Chemistry CA 2 Practice

Transcription

1 hemistry 2 Practice

2 Some questions (c) 2015 by Region 10 Educational Service enter. Some questions (c) 2015 by Progress Testing. Page 2

3 1 Which of the following is the mass in grams of ³ mol of N2? g g g g 2 Zachary is tasked with carefully measuring precisely one mole of aluminum. How should Zachary go about completing this assignment? He should obtain 27 aluminum pellets. He should obtain 27 grams of aluminum. He should obtain 13 grams of aluminum. 5 student mixes 36.0 grams of silver nitrate solution with 30.0 grams of sodium chromate solution. The mass of the products, which includes the resulting solution and precipitate, is equal to 66.0 grams. Which of the following best explains these results? law of conservation of mass law of definite proportions law of multiple proportions law of conservation of energy 6 Which of the following is the scientific name for Lil? chlorine lithide chlorolithium He should obtain 27 atoms of aluminum. lithium chloride lithium chlorine 3 mixture of iron and sulfur can be separated by attracting the iron particles with a magnet. If the iron and sulfur mixture is heated strongly, iron (II) sulfide forms, which is no longer magnetic and cannot be separated by physical methods. What is iron (II) sulfide? element compound homogenous mixture heterogeneous mixture 4 Which particles are represented by the dots in Lewis dot diagram? core electrons 7 What is the empirical formula for the compound that has 46 grams of sodium, 64 grams of sulfur, and 48 grams of oxygen? Na2S2O3 Na3S2O2 Na2S2O2 Na3S3O3 8 Which of the following is a balanced chemical equation describing the formation of water? H2 + O2 H2O H2 + 2O2 H2O valence electrons 2H2 + O2 2H2O protons 2H2 + 2O2 2H2O all electrons Page 3

4 9 Which of the following is the correct Lewis dot diagram? 12 How many molecules are in 2.50 moles of H2O? 1.51 X molecules of H2O 4.15 X molecules of H2O 3.01 X molecules of H2O 8.31 X molecules of H2O 10 What is the empirical formula of a compound that has 40% carbon, 6.7% hydrogen, and 53.3% oxygen? H2O 2HO 2H2O2 13 Vinegar, a common household item, is used in cleaning, cooking, baking and meat preservation. Vinegar contains acetic acid, H3OOH, which gives vinegar its sour taste and pungent smell. What is the percent composition of carbon in acetic acid? 40.0% 41.4% 20.0% 33.3% HO2 11 What is the molecular formula of a compound that has a molecular weight of grams? gram sample contains 2.00 grams of carbon, 0.34 grams of hydrogen, and 2.69 grams of oxygen. 6H12O6 8H16O8 16H32O16 14 compound is found to have an empirical formula of H2O. What is the molecular formula when the molecular weight is grams? 2H4O2 6H8O6 6H12O6 12H24O12 5H10O5 Page 4

5 15 Which of the following is a single replacement reaction? ao3(s) ao(s) + O2(g) 4l(s) + 3O2(g) 2l2O3(s) Mg(s) + 2Hl(aq) H2(g) +Mgl2(aq) 24H10(g) + 13O2(g) 8O2(g) + 10H2O(g) 16 The unbalanced equation below represents the reaction of solid aluminum hydroxide with hydrochloric acid. l(oh)3 + Hl --> ll3 + H2O Which of the following represents the correct, balanced chemical equation for the above reaction? l(oh)3 + Hl3 --> ll3 + 2 H2O l(oh)3 + Hl3 --> ll3 + 4 H2O l(oh)3 + 3 Hl --> ll3 + 3 H2O l(oh)3 + 3 Hl --> ll3 + 6 H2O 17 uring the combustion of methane (H4), one mole of methane gas combines with two moles of oxygen gas (O2) to produce one mole of carbon dioxide gas (O2) and two moles of water vapor. Which of the following chemical equations correctly represents the combustion of methane described above? H4(g) + 2O(g) O(g) + 2H2O(l) H4(g) + 2O2(g) O(g) + 2H2O(l) H4(g) + 2O2(g) O2(g) + 2H2O(g) H4(g) + 2O(g) O2(g) + 2H2O(g) 18 What is the molar mass of Kr? 19 How many moles are there in 8.50 X g/mol molecules of sodium sulfate? 74.1 g/mol 1.40 moles 119 g/mol 14.1 moles 1.20 X g/mol 51.2 moles 5.12 X moles Page 5

6 20 Which of the following has the highest mass? 50.0 g water 24 The following picture shows a covalent molecule mol Nal 50.0 molecules carbon dioxide 50.0 mg of oxygen gas 21 What mass of sulfur would have precisely 4.7 x atoms of sulfur? 6.02 g sulfur 4.7 g sulfur What molecule listed below has the same shape? 2.5 g sulfur H3 1.3 g sulfur H2O2 22 What is the molar mass of O2? 22.0 g/mol NH3 Na3P 28.0 g/mol 44.0 g/mol 56.0 g/mol 25 What is the molar mass of carbon? 6.0 g/mol 12.0 g/mol 23 Which of the following molecules has a central atom with precisely two unshared pairs of electrons? 22.4 g/mol 6.02 X g/mol ammonia, NH3 methane, H4 water, H2O hydrocyanic acid, HN 26 Which of the following compounds would NOT be expected to exhibit a linear molecular geometry? carbon dioxide, O2 beryllium fluoride, ef2 hydrogen sulfide, H2S hydrocyanic acid, HN Page 6

