Rubies are essentially alumina (Al2O3) with a contaminant of chromium in the form of Cr2O3. A lab-made ruby weighing 1.994g is ground, digested in hot nitric acid, and the chromium prcipitated as Cr(OH)3(s). If the mass of the Cr(OH)3 is 0.0135 g, compute the percentage of chromium in the ruby. Also compute the percentage of Cr2O3 in the ruby.

Rubies are essentially alumina (Al2O3) with a contaminant of chromium in the form of Cr2O3. A lab-made ruby weighing 1.994g is ground, digested in hot nitric acid, and the chromium prcipitated as Cr(OH)3(s). If the mass of the Cr(OH)3 is 0.0135 g, compute the percentage of chromium in the ruby. Also compute the percentage of Cr2O3 in the ruby.

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter2: Chemical Compounds

Section: Chapter Questions

Problem 143QRT: The present average concentration (mass percent) of magnesium ions in seawater is 0.13%. A chemistry...

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The present average concentration (mass percent) of magnesium ions in seawater is 0.13%. A chemistry textbook estimates that if 1.00 × 108 tons Mg were taken out of the sea each year, it would take one million years for the Mg concentration to drop to 0.12%. Do sufficient calculations to either verify or refute this statement. Assume that Earth is a sphere with a diameter of 8000 mi, 67% of which is covered by oceans to a depth of 1 mi, and that no Mg is washed back into the oceans at any time.
A sample containing Al2O3 and Na2Cr2O7.2H2O was brought into the laboratory for analysis. The analyst heated a 2.2846 gram sample of this material to 100oC for one hour, at which time only Al2O3 and Na2Cr2O7 remained. This mixture was found to weigh 2.2312 grams. Calculate the percent chromium in the sample.
7. The zirconium oxalate K,Zr(C204)3(H2C204) · H20 was synthesized by mixing 1.68 g of ZroCl2 · 8H20 with 5.20 g of H2C204 · 2H20 and an excess of aqueous KOH. After 2 months, 1.25 g of crystalline product was obtained, as well as aqueous KCl and water. Calculate the percent yield.
Cooper, Zach and Nate did this experiment dissolving 3.80 g of Cu(C2H3O2)2·H2O and adding 8.60 g NaC7H4SO3N·H2O (assume present in excess). What is the theoretical yield of the product, Cu(C7H4SO3N)2(H2O)4·2 H2O(s)? Molar Mass of Copper(II) acetate monohydrate = 199.65 g/mol Molar Mass of Sodium saccharinate monohydrate = 223.18 g/mol Molar Mass of product = 535.59 g/mol
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1. Provide the chemical formula (including brackets where appropriate) or systematic name for the following compounds. (a) gold(I) hypoiodite (b) HI(aq): (f) Ca(ClO4)2·4H2O: 2. What mass (in g) of chlorine atoms are there in a sample that consists of 5e+23 molecules of molecular chlorine? INSTRUCTIONS: Report your answer to 3 significant figures in scientific notation unless stated otherwise. DO NOT include the units in your answer.
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