Problem 96
An organic compound was found to contain only C, H, and Cl. When a 1.50-g sample of the compound was completely combusted in air, 3.52 g of CO2 was formed. In a separate experiment, the chlorine in a 1.00-g sample of the compound was converted to 1.27 g of AgCl. Determine the empirical formula of the compound.
Problem 98a,b
An element X forms an iodide (XI3) and a chloride (XCl3). The iodide is quantitatively converted to the chloride when it is heated in a stream of chlorine: 2 XI3 + 3 Cl2 → 2 XCl3 + 3 I2 If 0.5000 g of XI3 is treated with chlorine, 0.2360 g of XCl3 is obtained. (a) Calculate the atomic weight of the element X. (b) Identify the element X.
Problem 99b
A method used by the U.S. Environmental Protection Agency (EPA) for determining the concentration of ozone in air is to pass the air sample through a 'bubbler' containing sodium iodide, which removes the ozone according to the following equation: O31g2 + 2 NaI1aq2 + H2O1l2¡ O21g2 + I21s2 + 2 NaOH1aq2 (b) How many grams of sodium iodide are needed to remove 1.3 mg of O3?
Problem 101
The fat stored in a camel's hump is a source of both energy and water. Calculate the mass of H2O produced by the metabolism of 1.0 kg of fat, assuming the fat consists entirely of tristearin 1C57H110O62, a typical animal fat, and assuming that during metabolism, tristearin reacts with O2 to form only CO2 and H2O.
- When hydrocarbons are burned in a limited amount of air, both CO and CO2 form. When 0.450 g of a particular hydrocarbon was burned in air, 0.467 g of CO, 0.733 g of CO2, and 0.450 g of H2O were formed. (a) What is the empirical formula of the compound? (b) How many grams of O2 were used in the reaction? (c) How many grams would have been required for complete combustion?
Problem 102
Problem 103
A mixture of N21g2 and H21g2 reacts in a closed container to form ammonia, NH31g2. The reaction ceases before either reactant has been totally consumed. At this stage 3.0 mol N2, 3.0 mol H2, and 3.0 mol NH3 are present. How many moles of N2 and H2 were present originally?
Problem 105c3
When a mixture of 10.0 g of acetylene (C2H2) and 10.0 g of oxygen (O2) is ignited, the resulting combustion reaction produces CO2 and H2O. (c) How many grams of CO2 and H2O are present after the reaction is complete?
Problem 105c1
When a mixture of 10.0 g of acetylene (C2H2) and 10.0 g of oxygen (O2) is ignited, the resulting combustion reaction produces CO2 and H2O. (c) How many grams of C2H2 are present after the reaction is complete?
- Boron nitride, BN, is an electrical insulator with remarkable thermal and chemical stability. Its density is 2.1 g/cm3. It can be made by reacting boric acid, H3BO3, with ammonia. The other product of the reaction is water. (b) If you made 225 g of boric acid react with 150 g of ammonia, what mass of BN could you make? (d) One application of BN is as a thin film for electrical insulation. If you take the mass of BN from part (b) and make a 0.4 mm thin film from it, what area, in cm2, would it cover?
Problem 106
Problem 109b
(b) Because atoms are spherical, they cannot occupy all of the space of the cube. The silver atoms pack in the solid in such a way that 74% of the volume of the solid is actually filled with the silver atoms. Calculate the volume of a single silver atom.
Problem 109c
Burning acetylene in oxygen can produce three different carbon-containing products: soot (very fine particles of graphite), CO(g), and CO2(g). (c) Why, when the oxygen supply is adequate, is CO2(g) the predominant carbon-containing product of the combustion of acetylene?
- Section 2.9 introduced the idea of structural isomerism, with 1-propanol and 2-propanol as examples. Determine which of these properties would distinguish these two substances: (a) boiling point, (b) combustion analysis results, (c) molecular weight, (d) density at a given temperature and pressure. You can check on the properties of these two compounds in Wolfram Alpha (http://www.wolframalpha.com/) or the CRC Handbook of Chemistry and Physics.
Problem 111
- A 3.50 g of an alloy which contains only lead and tin is dissolved in hot HNO3. Excess sulfuric acid is added to this solution and 1.57g of PbSO4(s) is obtained. (b) Assuming all the lead in the alloy reacted to form PbSO4, what was the amount, in grams, of lead and tin in the alloy respectively?
