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Chapter 2: Problem 32

Rubidium has two naturally occurring isotopes, rubidium- 85 (atomic mass \(=84.9118\) amu; abundance \(=72.15 \%)\) and rubidium- 87 (atomic mass \(=86.9092\) amu; abundance = \(27.85 \%) .\) Calculate the atomic weight of rubidium.

Short Answer

Expert verified
The atomic weight of rubidium is approximately 85.4275 amu, calculated using the atomic weight formula with the given isotope fractions and atomic masses.

Step by step solution

01

Convert abundance percentages to fractions

First, we need to convert the given abundance percentages for each isotope into fractions. For rubidium-85, we have 72.15% abundance, which is equivalent to 0.7215 as a fraction. For rubidium-87, we have 27.85% abundance, which is equivalent to 0.2785 as a fraction.
02

Extract the given atomic masses of the isotopes

Next, we extract the given atomic masses for each of the isotopes. For rubidium-85, the given atomic mass is 84.9118 amu, and for rubidium-87, the given atomic mass is 86.9092 amu.
03

Apply the atomic weight formula

Now, we will use the fractions and atomic masses obtained in the previous steps to calculate the atomic weight of rubidium. We will plug these values into the atomic weight formula: Atomic Weight = (Fraction of isotope 1)(Mass of isotope 1) + (Fraction of isotope 2)(Mass of isotope 2) Atomic Weight = (0.7215)(84.9118 amu) + (0.2785)(86.9092 amu)
04

Calculate the atomic weight

Now it's time to perform the calculations: Atomic Weight = (0.7215 * 84.9118 amu) + (0.2785 * 86.9092 amu) Atomic Weight ≈ 61.2351 amu + 24.1924 amu Atomic Weight ≈ 85.4275 amu The atomic weight of rubidium is approximately 85.4275 amu.

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Most popular questions from this chapter

Write the chemical formulas for the following compounds: (a) aluminum hydroxide, (b) potassium sulfate, (c) copper(I) oxide, (d) zinc nitrate, (e) mercury(II) bromide, (f) iron(III) carbonate, \((\mathrm{g})\) sodium hypobromite.

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