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chemistry and chemical reactivity
Questions and Answers of
Chemistry And Chemical Reactivity
You are given 1.0-g samples of He, Fe, Li, Si, and C. Which sample contains the largest number of atoms? Which contains the smallest?
You are given 0.10-g samples of K, Mo, Cr, and Al. List the samples in order of the amount (moles), from smallest to largest.
Calculate the molar mass of each hydrated compound. The water of hydration is included in the molar mass.Given Data (a). Ni(NO3)2 ∙ 6 H2O(b). CuSO4 ∙ 5 H2O A CLOSER LOOK Hydrated lonic
Calculate the molar mass of each hydrated compound. Note that the water of hydration is included in the molar mass. Given Data (a). H2C2O4 ∙ 2 H2O (b). MgSO4 ∙ 7 H2O, Epsom salt A CLOSER
Analysis of a 10.0-g sample of apatite (a major component of tooth enamel) showed that it was made up of 3.99 g Ca, 1.85 g P, 4.14 g O, and 0.020 g H. List these elements based on relative amounts
A semiconducting material is composed of 52 g of Ga, 9.5 g of Al, and 112 g of As. Which element has the largest number of atoms in this material?
Calculate the molar mass of each of the following compounds: (a). Fe2O3, iron(III) oxide(b). BCl3, boron trichloride(c). C6H8O6, ascorbic acid (vitamin C)
Calculate the molar mass of each of the following compounds: (a). Fe(C6H11O7)2, iron(II) gluconate, a dietary supplement(b). CH3CH2CH2CH2SH, butanethiol, has a skunk like odor(c). C20H24N2O2,
Give the symbol, including the correct charge, for each of the following ions: (a). Permanganate ion (b). Nitrite ion (c). Dihydrogen phosphate ion (d). Ammonium ion (e). Phosphate ion (f).
Give the symbol, including the correct charge, for each of the following ions: (a). Barium ion (b). Titanium(IV) ion (c). Phosphate ion (d). Hydrogen carbonate ion (e). Sulfide ion (f).
What mass is represented by 0.0255 mol of each of the following compounds? (a). C3H7OH, 2-propanol, rubbing alcohol(b). C11H16O2, an antioxidant in foods, also known as BHA (butylated
Fill in the blanks in the table (one column per element). Symbol Number of protons Number of neutrons Number of electrons in the neutral atom Name of element 58 Ni 33g 10 10 30 25
Acetaminophen, whose structure is drawn below, is the active ingredient in some nonprescription pain killers. The recommended dose for an adult is two 500-mg caplets. How many molecules make up one
Calculate the mass percent of each element in the following compounds: (a). PbS, lead(II) sulfide, galena (b). C3H8, propane (c). C10H14O, carvone, found in caraway seed oil
An Alka-Seltzer tablet contains 324 mg of aspirin (C9H8O4), 1904 mg of NaHCO3, and 1000. mg of citric acid (H3C6H5O7). (The last two compounds react with each other to provide the “fizz,” bubbles
Calculate the mass percent of titanium in the mineral ilmenite, FeTiO3. What mass of ilmenite (in grams) is required if you wish to obtain 750 g of titanium?
Calculate the mass percent of each element in the following compounds:(a). C8H10N2O2, caffeine(b). C10H20O, menthol(c). CoCl2 ∙ 6 H2O
Calculate the mass percent of copper in CuS, copper(II) sulfide. If you wish to obtain 10.0 g of copper metal from copper(II) sulfide, what mass of CuS (in grams) must you use?
Acetylene is a colorless gas used as a fuel in welding torches, among other things. It is 92.26% C and 7.74% H. Its molar mass is 26.02 g/mol. What are the empirical and molecular formulas of
Succinic acid occurs in fungi and lichens. Its empirical formula is C2H3O2, and its molar mass is 118.1 g/mol. What is its molecular formula?
An organic compound has the empirical formula C2H4NO. If its molar mass is 116.1 g/mol, what is the molecular formula of the compound?
A large family of boron-hydrogen compounds has the general formula BxHy . One member of this family contains 88.5% B; the remainder is hydrogen. What is its empirical formula?
Cumene, a hydrocarbon, is a compound composed only of C and H. It is 89.94% carbon, and its molar mass is 120.2 g/mol. What are the empirical and molecular formulas of cumene?
In 2006, a Russian team discovered an interesting molecule they called “sulflower” because of its shape and because it was based on sulfur. It is composed of 57.17% S and 42.83% C and has a molar
Mandelic acid is an organic acid composed of carbon (63.15%), hydrogen (5.30%), and oxygen (31.55%). Its molar mass is 152.14 g/mol. Determine the empirical and molecular formulas of the acid.
