Unit Five- Chemical Quantities Chapter 9: Mole ratios, conversions between chemicals in a balanced reaction (mole, mass), limiting reactant, % yield

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1 Chemistry Midterm Review Exam date: Wednesday, 2/15 during class The midterm exam must be completed before February vacation if you are absent The midterm exam is worth 6% of your year grade and it contains questions from the units below. You cannot replace your score with a cumulative exam score Topics include: Unit One- Matter and Measurement Chapter 2: Properties of matter, Classification, Chemical vs. physical changes Chapter 3: Reading scales, Metric units, Significant Digits, Density Chapter 4: Problem solving techniques, Dimensional analysis Unit Two- Atomic Structure and the Periodic Table Chapter 5: History of atomic models, Atomic structure, Periodic table arrangement, isotopes, ions Sections 7.1 & 7.2: Mole conversions for an element (mass and particles) Chapter 13: Atomic structure, Electron configuration (up to atomic number 20), Lewis dot symbols and valence electrons Chapter 14: Period & Group trends (atomic & ionic radius, ionization energy, electronegativity, reactivity) Section 15.1: Electron configuration of ions Unit Three- Chemical Bonding Ch 6: Types of compounds, properties of compounds, names & formulas of ionic compounds, binary molecular compounds and acids Sections 7.2 & 7.3: Mole conversions of a compound (mass and particles), % composition based on mass, empirical and molecular formulas Chapters 15 &16: Ionic & covalent bonding, Lewis structures, bond polarity, shape & polarity of molecules, attraction between molecules Unit Four- Chemical Reactions Chapter 8: Writing word and formula equations, balancing equations, classifying types of reactions, using solubility rules to identify states of matter, predicting products Section 19.1: Collision Theory, Rates of reactions and factors affecting rates Unit Five- Chemical Quantities Chapter 9: Mole ratios, conversions between chemicals in a balanced reaction (mole, mass), limiting reactant, % yield Unit Six- Gases Chapter 12: Properties of Gases (KMT) and factors affecting gas pressure, gas law (combined and ideal), factors affecting movement of gases, Dalton s law of partial pressure

2 Practice Open Response Questions: Unit One- Matter and Measurement 1. How many significant figures are there in each of these numbers? a m b Mg c ml Classify the following as an element, compound, heterogeneous mixture, homogeneous mixture (solution): b. a. Co (s) b. CO (g) c. NaCl (aq) d. oil + water Unit Two- Atomic Structure and the Periodic Table 2. Define an isotope and an ion. Write the nuclear symbol for two isotopes of potassium and an ion of potassium. 3. Give the charge and location in the atom of each of the following particles: Particle Charge Location in Atom Proton Electron Neutron 4. Fill in the following table: Atom or ion Atomic No. Mass No. # p # e # n Avg. atomic mass Hg 201 K 21 K Fe S 2 30 Uranium Give the electron dot (Lewis) structures for: Ba S 2 K + C 6.Write the electron configuration (1s 2 2s 2 p 6 etc.) of P. 7.Write the electron configuration of potassium. 8.Write the electron configuration of Cl -1.

3 9.On the Periodic Table, identify: a) noble gases b) alkali metals c) halogens d) transition metals e) metalloids f) transuranium elements 10. Define electronegativity. Which elements have the largest electronegativity? the smallest? Why? 11.Which element in Group 1A has the largest atomic radius and why? 12.What element in Period 3 has the largest atomic radius and why? 13.For the same element, rank in order of size, the neutral element, the cation and the anion. Unit Three- Chemical Bonding 14.What is an ionic bond? What is a covalent bond? 15.Write the correct formulas for the following. Include states of matter when possible (assume room temp). a) iron (II) hydroxide b) dihydrogen monoxide c) silver sulfate d) carbon tetrachloride e) ammonium chromate f) potassium sulfide 16.Name the following compounds: a) CrCl 3 b) Mg(NO 3 ) 2 c) Na 2 SO 3 e) PH 3 f) Ba(HCO 3 ) 2 g) AlI 3

