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general chemistry principles
Questions and Answers of
General Chemistry Principles
Potassium-40 is one of the few naturally occurring radioactive isotopes of elements of low atomic number. Its percent isotopic abundance among K isotopes is 0.012%. How many 40K atoms are present in
When 3.06 g hydrogen was allowed to react with an excess of oxygen, 27.35 g water was obtained. In a second experiment, a sample of water was decomposed by electrolysis, resulting in 1.45 g hydrogen
In one experiment, the burning of 0.312 g sulfur produced 0.623 g sulfur dioxide as the sole product of the reaction. In a second experiment, 0.842 g sulfur dioxide was obtained. What mass of sulfur
In one experiment, the reaction of 1.00 g mercury and an excess of sulfur yielded 1.16 g of a sulfide of mercury as the sole product. In a second experiment, the same sulfide was produced in the
Sulfur forms two compounds with oxygen. In the first compound, 1.000 g sulfur is combined with 0.998 g oxygen, and in the second, 1.000 g sulfur is combined with 1.497 g oxygen. Show that these
The following observations were made for a series of five oil drops in an experiment similar to Millikan’s (see Figure 2-8). Drop 1 carried a charge of 1.28 x 10-18 C; drops 2 and 3 each
Use data from Table 2.1 to verify that(a) The mass of electrons is about 1/2000 that of H atoms;(b) The mass-to-charge ratio (m/e) for positive ions is considerably larger than that for
Determine the approximate value of m/e in grams per coulomb for the ions 12753I- and 3216S2- Why are these values only approximate?
The following radioactive isotopes have applications in medicine. Write their symbols in the form AZE.(a) Cobalt-60; (b) Phosphorus-32; (c) Iron-59; (d) Radium-226.
For the isotope 202Hg, express the percentage of the fundamental particles in the nucleus that are neutrons.
Through an appropriate symbol, indicate the number of protons, neutrons, and electrons in (a) An atom of barium-135 and(b) The double negatively charged ion of selenium-80.
A compound contains only Fe and O. A 0.2729 g sample of the compound was dissolved in 50 mL of concentrated acid solution, reducing all the iron to Fe2+ ions. The resulting solution was diluted to
Warfarin, C19H16O4, is the active ingredient used in some anticoagulant medications. The amount of warfarin in a particular sample was determined as follows. A 13.96 g sample was first treated with
Copper refining traditionally involves “roasting” insoluble sulfide ores (CuS) with oxygen. Unfortunately, the process produces large quantities of SO2(g), which is a major contributor to
Phosphorus is essential for plant growth, but an excess of phosphorus can be catastrophic in aqueous ecosystems. Too much phosphorus can cause algae to grow at an explosive rate and this robs the
Manganese is derived from pyrolusite ore, an impure manganese dioxide. In the procedure used to analyze a pyrolusite ore for its MnO2 content, a 0.533 g sample is treated with 1.651 g oxalic acid
Sodium cyclopentadienide, NaC5H5, is a common reducing agent in the chemical laboratory, but there is a problem in using it: NaC5H5 is contaminated with tetrahydrofuran (THF), C4H8O, a solvent used
In this problem, we describe an alternative method for balancing equations for oxidation-reduction reactions. The method is similar to the method given previously in Tables 5.5 and 5.6, but it places
The Kjeldahl method is used in agricultural chemistry to determine the percent protein in natural products. The method is based on converting all the protein nitrogen to ammonia and then determining
In your own words, define or explain the terms or symbols (a) ⇌ (b) [ ]; (c) Spectator ion; (d) Weak acid.
Briefly describe (a) Half-equation method of balancing redox equations; (b) Disproportionation reaction;(c) Titration; (d) Standardization of a solution.
Explain the important distinctions between (a) A strong electrolyte and strong acid; (b) An oxidizing agent and reducing agent; (c) Precipitation reactions and neutralization reactions; (d)
The number of moles of hydroxide ion in 0.300 L of 0.0050 M Ba(OH)2 is (a) 0.0015; (b) 0.0030; (c) 0.0050;(d) 0.010.
The highest [H+] will be found in an aqueous solution that is (a) 0.10 M HCl; (b) 0.10 M NH3; (c) 0.15 M CH3COOH;(d) 0.10 M H2SO4.
To precipitate Zn2+ from Zn(NO3)2(aq), add(a) NH4Cl; (b) MgBr2; (c) K2CO3; (d) (NH4)2SO4.
When treated with dilute HCl(aq), the solid that reacts to produce a gas is (a) BaSO3; (b) ZnO;(c) NaBr; (d) Na2SO4.