Problem 112
Problem 113a,b
Hydrogen cyanide, HCN, is a poisonous gas. The lethal dose is approximately 300 mg HCN per kilogram of air when inhaled. (a) Calculate the amount of HCN that gives the lethal dose in a small laboratory room measuring 3.5 × 4.5 × 2.5 m. The density of air at 26 °C is 0.00118 g/cm3. (b) If the HCN is formed by reaction of NaCN with an acid such as H2SO4, what mass of NaCN gives the lethal dose in the room? 2 NaCN(s) + H2SO4(aq) → Na2SO4(aq) + 2 HCN(g)
Problem 113c
Hydrogen cyanide, HCN, is a poisonous gas. The lethal dose is approximately 300 mg HCN per kilogram of air when inhaled. (c) HCN forms when synthetic fibers containing Orlon® or Acrilan ® burn. Acrilan® has an empirical formula of CH2CHCN, so HCN is 50.9% of the formula by mass. A rug measures 3.5 × 4.5 m and contains 850 g of Acrilan® fibers per square yard of carpet. If the rug burns, will a lethal dose of HCN be generated in the room? Assume that the yield of HCN from the fibers is 20% and that the carpet is 50% consumed.
Problem 114a
The source of oxygen that drives the internal combustion engine in an automobile is air. Air is a mixture of gases, principally N2(79%) and O2(20%). In the cylinder of an automobile engine, nitrogen can react with oxygen to produce nitric oxide gas, NO. As NO is emitted from the tailpipe of the car, it can react with more oxygen to produce nitrogen dioxide gas. (a) Write balanced chemical equations for both reactions.
Problem 114b
The source of oxygen that drives the internal combustion engine in an automobile is air. Air is a mixture of gases, principally N2(79%) and O2(20%). In the cylinder of an automobile engine, nitrogen can react with oxygen to produce nitric oxide gas, NO. As NO is emitted from the tailpipe of the car, it can react with more oxygen to produce nitrogen dioxide gas. (b) Both nitric oxide and nitrogen dioxide are pollutants that can lead to acid rain and global warming; collectively, they are called 'NOx' gases. In 2009, the United States emitted an estimated 19 million tons of nitrogen dioxide into the atmosphere. How many grams of nitrogen dioxide is this?
Problem 114c
The source of oxygen that drives the internal combustion engine in an automobile is air. Air is a mixture of gases, principally N2(79%) and O2(20%). In the cylinder of an automobile engine, nitrogen can react with oxygen to produce nitric oxide gas, NO. As NO is emitted from the tailpipe of the car, it can react with more oxygen to produce nitrogen dioxide gas. (c) The production of NOx gases is an unwanted side reaction of the main engine combustion process that turns octane, C8H18, into CO2 and water. If 85% of the oxygen in an engine is used to combust octane and the remainder used to produce nitrogen dioxide, calculate how many grams of nitrogen dioxide would be produced during the combustion of 500 g of octane.
Problem 115b
The thermite reaction, Fe2O3 + Al → Al2O3 + Fe produces so much heat that the Fe product melts. This reaction is used industrially to weld metal parts under water, where a torch cannot be employed. It is also a favorite chemical demonstration in the lecture hall (on a small scale). (b) Calculate how many grams of aluminum are needed to completely react with 500.0 g of Fe2O3 in this reaction.
Problem 115c
The thermite reaction, Fe2O3 + Al → Al2O3 + Fe produces so much heat that the Fe product melts. This reaction is used industrially to weld metal parts under water, where a torch cannot be employed. It is also a favorite chemical demonstration in the lecture hall (on a small scale). (c) This reaction produces 852 kJ of heat per mole of Fe2O3 reacted. How many grams of Fe2O3 are needed to produce 1.00 × 104 kJ of heat?
Problem 115d
The thermite reaction, Fe2O3 + Al S Al2O3 + Fe produces so much heat that the Fe product melts. This reaction is used industrially to weld metal parts under water, where a torch cannot be employed. It is also a favorite chemical demonstration in the lecture hall (on a small scale). (d) If you performed the reverse reaction— aluminum oxide plus iron makes iron oxide plus aluminum—would that reaction have heat as a reactant or a product?
- One of the most bizarre reactions in chemistry is called the Ugi reaction: R1C(=O)R2 + R3 - NH2 + R4COOH + R5NC S R4C(=O)N(R3)C(R1R2)C=ONHR5 + H2O
Problem 116
(a) Write out the balanced chemical equation for the Ugi reaction, for the case where R = CH3CH2CH2CH2CH2CH2— (this is called the hexyl group) for all compounds.
Ch.3 - Chemical Reactions and Reaction Stoichiometry