4 17. Draw electron dot (Lewis) structures, name the shape, and determine if the molecule is polar. Name Formula Ionic or molecular Lewis dot structure Shape (if molecular) Polarity (if molecular) NH 3 NaI Carbon dioxide 18. a. What molecular compound (covalent bonding) above would experience the greatest attraction between molecules? Lowest attraction? b. Which would have a higher boiling point, H 2 O or CCl 4? Explain your answer. 19. What properties distinguish an ionic solid from a molecular solid? Unit Four: Chemical Reactions 20. Complete and balance the following equations and write states of matter for reactants and products. Label the type of reaction. a. Na + H 2 O b. KClO 3 c. KI + Cl 2 d. AgNO 3 + NaBr e. NaCl + K 2 O 21. Write a chemical equation to show the complete combustion of propane (C 3 H 8 ) 22. Write the chemical equation with states of matter for the reaction between silver nitrate and sodium sulfide. 23. Using your solubility rules, identify whether each of the following compounds are soluble or insoluble in water: a. Na 2 CO 3 b. Pb(NO 3 ) 2 c. Mg 3 (PO 4 ) 2 d. AgCl 24. How does each of the following affect the rate of reaction? a. concentration? b. temperature? c. catalyst?

Unit Five: Chemical Quantities 25. Convert to Moles. a. 25 g of Al 2 (CO 3 ) 3 b. 189 ml CO 2 at STP c. 6.02 x 10 22 atoms of Li 26. Convert to Grams. a. 10. moles of NaOH b. 1.2 L of CO 2 c. 3.00 x 10 24 molecules of O 2 27.

5 Unit Five: Chemical Quantities 25. Convert to Moles. a. 25 g of Al 2 (CO 3 ) 3 b. 189 ml CO 2 at STP c x atoms of Li 26. Convert to Grams. a. 10. moles of NaOH b. 1.2 L of CO 2 c x molecules of O How many moles of hydroxide ions are in 3.5 mol of Ca(OH) 2? 28. Determine the % of Na in NaOH. Show work 29. Determine the empirical formula for a compound composed of 70.0% Fe and 30.0% O. 30. The empirical formula of a compound is CH, its molecular mass is 78. What is its molecular formula? Unit Six: Gases 31. What is STP? Equal moles of H 2 (g) and CO 2 (g) are in a balloon at STP. Which gas molecules are moving faster and why? 32. A popcorn kernel contains a hard outer shell, with a water and starch mixture on the inside. Explain, using kinetic molecular theory, why heating the popcorn kernels causes them to pop. In your answer be sure to explain changes to pressure, volume, temperature as the kernel is popped. 33. A gas occupies 11.2 L at a pressure of 655 kpa and a temperature of 227 C. What will its volume be at STP? 34. If 30 ml of a gas exerts a pressure of 2 atm, what will be the pressure if the volume of the gas is reduced to 20ml? 35. An engineer pumps 5.00 mol of carbon monoxide gas into a cylinder that has a capacity of 20.0 L. What is the pressure in atmospheres of CO inside the cylinder at 25 C? Measurement and Lab 36. How could you test for the presence of oxygen, hydrogen and carbon dioxide? What would the results of the test(s) be? 37. Record the measurements, in cm, indicated by arrows A,B, C &D. A B C D

