Chemistry: The Molecular Science
Chemistry: The Molecular Science
5th Edition
ISBN: 9781285199047
Author: John W. Moore, Conrad L. Stanitski
Publisher: Cengage Learning
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Chapter 2, Problem 131QRT

Uranium is used as a fuel, primarily in the form of uranium(IV) oxide, in nuclear power plants. This question considers some uranium chemistry.

  1. (a) A small sample of uranium metal (0.169 g) is heated to 900 °C in air to give 0.199 g of a dark green oxide, UxOy. How many moles of uranium metal were used? What is the empirical formula of the oxide UxOy? What is the name of the oxide? How many moles of UxOy, must have been obtained?
  2. (b) The oxide UxOy is obtained if UO2NO3 · n H2O is heated to temperatures greater than 800 °C in air. However, if you heat it gently, only the water of hydration is lost. If you have 0.865 g UO2NO3 · n H2O and obtain 0.679 g UO2NO3 on heating, how many molecules of water of hydration were there in each formula unit of the original compound?

(a)

Expert Solution
Check Mark
Interpretation Introduction

Interpretation:

A small sample of uranium metal is heated to 900oC in air to give 0.199g of a dark oxide, UxOy.  The number of moles of uranium metal has to be determined.  The empirical formula of the oxide UxOy, the name of the oxide and the number of moles of UxOy has to be determined.

Explanation of Solution

    Molar of O in the sample = UxOycompound mass-U mass                     0.199g UxOy-0.169gU=0.030gO

Find moles of uranium and oxygen in sample:

    0.169g U×1mol U238.03g U=7.10×10-4mol U0.030g O×1mol O15.9994g O=1.9×10-3mol O

Set up mole ratio:

    7.10 × 10-4mol U:1.9 × 10-3mol O

Divide all the numbers in the ratio by the smallest number of moles, 7.10 × 10-4mol U l U:2.6O.

2.6 is close to both 2.66 and 2.5, and since this number has an uncertainty of, either one is equally valid.  It is unclear whether we should round down or up to find the whole number ratio.  So, look at each case.

If the real ratio is 2:2/3, we multiply by 3, and get 3U:8O and an empirical of U3O8.

If the real ratio is ,we multiply by 2, and get 2U:5O and an empirical formula of U3O8.

Of the two empirical formula of U3O8 and U2O5, the second formula makes more sense.  The common ion of oxygen is oxide ion, O2-U3O8 looks like the sample combination of U5+and O2-.  The formula is either wrong, or contains some mixture of uranium oxides with different formulas, such as a mixture of UO3 and U2O5.  With this insight, let’s presume that the U2O5 formula is the right formula.  U2O5 would be called uranium (V) oxide.

    Molar mass of U2O5=2(238.03g/molU)+5(15.9994g/molO)=556.06g/molU2O50.199gU2O5×1molU2O5556.06gU2O5=3.58×10-4molU2O5

(b)

Expert Solution
Check Mark
Interpretation Introduction

Interpretation:

The oxide UxOy is obtained if UO2NO3.nH2O is heated to temperatures greater than 800oC in air.  If 0.865g UO2NO3.nH2O and obtain 0.679g UO2NO3 on heating, the number of molecules of water of hydration were there in each formula unit of the original compound has to be calculated.

Explanation of Solution

    Mass of H2O=0.865gUO2(NO3).nH2O-0.679g UO2(NO3)=0.186g H2O.

    Mass of H2O = 2(1.0079g/mol H)+15.9994g/mol O = 18.0152g/mol H2O.

Molar mass of UO2(NO3) = 238.03g/mol U+5(15.9994g/mol O) + 14.0067 g/mol N = 332.03g/mol UO2(NO3)

  Mol of H2O =0.186g H21mol H2O18.0152g H2O=0.0103mol H2O.

Moles of  UO2(NO3).nH2O in sample:0.679g UO2(NO31mol UO2(NO3)332.03gUO2(NO3) × 1mol UO2(NO3).nH2O1mol UO2(NO3)=0.00204molUO2(NO3).nH2O

Mole ratio:

    0.0103 mol H2O : 0.00204 mol UO2(NO3).nH2O.

Divide by the smallest number of moles, 0.00204 mol, and round to whole numbers:

    5 H2O : 1UO2(NO3).nH2O.

That means n=5, the formula is UO2(NO3).5H2O, and there are 5 molecules of water of hydration in the original hydrated compound.