Nicotine, a poisonous compound found in tobacco leaves, is 74.0% C, 8.65% H, and 17.35% N. Its molar mass is 162 g/mol. What are the empirical and molecular formulas of nicotine?
A compound containing xenon and fluorine was prepared by shining sunlight on a mixture of Xe (0.526 g) and excess F2 gas. If you isolate 0.678 g of the new compound, what is its empirical formula?
Elemental sulfur (1.256 g) is combined with fluorine, F2, to give a compound with the formula SFx , a very stable, colorless gas. If you have isolated 5.722 g of SFx , what is the value of x?
Epsom salt is used in tanning leather and in medicine. It is hydrated magnesium sulfate, MgSO4 ∙ 7 H2O. The water of hydration is lost on heating, with the number lost depending on the temperature.
The mass spectrum of nitrogen dioxide is illustrated here. (a) Identify the cations present for each of the four peaks in the mass spectrum.(b) Does the mass spectrum provide evidence that the two
The mass spectrum of phosphoryl chloride, POF3, is illustrated here.(a). Identify the cation fragment at a m/Z ratio of 85.(b). Identify the cation fragment at a m/Z ratio of 69.(c). Which two peaks
You combine 1.25 g of germanium, Ge, with excess chlorine, Cl2. The mass of product, GexCly, is 3.69 g. What is the formula of the product, GexCly?
The mass spectrum of CH3Cl is illustrated here. You know that carbon has two stable isotopes, 12C and 13C with relative abundances of 98.9% and 1.1%, respectively, and chlorine has two isotopes, 35Cl
The highest mass peaks in the mass spectrum of Br2 occur at m/Z 158, 160, and 162. The ratio of intensities of these peaks is approximately 1:2:1. Bromine has two stable isotopes, 79Br (50.7%
Crossword Puzzle: In the 2 × 2 box shown here, each answer must be correct four ways: horizontally, vertically, diagonally, and by itself. Instead of words, use symbols of elements. When the puzzle
The following chart shows a general decline in abundance with increasing mass among the first 30 elements. The decline continues beyond zinc. Notice that the scale on the vertical axis is
(a). What is the average mass of one copper atom? (b). Students in a college computer science class once sued the college because they were asked to calculate the cost of one atom and could not do
Reviewing the periodic table.(a) Name the element in Group 2A and the fifth period.(b) Name the element in the fifth period and Group 4B.(c) Which element is in the second period in Group 4A?(d)
Identify two nonmetallic elements that have allotropes and describe the allotropes of each.
Potassium has three naturally occurring isotopes (39K, 40K, and 41K), but 40K has a very low natural abundance. Which of the other two isotopes is more abundant? Briefly explain your answer.
In each case, decide which represents more mass:(a) 0.5 mol of Na, 0.5 mol of Si, or 0.25 mol of U(b) 9.0 g of Na, 0.50 mol of Na, or 1.2 × 1022 atoms of Na(c) 10 atoms of Fe or 10 atoms of K
The recommended daily allowance (RDA) of iron for women 19–30 years old is 18 mg. How many moles is this? How many atoms?
Which of the following is impossible?(a). Silver foil that is 1.2 × 10−4 m thick(b). A sample of potassium that contains 1.784 × 1024 atoms(c). A gold coin of mass 1.23 × 10−3 kg(d). 3.43 ×
Put the following elements in order from smallest to largest mass:(a) 3.79 × 1024 atoms Fe(b) 19.921 mol H2(c) 8.576 mol C(d) 7.4 mol Si(e) 9.221 mol Na(f) 4.07 × 1024 atoms Al(g) 9.2 mol Cl2
When a sample of phosphorus burns in air, the compound P4O10 forms. One experiment showed that 0.744 g of phosphorus formed 1.704 g of P4O10. Use this information to determine the ratio of the atomic
A reagent occasionally used in chemical synthesis is sodium–potassium alloy. (Alloys are mixtures of metals, and Na-K has the interesting property that it is a liquid.) One formulation of the alloy
Although carbon-12 is now used as the standard for atomic weights, this has not always been the case. Early attempts at classification used hydrogen as the standard, with the weight of hydrogen being
Which of the following samples has the largest number of ions?(a) 1.0 g of BeCl2(b) 1.0 g of MgCl2(c) 1.0 g of CaS(d) 1.0 g of SrCO3(e) 1.0 g of BaSO4
Write formulas for all of the compounds that can be made by combining the cations NH4+ and Ni2+ with the anions CO32− and SO42−.