6 Sample Multiple Choice Problems 1. Which measurement below shows the temperature to the correct precision? a o C b. 26 o C c o C d o C 6. A cylinder is weighed empty and with a liquid. Cylinder with g liquid Cylinder, empty g Volume of liquid 7.0 ml in cylinder What is the density of the liquid? a. 13 g/ml b. 7.4 g/ml c. 5.7 g/ml d. 1.7 g/ml 2. The density of copper is known to be 8.96 g/ml. A student s experimental result shows that the density of her copper cube is 8.79 g/ml. The percent error in this data is. a. 1.93% b % c. 1.90% d. 0.98% 3. Which measurement is written to 4 sig. figs.? a kg b. 3,500 km c m d m 4. Which value is the same as 1.52 x 10-3? a b. 152,000 c d Which property is always conserved during a chemical reaction? a. mass b. volume c. pressure d. solubility 7. Which process is a chemical change? a. the melting of ice b. the burning of a candle c. the magnetizing of steel d. the liquifaction of oxygen 8. Which set consists only of elements? a. Na, Ca, H 2 b. H 3 O +, Cl -, I 3- c. NaCl, CH 4, Br 2 d. H 2 S, CuCl 2, KI 9. How does the average kinetic energy (KE) of hydrogen molecules compare with that of oxygen molecules when both gases are at 25 o C? a. They have equal KE s. b. The KE of hydrogen is ¼ as great. c. The KE of hydrogen is 1/16 as great. d. The KE of hydrogen is 4 times as great. 10. The description of the atom as an entity having most of its mass in a tiny nucleus with electrons moving about in the space of the atom surrounding the nucleus is credited to a. Dalton b. Democritus c. Thomson d. Rutherford

7 11. How many neutrons are present in an atom of silver which has a mass number of 108? a. 14 b. 47 c. 61 d A natural sample of element X consists of about 20% that has an atomic mass of 30 and about 80% with an atomic mass of 31. The mass of element X would be. a amu b amu c amu d amu 13. The electron configuration for magnesium is a. 1s 2 2s 2 3s 3 b. 1s 2 2s 2 2p 2 c. [Ar]2s 2 d. [Ne]3s Element 114 should have properties similar to those of: a. platinum, Pt b. lead, Pb c. astatine, At d. mercury, Hg 15. The name of FeCl 3 is a. iron (III) chloride b. iron chloride c. iron (III) chlorine d. iron trichloride 16. What characteristic of fluorine causes it to be the most active member of the halogen family? a. it forms diatomic molecules. b. it has the smallest atomic radius. c. It has no naturally occurring isotopes. d. It has seven electrons in its outer shell. 17. Which set contains only transition elements? a. Elements 11, 12 and 13 b. Elements 15, 16, 17 c. Elements 26, 27, and 28 d. Elements 48, 49, Which trend is observed as the atomic numbers of Group II, the alkaline earth metals, increase? a. atomic size decreases b. metallic properties decrease c. ionization energy increases d. the tendency to lose electrons increases 19. Which family of elements always forms ions with a charge of -1 in compounds? a. halogens b. transition metals c. alkali metals d. alkaline earth metals 20. Which element of Period 3 has the greatest ionization energy? a. Na b. Al c. P d. Cl 21. Which formula represents and ionic compound? a. NH 3 b. CH 4 c. KI d. Cl 2 O 22. The O-O bond is non-polar, while the H-Cl bond is polar. This is caused by a. the difference in electronegativities b. a metal bonding with a nonmetal c. ionic bonding d. the difference in electron affinities

8 23. What is the correct reading of the thermometer? 27. Which bond is most polar? a. H F b. H Br c. H Cl d. H I 28. Which formula represents a compound that is formed by sharing electrons? a. KCl b. CrCl 3 c. CaCl 2 d. CCl 4 a. 5 o C b. 0.3 o C c. 4.3 o C d. 4 o C 24. Expressed to the correct number of significant figures, the sum of two masses is grams. Which two masses produce this answer? a g g b g g c g g d g g 25. A dry mixture of salt and sand could be separated by a. adding water to the mixture and filtering b. adding water to the mixture and evaporating c. heating the mixture to a high temperature d. cooling the mixture to a low temperature 26. As the atoms in Period 3 of the Periodic Table are considered from left to right, the atoms generally show a. an increase in radius and an increase in ionization energy b. an increase in radius and a decrease in ionization energy c. a decrease in radius and an increase in ionization energy d. a decrease in radius and a decrease in ionization energy 29. What is the total number of valence electrons in a fluorine atom? a. 5 b. 7 c. 2 d What is the total number of neutrons in an atom of Li-7? a. 7 b. 3 c. 10 d Which type of matter is composed of two or more different elements that are chemically combined in a definite ratio? a. a solution b. a compound c. a homogeneous mixture d. a heterogeneous mixture 32. Two basic properties of the gas phase are a. definite shape, definite volume b. definite shape, indefinite volume c. indefinite shape, definite volume d. indefinite shape, indefinite volume 33. Which of the following is the correct electron dot diagram for water? 34. Which of the following is the correct electron dot diagram for carbon dioxide?

