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13.11.2020 • 

Chemistry

There are two isotopes of an unknown element, X-19 and X-21. The abundance of X-19 is 12.01%. A weighted average uses the percentages of each isotope to scale their contribution to the total mass. Each isotope's contribution is the percentage (in decimal form) multiplied by the mass of the isotope. What is the contribution (in amu) to the weighted average from the X-19 isotope, which has a mass of 19.00 amu?

Ответ:

KevinReed6444

15.05.2020

Chemistry

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2.14 × 10²² atoms Si

General Formulas and Concepts:

Atomic Structure

Reading a Periodic TableMoles

Stoichiometry

Using Dimensional Analysis

Explanation:

Step 1: Define

Identify

[Given] 0.0356 mol Si

[Solve] atoms Si

Step 2: Identify Conversions

Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Step 3: Convert

[DA] Set up:                                                                                                       [DA] Multiply [Cancel out units]:                                                                        

Step 4: Check

Follow sig fig rules and round. We are given 3 sig figs.

2.14383 × 10²² atoms Si ≈ 2.14 × 10²² atoms Si

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