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Chapter 2 Solutions

Chemistry: The Molecular Science

Ch. 2.4 - Prob. 2.6PSPCh. 2.4 - Prob. 2.6CECh. 2.4 - Prob. 2.7PSPCh. 2.4 - Prob. 2.8PSPCh. 2.5 - Prob. 2.9PSPCh. 2.5 - Prob. 2.10PSPCh. 2.6 - Prob. 2.7CECh. 2.7 - Prob. 2.8CECh. 2.7 - Prob. 2.11PSPCh. 2.7 - Prob. 2.9ECh. 2.8 - Prob. 2.12PSPCh. 2.8 - Prob. 2.10ECh. 2.9 - Prob. 2.11ECh. 2.9 - Prob. 2.12ECh. 2.9 - Prob. 2.13CECh. 2.9 - According to Table 2.10, five constitutional...Ch. 2.11 - Calculate (a) the amount of Ti atoms in 4.00 g...Ch. 2.11 - Prob. 2.15CECh. 2.11 - Prob. 2.16ECh. 2.11 - Prob. 2.17CECh. 2.11 - Prob. 2.18ECh. 2.11 - Prob. 2.19ECh. 2.11 - Prob. 2.14PSPCh. 2.11 - Prob. 2.15PSPCh. 2.11 - Prob. 2.16PSPCh. 2.11 - Prob. 2.20CECh. 2.12 - Prob. 2.17PSPCh. 2.12 - Prob. 2.18PSPCh. 2.12 - Prob. 2.21ECh. 2.12 - Hydrazine is composed of 87.42% nitrogen and...Ch. 2.12 - Prob. 2.20PSPCh. 2.12 - Prob. 2.22ECh. 2 - An isotope of an element contains 63 protons and...Ch. 2 - Prob. IISPCh. 2 - Prob. IIISPCh. 2 - Dioxathion, a pesticide, contains carbon,...Ch. 2 - Prob. 1QRTCh. 2 - Prob. 2QRTCh. 2 - Prob. 3QRTCh. 2 - Prob. 4QRTCh. 2 - Prob. 5QRTCh. 2 - Prob. 6QRTCh. 2 - Prob. 7QRTCh. 2 - Prob. 8QRTCh. 2 - Prob. 9QRTCh. 2 - Prob. 10QRTCh. 2 - Match these by placing the correct notation in the...Ch. 2 - Prob. 12QRTCh. 2 - Prob. 13QRTCh. 2 - Prob. 14QRTCh. 2 - Prob. 15QRTCh. 2 - Prob. 16QRTCh. 2 - Prob. 17QRTCh. 2 - Prob. 18QRTCh. 2 - Prob. 19QRTCh. 2 - Prob. 20QRTCh. 2 - Prob. 21QRTCh. 2 - Prob. 22QRTCh. 2 - Prob. 23QRTCh. 2 - Prob. 24QRTCh. 2 - Prob. 25QRTCh. 2 - Prob. 26QRTCh. 2 - Prob. 27QRTCh. 2 - Prob. 28QRTCh. 2 - Argon has three naturally occurring isotopes:...Ch. 2 - Prob. 30QRTCh. 2 - Prob. 31QRTCh. 2 - Prob. 32QRTCh. 2 - Prob. 33QRTCh. 2 - Prob. 34QRTCh. 2 - Prob. 35QRTCh. 2 - Prob. 36QRTCh. 2 - Prob. 37QRTCh. 2 - Prob. 38QRTCh. 2 - Prob. 39QRTCh. 2 - Prob. 40QRTCh. 2 - Prob. 41QRTCh. 2 - Prob. 42QRTCh. 2 - Prob. 43QRTCh. 2 - Prob. 44QRTCh. 2 - Prob. 45QRTCh. 2 - Prob. 46QRTCh. 2 - Prob. 47QRTCh. 2 - Prob. 48QRTCh. 2 - Prob. 49QRTCh. 2 - Prob. 50QRTCh. 2 - Prob. 51QRTCh. 2 - Prob. 52QRTCh. 2 - Prob. 53QRTCh. 2 - Prob. 54QRTCh. 2 - Prob. 55QRTCh. 2 - Prob. 56QRTCh. 2 - Prob. 57QRTCh. 2 - Prob. 58QRTCh. 2 - Prob. 59QRTCh. 2 - Prob. 60QRTCh. 2 - Prob. 61QRTCh. 2 - Prob. 62QRTCh. 2 - Prob. 63QRTCh. 2 - Prob. 64QRTCh. 2 - Prob. 65QRTCh. 2 - Prob. 66QRTCh. 2 - Prob. 67QRTCh. 2 - Prob. 68QRTCh. 2 - Prob. 69QRTCh. 2 - Prob. 70QRTCh. 