35. Which element has the electron configuration below? 42. Which Lewis dot diagram below is incorrect? a. V b. Ca c. P d. As e. Se 39. Which of the following is the electron configuration of O -2?

9 35. Which element has the electron configuration below? 42. Which Lewis dot diagram below is incorrect? a. V b. Ca c. P d. As e. Se 39. Which of the following is the electron configuration of O -2? 40. Which Lewis dot notation for atoms and ion is is correct for the reaction of the formation of calcium phosphide from calcium and phosphorus? 41. How many unshared pairs of electrons are around the central nitrogen atom in a Lewis dot diagram of NH3? a. one b. two c. three d. four 43. The ability of carbon to attract electrons is a. greater than that of nitrogen, but less than that of oxygen b. less than that of nitrogen, but greater than that of oxygen c. greater than that of nitrogen and oxygen d. less than that of nitrogen and oxygen 44. Which statement best describes the substance that results when electrons are transferred from a metal to a nonmetal? a. it contains ionic bonds and has a low melting point b. it contains ionic bonds and has a high melting point c. it contains covalent bonds and has a low melting point d. it contains covalent bonds and has a high melting point

10 45. Which statement explains why the radius of a lithium atom is larger than the radius of a lithium ion? a. Metals lose electrons when forming an ion. b. Metals gain electrons when forming an ion. c. Nonmetals lose electrons when forming an ion. d. Nonmetals gain electrons when forming an ion. 46. The atoms of the elements in Group II, have the same a. mass number b. atomic number c. number of protons d. number of valence electrons 47. Which element has the highest electrical conductivity? a. Mg b. He c. H d. Cl 48. The number of significant digits in is a. 7 b. 4 c. 5 d is equal to a. 430 b c d x = a. 162 b. 163 c d. none of these 51. Which of the following can be separated only by chemical means? a. elements b. compounds c. homogenous mixtures d. b and c only e. a and b only 52. Which of the following is a chemical change? a. evaporation of water b. distillation of water c. freezing of water d. forming hydrogen and oxygen from water 53. The statement which describes a physical property of the element oxygen is a. oxygen supports the burning of paper b. oxygen is needed for the rusting of iron c. oxygen must be present for food to decay d. oxygen has a density of 1.43 grams per liter e. oxygen is a component of water 54. Only a physical change takes place in a. producing water by burning hydrogen in air b. breaking water into its elements by an electric current (electrolysis) c. change water into ice by lowering its temperature 55. Three different observers measure the melting temperature of a substance and agree on the same value, but the value they obtain does not agree with the accepted value. Their measurements can be described as a. both accurate and precise b. precise, but not accurate c. neither accurate nor precise d. accurate but not precise

