Chapter 1, Problem 1.125E

How many platinum atoms are in a pure platinum ring weighing 4.32 g?

Average atomic masses listed by JUPAC are based on a study of experimental results. Bromine has two isotopes 79Br and 81Br, whose masses (78.9 183 and 80.9 163 amu) and abundances (50.69% and 49.3 1%) were determined in earlier experiments. Calculate the average atomic mass of bromine based on these experiments.

Define the term atomic weight. Why might the values of atomic weights on a planet elsewhere in the universe be different from those on earth?

Early tables of atomic weights (masses) were generated by measuring the mass of a substance that reacts with 1.00 g of oxygen. Given the following data and taking the atomic mass of hydrogen as 1.00, generate a table of relative atomic masses for oxygen, sodium, and magnesium. Element Mass That Combines with 1.00Oxygen Assumed Formula Hydrogen 0.126g HO Sodium 2.875g Nao Magnesium 1.500g Mgo

The percent by mass of nitrogen is 46.7% for a species containing only nitrogen and oxygen. Which of the following could he this species? mg src=Images/HTML_99425-8-23ALQ_image001.jpg alt="" align="top"/>

2.19 Naturally occurring uranium consists of two isotopes, whose masses and abundances are shown below: Only 235U can be used as fuel in a nuclear reactor, so uramium for use in the nuclear industry must be enriched in this isotope. If a sample of enriched uranium has an atomic weight of 235.684 amu, what percentage of 235LT is present?

The average atomic masses of some elements may vary, depending upon the sources of their ores. Naturally occurring boron consists of two isotopes with accurately known masses ( 10B, 10.0129 amu and 11B, 11.0931 amu). The actual atomic mass of boron can vary from 10.807 to 10.8 19, depending on whether the mineral source is from Turkey or the United States. Calculate the percent abundances leading to the two values of the average atomic masses of boron from these two countries.

Silversmiths are warned to limit their exposure to silver in the air to 1108 g Ag/L of air in a 40-hour week. What is the allowed exposure in terms of atoms of Ag/L/week?