An unknown solid compound dissolves readily when added to water, forming a solution that conducts electricity. A precipitate forms when Ba(NO3)2(aq) is added to a solution of this compound, but not
In the equationthe missing coefficients (a) Are each 2; (b) Are each 4;(c) Can have any values as long as they are the same;(d) Must be determined by experiment. ? Fe²+ (aq) + O₂(g) O₂(g) +
What is the net ionic equation for the reaction that occurs when an aqueous solution of KI is added to an aqueous solution of Pb(NO3)2?
When aqueous sodium carbonate, Na2CO3, is treated with dilute hydrochloric acid, HCl, the products are sodium chloride, water, and carbon dioxide gas. What is the net ionic equation for this reaction?
Balance the following oxidation–reduction equations.(a) Cl2(aq) → Cl-(aq) + ClO-(aq) (basic solution)(b) C2O42-(aq) + MnO4-(aq) → Mn2+(aq) + CO2(g) (acidic solution)
Describe the synthesis of each of the following ionic compounds, starting from solutions of sodium and nitrate salts. Then write the net ionic equation for each synthesis.(a) Zn3(PO4)2;(b)
What is the simplest ratio a:b when the equation below is properly balanced?(a) 2:5; (b) 5:2; (c) 1:5; (d) 5:1; (e) 2:3. acidic a CIO (aq) + bl₂(aq) solution cCl(aq) + d IO3(aq)
In the half-reaction in which NpO2+ is converted to Np4+, the number of electrons appearing in the half-equation is (a) 1; (b) 2; (c) 3; (d) 4.
Which list of compounds contains a nonelectrolyte, a weak electrolyte, and a strong electrolyte? (a) CO2, NaCl, MnSO4; (b) H2SO4, CH3COOH, CuCl; (c) SO2, HF, FeSO4; (d) Ba(ClO3)2, K2S2O3,
Which list of compounds contains a weak acid, a weak base, and a salt? (a) HCl, NH3, Na2SO4;(b) HNO2, NH3, NH4NO2; (c) HCl, Ca(OH)2, CaSO4;(d) HNO2, KOH, Cs2CrO4; (e) None of these.
Which list of compounds contains two soluble compounds and an insoluble one?(a) HgBr2, MnSO4, Na2C2O4;(b) Na2S2O3, NH4Cl, CoI2;(c) MnS, Cu(OH)2, Al2O3;(d) Pb(ClO4)2, Ca(NO3)2, Hg2SO4;(e) None of
Classify each of the following statements as true or false.(a) Barium chloride, BaCl2, is a weak electrolyte in aqueous solution.(b) In the reaction H-(aq) + H2O(l): H2(g) + OH-(aq), water acts as
Which of the following reactions are oxidation–reduction reactions?(a) H2CO3(aq) → H2O(l) + CO2(g)(b) 2 Li(s) + 2 H2O(l) → 2 LiOH(aq) + H2(g)(c) 4 Ag(s) + PtCl4(aq) → 4 AgCl(s) + Pt(s)(d) 2
Similar to Figure 5-4(c), but using the formulas HAc, Ac- and H3O+, give a more accurate representation of CH3COOH(aq) in which ionization is 5% complete.Figure 5-4(c) + (c)
For the ion 228Ra2+ with a mass of 228.030 u, determine(a) The numbers of protons, neutrons, and electrons in the ion;(b) The ratio of the mass of this ion to that of an atom of 16O.
An isotope of silver has a mass that is 6.68374 times that of oxygen-16. What is the mass in u of this isotope?
The ratio of the masses of the two naturally occurring isotopes of indium is 1.0177:1. The heavier of the two isotopes has 7.1838 times the mass of 16O. What are the masses in u of the two isotopes?
The four naturally occurring isotopes of strontium have the atomic masses 83.9134 u; 85.9093 u; 86.9089 u; and 87.9056 u. The percent isotopic abundance of the lightest isotope is 0.56% and of the
The following ratios of masses were obtained with a mass spectrometer: 199F/126C = 1.5832; 3517Cl/199F = 1.8406; 8135Br/3517Cl = 2.3140; Determine the mass of a 8135Br atom in amu.
Which of the following species has(a) Equal numbers of neutrons and electrons;(b) Protons, neutrons, and electrons in the ratio 9:11:8;(c) A number of neutrons equal to the number of protons plus
Given the same species as listed in Exercise 33, which has(a) Equal numbers of neutrons and protons;(b) Protons contributing more than 50% of the mass;(c) About 50% more neutrons than
An isotope with mass number 44 has four more neutrons than protons. This is an isotope of what element?
Identify the isotope X that has one more neutron than protons and a mass number equal to nine times the charge on the ion X3+.