11 56. In general, when elements combine chemically to form compounds a. they retain all their original properties b. a mixture results c. new substances with new and different properties are formed d. solutions are formed 57. What is the mass number of an ion of potassium, K+, with 18 electrons, 19 protons and 20 neutrons? a. 36 b. 37 c. 38 d What is the total number of atoms contained in 2.00 moles of nickel? a b. 118 c x d x What is the formula for aluminum acetate? a. AlC 2 H 3 O 2 b. Al3C 2 H 3 O 2 c. AlC 6 H 9 O 6 d. Al(C 2 H 3 O 2 ) Given the unbalanced equation: Al + O 2 Al 2 O 3 When this equation is completely balanced using the smallest whole numbers, what is the sum of the coefficients? a. 9 b. 7 c. 5 d What is the empirical formula of the compound whose molecular formula is P 4 O 10? a. PO b. PO 2 c. P 2 O 5 d. P 8 O What is the molar mass of K 2 CO 3? a. 138 g b. 106 g c. 99 g d. 67 g 63. What is the percent by mass of oxygen in magnesium oxide, MgO? a. 20% b. 40% c. 50% d. 60% 64. A compound is 86% carbon and 14% hydrogen by mass. What is the empirical formula for this compound? a. CH b. CH 2 c. CH 3 d. CH What is the mass in grams of 3.0 x molecules of CO 2? a. 22 g b. 44 g c. 66 g d. 88 g 66. What is the percent by mass of water in the hydrate Na 2 CO 3 * 10H 2 O (formula mass = 286)? a. 6.89% b. 14.5% c. 26.1% d. 62.9% 1) All of the following are physical changes except: a. water boiling b. natural gas burning c. table salt dissolving d. melting silver 2) Which statement is true about the law of conservation of mass as applicable to a chemical reaction? a. Energy is not created nor destroyed. b. Mass can be destroyed through the evolution of a gas. c. The number of molecules of reactants equals the number of molecules of products. d. The mass of reactants must equal the mass of the products.

12 3) Elements on the right side of the periodic table become more active as we move a. downward because the atoms get larger b. downward because the atoms get smaller c. upward because the atoms get larger d. upward because the atoms get smaller 4) Al 3+ is caused by a. a gain of 3 protons by Al b. a gain of 3 electrons by Al c. the sharing of 3 electrons by Al d. the loss of 3 electrons by Al 11) In which of the following is the number of neutrons correctly computed? a. C-13 has 13 neutrons b. N-15 has 7 neutrons c. O-18 has 10 neutrons d. Zn-70 has 100 neutrons 12) Which of the following elements would react most similar to chlorine? a. sulfur b. argon c. carbon d. bromine 5) The element with the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 3 is a. Al c. Si b. Mg d. P 6) The electron configuration for the Na + ion is c. gains electrons and becomes negatively a. 1s 2 2s 2 2p 6 3s 1 3p 3 c. 1s 2 2s 2 2p 6 charged. b. 1s 2 2s 2 2p 6 3s 1 d. 1s 2 2s 2 2p 6 3s 2 d. loses protons and becomes negatively 7) What is the mass of a solid whose density is 5.60 g/cm 3 and volume is 10.0 cm 3? a g b g c g d g 8) Isotopes of an element differ in their number of: a. neutrons b. protons c. electrons d. electron shells 9) A neutral atom with atomic number 16 and mass number 34 contains: a. 16 protons, 18 neutrons and 16 electrons b. 16 protons, 34 neutrons and 16 electrons c. 34 protons, 16 neutrons and 16 electrons d. 16 protons, 16 neutrons and 18 electrons 13) When an atom forms a cation, it: a. gains protons and becomes positively charged. b. loses electrons and becomes positively charged. charged. 14) In which list are the charges of each ion shown correctly? a. Li +,Na 2+,K 3+ b. Na +,Mg 2+,Al 3+ c. N 3+,O 2+,F + d. N -,O 2-,F 3-15) Which of the following is a molecular compound? a. NaCl b. MgSO 4 c. N 2 O d. Al 2 O 3 16) What is the formula for ammonium sulfate? a. NH 4 S b. NH 4 SO 4 c. (NH 4 ) 2 SO 4 d. NH 4 (SO 4 ) 2 10) Which of the following lists the element, number of protons and number of electrons correctly? a. H, 1 proton, 1 electron b. He, 2 protons, 4 electrons c. C, 6 protons, 12 electrons d. Ne, 10 protons, electrons 17) Which of the following has the correct formula for the name given? a. PbCO 3, lead (II) carbonate b. Fe 2 O 3, iron (II) oxide c. PCl 3, phosphorous chloride d. Li 2 S, dilithium monosulifde