2 - Prob. 71QRTCh. 2 - Prob. 72QRTCh. 2 - Prob. 73QRTCh. 2 - Prob. 74QRTCh. 2 - If you have a ring that contains 1.94 g gold,...Ch. 2 - You have a pure sample of the antiseptic...Ch. 2 - You have a pure sample of apholate, C12H24N9P3, a...Ch. 2 - Prob. 78QRTCh. 2 - Prob. 79QRTCh. 2 - Prob. 80QRTCh. 2 - Prob. 81QRTCh. 2 - Prob. 82QRTCh. 2 - Prob. 83QRTCh. 2 - Prob. 84QRTCh. 2 - Prob. 85QRTCh. 2 - Prob. 86QRTCh. 2 - Prob. 87QRTCh. 2 - Prob. 88QRTCh. 2 - Prob. 89QRTCh. 2 - Prob. 90QRTCh. 2 - Quinine (molar mass = 324.41 g/mol) is used as a...Ch. 2 - Prob. 92QRTCh. 2 - The mineral uraninite is a uranium oxide that is...Ch. 2 - Carbonic anhydrase, an important enzyme in...Ch. 2 - Nitrogen fixation in the root nodules of peas and...Ch. 2 - Disilane, Si2Hx, contains 90.28% silicon by mass....Ch. 2 - Chalky, white crystals in mineral collections are...Ch. 2 - A well-known reagent in analytical chemistry,...Ch. 2 - Prob. 99QRTCh. 2 - Prob. 100QRTCh. 2 - The density of a solution of sulfuric acid is...Ch. 2 - Prob. 102QRTCh. 2 - Prob. 103QRTCh. 2 - Prob. 104QRTCh. 2 - Prob. 105QRTCh. 2 - Prob. 106QRTCh. 2 - Prob. 107QRTCh. 2 - The Statue of Liberty in New York harbor is made...Ch. 2 - Prob. 109QRTCh. 2 - Prob. 110QRTCh. 2 - Prob. 111QRTCh. 2 - Prob. 112QRTCh. 2 - Prob. 113QRTCh. 2 - Prob. 114QRTCh. 2 - Prob. 115QRTCh. 2 - Prob. 116QRTCh. 2 - Prob. 117QRTCh. 2 - Prob. 118QRTCh. 2 - Prob. 119QRTCh. 2 - Prob. 120QRTCh. 2 - Prob. 121QRTCh. 2 - Prob. 122QRTCh. 2 - Prob. 123QRTCh. 2 - Prob. 124QRTCh. 2 - Prob. 125QRTCh. 2 - Prob. 126QRTCh. 2 - Prob. 127QRTCh. 2 - Prob. 128QRTCh. 2 - Prob. 129QRTCh. 2 - The element bromine is Br2, so the mass of a Br2...Ch. 2 - Uranium is used as a fuel, primarily in the form...Ch. 2 - Prob. 132QRTCh. 2 - Hemoglobin is an iron-containing protein (molar...Ch. 2 - There are three naturally occurring isotopes of...Ch. 2 - Prob. 135QRTCh. 2 - Prob. 136QRTCh. 2 - Prob. 137QRTCh. 2 - An adult human body contains 6.0 L blood, which...Ch. 2 - Prob. 139QRTCh. 2 - Prob. 140QRTCh. 2 - Prob. 141QRTCh. 2 - The present average concentration (mass percent)...Ch. 2 - Prob. 144QRTCh. 2 - A 4.22-g mixture of calcium chloride and sodium...Ch. 2 - A certain metal, M, forms two oxides, M2O and MO....Ch. 2 - If you heat Al with an element from Group 6A, an...Ch. 2 - Prob. 2.ACPCh. 2 - The age of the universe is unknown, but some...Ch. 2 - Prob. 2.CCPCh. 2 - Prob. 2.DCPCh. 2 - Prob. 2.ECP
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