Iodine has many radioactive isotopes. Iodine-123 is a radioactive isotope used for obtaining images of the thyroid gland. Iodine-123 is administered to patients in the form of sodium iodide capsules
Iodine-131 is a radioactive isotope that has important medical uses. Small doses of iodine-131 are used for treating hyperthyroidism (overactive thyroid) and larger doses are used for treating
Americium-241 is a radioactive isotope that is used in high-precision gas and smoke detectors. How many neutrons, protons, and electrons are there in an atom of americium-241?
Some foods are made safer to eat by being exposed to gamma rays from radioactive isotopes, such as cobalt-60. The energy from the gamma rays kills bacteria in the food. How many neutrons, protons,
Which statement is probably true concerning the masses of individual chlorine atoms: All have, some have, or none has a mass of 35.45 u? Explain.
The mass of a carbon-12 atom is taken to be exactly 12 u. Are there likely to be any other atoms with an exact integral (whole number) mass, expressed in u? Explain.
Magnesium has three naturally occurring isotopes. Their masses are 23.985042 u, 24.985837 u, and 25.982593 u. What is the weighted-average atomic mass of magnesium in a sample for which the percent
There are four naturally occurring isotopes of chromium. Their masses and percent isotopic abundances are 49.9461 u, 4.35%; 51.9405 u, 83.79%; 52.9407 u, 9.50%; and 53.9389 u, 2.36%. Calculate the
The two naturally occurring isotopes of silver have the following abundances: 107Ag, 51.84%; 109Ag, 48.16%. The mass of 107Ag is 106.905092 u. What is the mass of 109Ag?
Gallium has two naturally occurring isotopes. One of them, gallium-69, has a mass of 68.925581 u and a percent isotopic abundance of 60.11%. What must be the mass and percent isotopic abundance of
The three naturally occurring isotopes of potassium are 39K, 38.963707 u; 40K, 39.963999 u; and 41K. The percent isotopic abundances of 39K and 41K are 93.2581% and 6.7302%, respectively. Determine
A mass spectrum of germanium displayed peaks at mass numbers 70, 72, 73, 74, and 76, with relative heights of 20.5, 27.4, 7.8, 36.5, and 7.8, respectively.(a) In the manner of Figure 2-14, sketch
Use the conventional atomic mass of boron to estimate the fractional isotopic abundances of the two naturally occurring isotopes, 10B and 11B These isotopes have masses of 10.012937 u and
Hydrogen and chlorine atoms react to form simple diatomic molecules in a 1:1 ratio, that is, HCl. The percent isotopic abundances of the chlorine isotopes are 35Cl and 37Cl are estimated to be 75.77%
Refer to the periodic table inside the front cover and identify(a) The element that is in group 14 and the fourth period(b) One element similar to and one unlike sulfur(c) The alkali metal in the
Refer to the periodic table inside the front cover and identify(a) The element that is in group 11 and the sixth period(b) An element with atomic number greater than 50 that has properties similar to
Assuming that the seventh period of the periodic table has 32 members, what should be the atomic number of (a) The noble gas following radon (Rn);(b) The alkali metal following francium (Fr)?
Find the several pairs of elements that are “out of order” in terms of increasing atomic mass and explain why the reverse order is necessary.
What is the total number of atoms in (a) 15.8 mol Fe;(b) 0.000467 mol Ag; (c) 8.5 x 10-11 mol Na?
Without doing detailed calculations, indicate which of the following quantities contains the greatest number of atoms: 6.022 x 1023 Ni atoms, 25.0 g nitrogen, 52.0 g Cr, 10.0 cm3 Fe (d = 7.86 g/cm3).
Determine(a) The number of moles of Zn in a 415.0 g sample of zinc metal(b) The number of Cr atoms in 147.4 kg chromium(c) The mass of a one-trillion-atom (1.0 x 1012) sample of metallic gold(d) The
Determine(a) The number of Kr atoms in a 5.25 mg sample of krypton(b) The molar mass, M, and identity of an element if the mass of a 2.80 x 1022 atom sample of the element is 2.09 g(c) The mass of a
How many Cu atoms are present in a piece of sterling silver jewelry weighing 33.24 g? (Sterling silver is a silver–copper alloy containing 92.5% Ag by mass.)
How many atoms are present in a sample of plumber’s solder, a lead–tin alloy containing 67% Pb by mass and having a density of 9.4 g/cm3?
How many 204Pb atoms are present in a piece of lead weighing 215 mg? The percent isotopic abundance of 204Pb is 1.4%.
A particular lead–cadmium alloy is 8.0% cadmium by mass. What mass of this alloy, in grams, must you weigh out to obtain a sample containing 7.25 x 1023 Cd atoms?
