram sample left after 32 days would be--- 6.25g 12.5g 25.0g 50.0g 1 2 3 4 5

2H2S(g) + 3O2(g)→2H2O(g) + 2SO2(g) If 3 2H2S(g) + 3O2(g)→2H2O(g) + 2SO2(g) If 3.50 g of H2S are used in the above reaction, what will be the theoretical yield of water in grams? 0.102 g 0.185 g 1.85 g 185 g 1 2 3 4 5

15.Which of these describes a tendency for atomic radii as displayed on the periodic chart? Atomic radii decrease left to right across a period. Atomic radii increase left to right across a period. Atomic radii decrease top to bottom down a group. Atomic radii increase, then decrease from top to bottom down a group. 1 2 3 4 5

16. A student conducted an experiment and was interested in the mass of the product of the chemical reaction. What is the mass of the NaCl? NaHCO3(s) + HCl(aq)→NaCl(aq) + CO2(g) + H2O (g) 0.75g 1.75g 2.25g 2.50g

17. A solution contains 225g of glucose, C6H12O6 dissolved in enough water to make 0.825L of solution. What is the molarity of the solution? 0.66 M 0.97 M 1.03 M 1.52 M 1 2 3 4 5

The water was not completely evaporated from the compound. 18. A student wanted to calculate the formula for hydrated copper sulfate. After careful massing, she heated the compound to remove the water. She calculated the formula to be CuSo4.4H2O. The actual formula was CuSO4.5H2O. What is the most likely source of analytical error in the student’s experiment? The water was not completely evaporated from the compound. The actual mass of the anhydrous CuSo4 was less than the measurement. The CuSO4 reacted with elemental copper. The atmospheric pressure prevented complete reaction. 1 2 3 4 5

19. What is the percentage of aluminum in aluminum oxide (Al2O3)? 47% 48% 53% 54% 1 2 3 4 5

20. Which of these conclusions can be drawn from Rutherford’s experiment? Each atom contains electrons. The nucleus of an atom can be split. Each atom contains protons. Atoms are mostly empty space. 1 2 3 4 5

It has a different number of protons and two less neutrons than C-12. How does the radioactive isotope C-14 differ from its stable counterpart C-12? It has a different number of protons and two less neutrons than C-12. It has the same number of protons and two more electrons than C-12. It has the same number of protons but tow more neutrons than C-12. It has a different number of protons and two more neutrons than C-12. 1 2 3 4 5

22. A compound has 50% sulfur and 50% oxygen 22. A compound has 50% sulfur and 50% oxygen. What is its empirical formula? SO4 S2O4 SO3 SO2 1 2 3 4 5

23. An experiment yielded that above temperature and time information 23. An experiment yielded that above temperature and time information. What is the freezing point of the material in this experiment if the material is a solid at time zero? -25°C 0°C 25°C 50°C 1 2 3 4 5

24. How many milliliters of 2. 00 M H2SO4 are needed to provide 0 24. How many milliliters of 2.00 M H2SO4 are needed to provide 0.250 mole of H2SO4? 125 mL 1.25 X 101 mL 8.00 X 103 mL 8.00 mL 1 2 3 4 5

25. A(s) + B(s)→D(g) + heat The reaction shown above is ___ An endothermic reaction An exothermic reaction A decomposition reaction A double-replacement reaction 1 2 3 4 5

Chlorine forms a 1- ion. How many electrons does a chloride ion have? 16 17 18 1 2 3 4 5

27. According to the data, which of the following represents the average density for sample X using the correct number of significant figures? 1 g/mL 0.8 g/mL 0.81 g/mL 0.821 g/mL 1 2 3 4 5

28. CH4 + 2O2→ CO2 + 2H2O The number of grams of oxygen required for the complete combustion of 4.00 grams of methane (CH4) is ___ 4.00g 8.00g 16.0g 32.0g 1 2 3 4 5

29. Which of the groups below has the electron dot structure shown? Noble gases Halogens Alkali metals Transition elements 1 2 3 4 5

Slowly pour the 5 M acid into water 30. A student must make a 3 M acid solution using a 5 M acid solution. Which of these is the safest way to make the solution? Slowly pour the 5 M acid into water Slowly add water to the 5 M acid solution Mix half the acid with water, then add the remaining water Mix half the water with the acid, then add the remaining acid 1 2 3 4 5