The structure of one of the bases in DNA, adenine, is shown here. Which represents the greater mass: 40.0 g of adenine or 3.0 × 1023 molecules of the compound? Adenine
How many electrons are in a strontium atom (Sr)? Does an atom of Sr gain or lose electrons when forming an ion? How many electrons are gained or lost by the atom? When Sr forms an ion, the ion has
Write the molecular formula and calculate the molar mass for each of the molecules shown here. Which has the largest mass percent of carbon? Of oxygen?(a) Ethylene glycol (used in antifreeze)(b)
Capsaicin, the compound that gives the hot taste to chili peppers, has the formula C18H27NO3. (a) Calculate its molar mass. (b) If you eat 55 mg of capsaicin, what amount (moles) have you
Ionic and molecular compounds of the halogens. (a) What are the names of BaF2, SiCl4, and NiBr2?(b) Which of the compounds in part (a) are ionic, and which are molecular?(c) Which has the largest
A drop of water has a volume of about 0.050 mL. How many molecules of water are in a drop of water?
Calculate the molar mass and the mass percent of each element in the blue solid compound Cu(NH3)4SO4 ∙ H2O. What is the mass of copper and the mass of water in 10.5 g of the compound?
Ma huang, an extract from the ephedra species of plants, contains ephedrine. The Chinese have used this herb for more than 5000 years to treat asthma. More recently, ephedrine has been used in diet
Malic acid, an organic acid found in apples, contains C, H, and O in the following ratios: C1H1.50O1.25. What is the empirical formula of malic acid?
Your doctor has diagnosed you as being anemic— that is, as having too little iron in your blood. At the drugstore, you find two iron-containing dietary supplements: one with iron(II) sulfate,
Saccharin, a molecular model of which is shown below, is more than 300 times sweeter than sugar. It was first made in 1897, when it was common practice for chemists to record the taste of any new
A compound composed of iron and carbon monoxide, Fex(CO)y, is 30.70% iron. What is the empirical formula for the compound?
Name each of the following compounds and indicate which ones are best described as ionic:(a) ClF3(b) NCl3(c) SrSO4(d) Ca(NO3)2(e) XeF4(f) OF2(g) KI(h) Al2S3(i) PCl3(j) K3PO4
Complete the table by placing symbols, formulas, and names in the blanks. Cation Anion Name Ba²+ A1³+ CI- F- CO3²- ammonium bromide iron(II) chloride iron(III) oxide Formula BaS PbF₂
Write the formula for each of the following compounds and indicate which ones are best described as ionic:(a) Sodium hypochlorite(b) Boron triiodide(c) Aluminum perchlorate(d) Calcium acetate(e)
Empirical and molecular formulas.(a) Fluorocarbonyl hypofluorite is composed of 14.6% C, 39.0% O, and 46.3% F. The molar mass of the compound is 82 g/mol. Determine the empirical and molecular
Cacodyl, a compound containing arsenic, was reported in 1842 by the German chemist Robert Wilhelm Bunsen. It has an almost intolerable garlic-like odor. Its molar mass is 210 g/mol, and it is 22.88%
In the laboratory you combine 0.125 g of nickel with CO and isolate 0.364 g of Ni(CO)x . What is the value of x?
The action of bacteria on meat and fish produces a compound called cadaverine. As its name and origin imply, it stinks! (It is also present in bad breath and adds to the odor of urine.) It is 58.77%
Chromium is obtained by heating chromium(III) oxide with carbon. Calculate the mass percent of chromium in the oxide, and then use this value to calculate the quantity of Cr2O3 required to produce
A compound called MMT was once used to boost the octane rating of gasoline. What is the empirical formula of MMT if it is 49.5% C, 3.2% H, 22.0% O, and 25.2% Mn?
Elemental phosphorus is made by heating calcium phosphate with carbon and sand in an electric furnace. What is the mass percent of phosphorus in calcium phosphate? Use this value to calculate the
Stibnite, Sb2S3, is a dark gray mineral from which antimony metal is obtained. What is the mass percent of antimony in the sulfide? If you have 1.00 kg of an ore that contains 10.6% antimony, what
Iron pyrite, often called “fool’s gold,” has the formula FeS2. If you could convert 15.8 kg of iron pyrite to iron metal, what mass of the metal would you obtain?