Medical experts generally believe a level of 30 μg Pb per deciliter of blood poses a significant health risk (1 dL = 0.1 L). Express this level (a) In the unit mol Pb/L blood;(b) As the number of
During a severe episode of air pollution, the concentration of lead in the air was observed to be 3.11 μg Pb/m3. How many Pb atoms would be present in a 0.500 L sample of this air (the volume of air
Without doing detailed calculations, determine which of the following samples has the greatest number of atoms:(a) A cube of iron with a length of 10.0 cm (d = 7.86 g/cm3)(b) 1.00 kg of hydrogen
A solution was prepared by dissolving 2.50 g potassium chlorate (a substance used in fireworks and flares) in 100.0 mL of water at 40 °C. When the solution was cooled to 20 °C, its volume was still
William Prout (1815) proposed that all other atoms are built up of hydrogen atoms, suggesting that all elements should have integral atomic masses based on an atomic mass of one for hydrogen. This
Use 1 x 10-13 cm as the approximate diameter of the spherical nucleus of the hydrogen-1 atom, together with data from Table 2.1, to estimate the density of matter in a proton.Table 2.1 TABLE 2.1
Fluorine has a single atomic species,19F. Determine the atomic mass of 19F. by summing the masses of its protons, neutrons, and electrons, and compare your results with the value listed on the
Use fundamental definitions and statements from Chapters 1 and 2 to establish the fact that 6.022 x 1023 u = 1.000 g.
In each case, identify the element in question.(a) The mass number of an atom is 234, and the atom has 60.0% more neutrons than protons.(b) An ion with a +2 charge has 10.0% more protons than
Determine the only possible +2 ion for which the following two conditions are both satisfied:• The net ionic charge is one-tenth the nuclear charge.• The number of neutrons is four more than the
Determine the only possible isotope (E) for which the following conditions are met:• The mass number of E is 2.50 times its atomic number.• The atomic number of E is equal to the mass number of
The masses of the naturally occurring mercury isotopes are 196Hg, 195.9658 u; 198Hg, 197.9668 u; 199Hg, 198.9683 u; 200Hg, 199.9683 u; 201Hg, 200.9703 u; 202Hg, 201.9706 u; and 204Hg, 203.9735
Suppose we redefined the atomic mass scale by arbitrarily assigning to the naturally occurring mixture of chlorine isotopes an atomic mass of 35.00000 u.(a) What would be the atomic masses of helium,
The two naturally occurring isotopes of nitrogen have masses of 14.0031 and 15.0001 u, respectively. Use the conventional atomic mass of nitrogen to estimate the percentage of 15N atoms in naturally
Germanium has three major naturally occurring isotopes: 70Ge (69.92425 u, 20.85%), 72Ge (71.92208 u, 27.54%), 74Ge (73.92118 u, 36.29%). There are also two minor isotopes: 73Ge (72.92346 u) and
The two naturally occurring isotopes of chlorine are 35Cl (34.9689 u, 75.77%) and 37Cl (36.9658 u, 24.23%). The two naturally occurring isotopes of bromine are 79Br (78.9183 u, 50.69%) and 81Br
From the densities of the lines in the mass spectrum of krypton gas, the following observations were made:• Somewhat more than 50% of the atoms were krypton-84.• The numbers of krypton-82 and
How many atoms are present in a 1.50 m length of 20-gauge copper wire? A 20-gauge wire has a diameter of 0.03196 in., and the density of copper is 8.92 g/cm3.
Monel metal is a corrosion-resistant copper–nickel alloy used in the electronics industry. A particular alloy with a density of 8.80 g/cm3 and containing 0.022% Si by mass is used to make a
Deuterium, 2H (2.0140 u), is sometimes used to replace the principal hydrogen isotope in chemical studies. The percent isotopic 1H abundance of deuterium is 0.015%. If it can be done with 100%
An alloy that melts at about the boiling point of water has Bi, Pb, and Sn atoms in the ratio 10:6:5, respectively. What mass of alloy contains a total of one mole of atoms?
A particular silver solder (used in the electronics industry to join electrical components) is to have the atom ratio of 5.00 Ag/4.00 Cu/1.00 Zn. What masses of the three metals must be melted
A low-melting Sn–Pb–Cd alloy called eutectic alloy is analyzed. The mole ratio of tin to lead is 2.73:1.00, and the mass ratio of lead to cadmium is 1.78:1.00. What is the mass percent
In an experiment, 125 cm3 of zinc and 125 cm3 of iodine are mixed together and the iodine is completely converted to 164 cm3 of zinc iodide. What volume of zinc remains unreacted? The densities of
The data Lavoisier obtained in the experiment described on page 35 are as follows:How closely did Lavoisier’s results conform to the law of conservation of mass? (1 livre = 16 onces; 1 once = 8
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