31. Four aqueous solutions and their concentrations are shown in the illustration. Which of the solutions is most likely to be the strongest conductor of electricity? I II III IV 1 2 3 4 5

Decreasing the air pressure Increasing the air pressure 32. Water can be made to boil above its normal boiling point of 100°C by ___ Decreasing the air pressure Increasing the air pressure Increasing the heat being applied Decreasing the volume of the container 1 2 3 4 5

Flush the affected area with water Apply a neutralizing agent 33. What is the first step that should be taken when a caustic chemical gets into a person’s eye? Identify the chemical Call for an ambulance Flush the affected area with water Apply a neutralizing agent 1 2 3 4 5

34. According to the table, which of these probably has the strongest bonds? Hydrogen gas Iron crystals Sodium chloride Water 1 2 3 4 5

Decrease the concentration of SO2 Decrease the concentration of O2 35. In the reaction 2SO2 (g) + O2 (g)↔2SO3 (g), which change would cause the greatest increase in the concentration of SO3? Decrease the concentration of SO2 Decrease the concentration of O2 Increase the concentration of SO2 Increase the concentration of O2 1 2 3 4 5

36. A catalyst accelerates a chemical reaction because the___ Catalyst decreases the number of collisions in a reaction Activation energy of the reaction is lowered in the presence of a catalyst Catalyst decreases the concentration of the reactants Temperature of the reaction increases due to the catalyst 1 2 3 4 5

37. A compound is composed of 58. 8% C, 9. 8% H, and 31 37. A compound is composed of 58.8% C, 9.8% H, and 31.4 % O, and the molar mass is 102 g/mol. What is the molecular formula for this compound? C2H10O3 C5H5O3 C5H10O2 CH3O3 1 2 3 4 5

Which of these shows a volume of 1.25 liters expressed in milliliters? 125 mL 12.5 X 101 mL 1.25 X 102 mL 1.25 X 103 mL 1 2 3 4 5

39. An element has an electron configuration of 1s22s22p63s2 39. An element has an electron configuration of 1s22s22p63s2. Which of these will be in the same group as this element? 1s22s22p6 1s22s22p63s23p64s2 1s22s22p63p1 1s22s22p63s23p6 1 2 3 4 5

40. Very Active Metal + Water→Metal Hydroxide + ? Oxygen Hydrogen Metal oxide Air 1 2 3 4 5

41. Which of these elements is the most chemically active? Cl Br I 1 2 3 4 5

42. If the heat of fusion of water is 3 42. If the heat of fusion of water is 3.4 X 102 J/g, the amount of heat energy required to change 15.0 grams of ice at 0°C to 15.0 grams of water at 0°C is ___ 3.4 X 102 J 2.4 X 103 J 5.1 X 103 J 1.0 X 104 J 1 2 3 4 5

Decreases by one-fourth Is doubled Is halved 43. If the pressure exerted on a confined gas is doubled, then the volume of the gas__ Increases four times Decreases by one-fourth Is doubled Is halved 1 2 3 4 5

Activation energy increases Energy of the products increases 44. If the temperature of a reaction is increased, the reaction proceeds at a much quicker rate because the___ Activation energy increases Energy of the products increases Frequency of collisions between reactants increases Energy of the activated complex increases 1 2 3 4 5

45. The formula H2SO4 is representative of which of the following? A catalyst A base An acid An organic compound 1 2 3 4 5

46. Which compound contains both ionic and covalent bonds? NH4Cl MgBr2 CH4 NH3 1 2 3 4 5

Which volume will be occupied by a gas containing 6 Which volume will be occupied by a gas containing 6.02 X 1023 atoms at STP? 1.0 L 11.2 L 22.4 L 44.8 L 1 2 3 4 5

48. Using the chart, which of these combinations will probably form a precipitate? Ammonium chloride Barium bromide Calcium chromate Copper (II) carbonate 1 2 3 4 5

49. A sample of oxygen gas is collected over water at 22°C and 98 49. A sample of oxygen gas is collected over water at 22°C and 98.67 kPa pressure. If the partial pressure of the water is 2.67 kPa, the partial pressure of the oxygen is___ 93.33 kPa 96.00 kPa 98.66 kPa 101.33 kPa 1 2 3 4 5

50. The hydrogen ion concentration is 1 X 10-7 50. The hydrogen ion concentration is 1 X 10-7. What is the pH of this solution? 1 7 10 14 1 2 3 4 5