13 18) What is the name for P 4 O 10? a. phosphorous oxide b. tetraphosphorous decaoxygen c. tetraphosphorous decaoxide d. phosphorous decaoxide 19) What are the coefficients, listed in order, of the following reaction when it is properly balanced? C 3 H 6(g) + O 2(g) CO (g) + H 2 O (g) a. 1,3,3,3 b. 3,2,1,2 c. 9,2,2,3 d. 1,2,3,3 20) What are the coefficients, listed in order, of the following reaction when it is properly balanced? F 2(g) + Al 2 O 3(aq) AlF 3(aq) + O 2(g) a. 3,1,2,2 b. 1,1,2,3 c. 2,2,4,3 d. 6,2,4,3 21) The reaction below is an example of: F 2(g) + Al 2 O 3(aq) AlF 3(aq) + O 2(g) a. combination b. single-replacement c. decomposition d. double-replacement 22) What are the coefficients, listed in order, of the following reaction when it is properly balanced? hydrochloric acid + magnesium hydroxide magnesium chloride + water a. 1,1,1,1 b. 2,1,1,2 c. 1,2,2,1 d. 1,2,1,2 c. always contain ionic bonds d. conducts electricity when dissolved in water 25) How many significant figures are in the measurement g? a. 2 b. 3 c. 4 d ) How many significant figures are in the measurement 120,000 cm? a. 2 b. 3 c. 4 d. 5 28) A student used a balance and a graduated cylinder to collect the following data: Sample mass g Volume of water 20.0 ml Volume of water + metal sample 21.5 ml What is the calculated density of the metal? a g/cm 3 b g/cm 3 c. 6.8 g/cm 3 d. 2.1 g.cm 3 30) What is the reading on the graduated cylinder below? 23) Which of the following is a property of an ionic compound? a. relatively low melting point b. conducts electricity in the solid state c. relatively low boiling point d. conducts electricity when dissolved in water 24) Which of the following is true of molecular phosphate? compounds? a. 70 g/mol b. 116 g/mol a. relatively low melting point c. 164 g/mol d. 257 g/mol b. conducts electricity in the solid state a. 35 ml b. 36 ml c ml d ml 31) What is the mass of a solid whose density is 5.60 g/cm 3 and volume is 10.0 cm 3? a g b g c g d g 32) What is the gram formula mass of sodium

14 33) A compound consists of 72.2% magnesium and 27.8% nitrogen by mass. What is the empirical formula? a. MgN b. Mg 3 N 2 c. Mg 2 N 3 d. Mg 3 N 34) Which of the following is NOT an empirical formula? a. CO 2 b. C 6 H 12 O c. C 6 H 12 O 6 d. Al 3 O 2 35) What is the percentage of water in sodium tungstan dihydrate, Na 2 WO 4 2 H 2 O? a. 5.77% b % c. 36.0% d. 10.9% 36) Which of the following products is insoluble? a. K 2 SO 4 b. NaCl c. BaCl 2 d. Na 2 CO 3 37) What is the percentage, by mass, of sodium in Na 2 S 2 O 3? a. 29.1% b. 40.5% c. 30.4% d. 28.5%

Unit Five- Chemical Quantities Chapter 9: Mole ratios, conversions between chemicals in a balanced reaction (mole, mass), limiting reactant, % yield

Unit Five- Chemical Quantities Chapter 9: Mole ratios, conversions between chemicals in a balanced reaction (mole, mass), limiting reactant, % yield Chemistry Midterm Review Exam date: Wednesday, 2/15 during class The midterm exam must be completed before February vacation if you are absent The midterm exam is worth 6% of your year grade and it contains