7 27 student carefully measures a certain quantity of four different substances into trays that will be used in a laboratory exercise. Which of these trays would contain the largest number of atoms? sample mass of empty tray mass of tray with sample water g g table salt (Nal) g g copper wire g g lead shot g g water table salt copper wire lead shot 28 What is a mole in chemistry terms? a mammal found in Eurasia and North merica an SI unit for measuring the amount of a substance a benign tumor sometimes found on human skin appearing as a small, sometimes raised area of skin, usually with darker pigment a Mexican sauce made from chili peppers, other spices, and chocolate 29 What is the molecular shape of a l4 molecule? 31 Which of the following molecules would be expected to exhibit a tetrahedral geometry? bent linear tetrahedral trigonal planar NH3 H2O H2O H4 30 round the central atom in a covalently bonded molecule, there are four pairs of electrons: three shared pairs and one unshared pair. The geometry of this molecule is best described as linear 32 Which of the following molecules would be expected to exhibit a trigonal planar geometry? NH3 H2O trigonal planar H2O trigonal pyramidal H4 tetrahedral Page 7

8 33 What is the shape of a O2 molecule? linear tetrahedral trigonal planar 38 Which of the following is the metallic ion in sodium fluoride? Na 1- Na 1+ bent F 2-34 Which of the following is the correct formula for mercury(ii) chloride? Hgl Hgl2 Hg2l F Which of the following best describes the arrangement of electrons in a metallic bond? Electrons are transferred from one atom to another. Hg2l2 Electrons exist as shared electron pairs between neutral atoms. 35 What is the formula for copper (I) oxide? u2o3 Electrons are delocalized in a "sea of electrons" and are shared among the positively charged metal ions. u2o uo2 uo Electrons are shared unequally, creating a bond with partial positive and negative poles. 36 What is the formula for sodium fluoride? NaF Na2F 40 What is the formula mass of potassium chloride, Kl? NaF amu Na2F amu amu 37 What is the formula for iron (II) oxide? amu Fe2O2 Fe2O FeO FeO2 Page 8

9 41 How many hydrogen atoms are there in 7.30 moles of ethanol (2H5OH)? 1.21 X atoms 2.20 X atoms 2.64 X atoms 4.39 X atoms 44 The percent by mass of oxygen in Na2SO4 (gram formula mass = 142 grams) is closest to which of the following? 64% 45% 11% 22% 42 What is the mass percent of carbon in glucose, 6H12O6? 45 What is the percent by mass of sulfur in sulfur dioxide? 25.00% 40.00% 41.40% 72.07% 32% 33% 67% 50% 43 What is the approximate percent by mass of aluminum in l2o3? 18.9% 47.1% 52.9% 35.4% 46 What is the approximate percent composition by mass of ar2 (gram formula mass = 200 grams)? 35% calcium and 65% bromine 25% calcium and 75% bromine 30% calcium and 70% bromine 20% calcium and 80% bromine Page 9

10 47 What is the percent by mass of oxygen in Fe2O3 (gram formula mass = 160 grams)? 51 The percent by mass of oxygen in H22O4 is equal to which of the following expressions? 56% 30% 70% 16% 48 What is the approximate percent by mass of oxygen in SO3? 60% 40% 20% 80% 49 What is the approximate percent by mass of potassium in KHO3? 39% 24% 19% 61% 52 One step in the production of copper is to heat copper (I) sulfide, u2s, with oxygen. This produces copper (I) oxide and sulfur dioxide gas according to the following reaction: 2 u2s(s) + 3 O2(g) -> 2 u2o(s) + 2 SO2(g) Which is the greatest mass of SO2 that can be produced from 15.0 mol u2s? 50 What is the percent by mass of hydrogen in NH3 (gram formula mass = 17.0 grams)? 17.6% 82.4% 21.4% 5.9% ² g SO ² g SO ² g SO ³ g SO2 Page 10

11 53 The percent by mass of nitrogen in Mg(N)2 is equal to which of the following? 55 queous lead nitrate is combined with aqueous potassium chromate to form solid lead chromate and potassium nitrate in solution. If 25.0 grams of each reactant is used, what is the percent yield of lead chromate if 20.0 grams of PbrO4 is collected? K2rO4 + Pb(NO3)2 à PbrO4 + 2KNO % 66.6 % 69.0 % 81.5 % 56 The reaction between solid sodium and iron (III) oxide is one of a series of reactions that inflate an automobile airbag. 6 Na(s) + Fe2O3(s) à 3 Na2O (s) + 2 Fe (s) 54 student burns 1.50 mol 3H8 according to the following reaction: 3H8 + 5O2 3O2 + 4H2O. How many grams of carbon dioxide are produced? ¹ g ¹ g If 25.0 grams of each reactant is used, what is the limiting reactant? Na Fe2O3 Na2O Fe ² g ² g Page 11 E SURE YOU HVE REORE LL OF YOUR NSWERS ON YOUR NSWER OUMENT STOP