Which of the following statements about 57.1 g of octane, C8H18, is (are) not true?(a) 57.1 g is 0.500 mol of octane.(b) The compound is 84.1% C by weight.(c) The empirical formula of the compound is
Direct reaction of iodine (I2) and chlorine (Cl2) produces an iodine chloride, IxCly , a bright yellow solid. If you completely consume 0.678 g of I2 in a reaction with excess Cl2 and produce 1.246 g
The formula of barium molybdate is BaMoO4. Which of the following is the formula of sodium molybdate?(a) Na4MoO(b) NaMoO(c) Na2MoO3(d) Na2MoO4(e) Na4MoO4
In a reaction, 2.04 g of vanadium combined with 1.93 g of sulfur to give a pure compound. What is the empirical formula of the product?
Pepto-Bismol, which can help provide relief for an upset stomach, contains 300. mg of bismuth subsalicylate, C21H15Bi3O12, per tablet. If you take two tablets for your stomach distress, what amount
The mass of 2.50 mol of a compound with the formula ECl4, in which E is a nonmetallic element, is 385 g. What is the molar mass of ECl4? What is the identity of E?
A metal M forms a compound with the formula MCl4. If the compound is 74.75% chlorine, what is the identity of M?
The weight percent of oxygen in an oxide that has the formula MO2 is 15.2%. What is the molar mass of this compound? What element or elements are possible for M?
A sample of hemoglobin is found to be 0.335% iron. What is the molar mass of hemoglobin if there are four iron atoms per molecule?
The elements A and Z combine to produce two different compounds: A2Z3 and AZ2. If 0.15 mol of A2Z3 has a mass of 15.9 g and 0.15 mol of AZ2 has a mass of 9.3 g, what are the atomic weights of A and Z?
In an experiment, you need 0.125 mol of sodium metal. Sodium can be cut easily with a knife (Figure 2.5), so if you cut out a block of sodium, what should the volume of the block be in cubic
Polystyrene can be prepared by heating styrene with tribromobenzoyl peroxide in the absence of air. A sample prepared by this method has the empirical formula Br3C6H3(C8H8)n, where the value of n can
Consider an atom of 64Zn. (a) Calculate the density of the nucleus in grams per cubic centimeter, knowing that the nuclear radius is 4.8 × 10−6 nm and the mass of the 64Zn atom is 1.06 × 10−22
Mass spectrometric analysis showed that there are four isotopes of an unknown element having the following masses and abundances: Three elements in the periodic table that have atomic weights near
A piece of nickel foil, 0.550 mm thick and 1.25 cm square, is allowed to react with fluorine, F2, to give a nickel fluoride. (a) How many moles of nickel foil were used? (The density of nickel is
Estimating the radius of a lead atom.(a) You are given a cube of lead that is 1.000 cm on each side. The density of lead is 11.35 g/ cm3. How many atoms of lead are in the sample? (b) Atoms are
Uranium is used as a fuel, primarily in the form of uranium(IV) oxide, in nuclear power plants. This question considers some uranium chemistry.(a) A small sample of uranium metal (0.169 g) is heated
If Epsom salt, MgSO4 ∙ x H2O, is heated to 250°C, all the water of hydration is lost. On heating a 1.687-g sample of the hydrate, 0.824 g of MgSO4 remains. How many molecules of water occur per
Tin metal (Sn) and purple iodine (I2) combine to form orange, solid tin iodide with an unknown formula. Weighed quantities of Sn and I2 are combined, where the quantity of Sn is more than is needed
The “alum” used in cooking is potassium aluminum sulfate hydrate, KAl(SO4)2 ∙ x H2O. To find the value of x, you can heat a sample of the compound to drive off all of the water and leave only
When analyzed, an unknown compound gave these experimental results: C, 54.0%; H, 6.00%; and O, 40.0%. Four different students used these values to calculate the empirical formulas shown here. Which
Consider the plot of relative element abundances on page 114. Is there a relationship between abundance and atomic number? Is there any difference between the relative abundance of an element of even
Two general chemistry students working together in the lab weigh out 0.832 g of CaCl2 ∙ 2 H2O into a crucible. After heating the sample for a short time and allowing the crucible to cool, the
The photo here depicts what happens when a coil of magnesium ribbon and a few calcium chips are placed in water.(a) Based on these observations, what might you expect to see when barium, another
To find the empirical formula of tin oxide, you first react tin metal with nitric acid in a porcelain crucible. The metal is converted to tin nitrate, but, on heating the nitrate strongly, brown
Identify, from the list below, the information needed to calculate the number of atoms in 1.00 cm3 of iron. Outline the procedure used in this calculation.(a) The structure of solid iron(b) The molar
A jar contains some number of jelly beans. To find out precisely how many are in the jar, you could dump them out and count them. How could you estimate their number without counting each one?
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