INTERACTIVE EXAMPLE The Average Mass of an Element = When a sample of natural silver is vaporized and injected into a mass spectrometer, the results are shown in the figure here. Ag-107 is present in 51.84% abundance. Ag-109 is present in 48.16% abundance. The masses of these two isotopes are Ag-107 = 106.91 u and Ag-109 108.90 u. Use this information to compute the average mass of silver. Percent Abundance -100 60 40 -20 51.84 107 Atomic Mass 109 u Submit Show Tutor Steps

INTERACTIVE EXAMPLE The Average Mass of an Element = When a sample of natural silver is vaporized and injected into a mass spectrometer, the results are shown in the figure here. Ag-107 is present in 51.84% abundance. Ag-109 is present in 48.16% abundance. The masses of these two isotopes are Ag-107 = 106.91 u and Ag-109 108.90 u. Use this information to compute the average mass of silver. Percent Abundance -100 60 40 -20 51.84 107 Atomic Mass 109 u Submit Show Tutor Steps

Chemistry & Chemical Reactivity

10th Edition

ISBN:9781337399074

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter2: Atoms Molecules And Ions

Section: Chapter Questions

Problem 105GQ: Copper atoms. (a) What is the average mass of one copper atom? (b) Students in a college computer...

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Reference Section 5-2 to find the atomic masses of 12C and 13C, the relative abundance of 12C and 13C in natural carbon, and the average mass (in u) of a carbon atom. If you had a sample of natural carbon containing exactly 10,000 atoms, determine the number of 12C and 13C atoms present. What would be the average mass (in u) and the total mass (in u) of the carbon atoms in this 10,000-atom sample? If you had a sample of natural carbon containing 6.0221 1023 atoms, determine the number of 12C and 13C atoms present What would be the average mass (in u) and the total mass (in u) of this 6.0221 1023 atom sample? Given that 1 g = 6.0221 1023 u, what is the total mass of I mole of natural carbon in units of grams?
Several samples of methane gas, the primary component of natural gas, are decomposed into carbon and hydrogen. The masses of the carbon and hydrogen are then weighed, and the results are tabulated as shown here. Which of these does not follow the law of constant composition? a. 4.0 grams hydrogen and 12.0 grams carbon b. 1.5 grams hydrogen and 4.5 grams carbon c. 7.0 grams hydrogen and 17.0 grams carbon d. 10 grams hydrogen and 30 grams carbon
The early alchemists used to do an experiment in which water was boiled for several days in a sealed glass container. Eventually. some solid residue would appear in die bottom of the flask, which was interpreted to mean that some of the water in the flask had been converted into earth. When Lavoisier repeated this experiment, he found that the water weighed the same before and after heating, and the mass of die flask plus the solid residue equaled the original mass of the flask. Were the alchemists correct? Explain what really happened. (This experiment is described in the article by A. F. Scott in Scientific American, January 1984.)
Constant Composition of Compounds Two samples of sugar are decomposed into their constituent elements. One sample of sugar produces 18.0 g carbon, 3.0 g hydrogen, and 24.0 g oxygen; the other sample produces 24.0 g carbon, 4.0 g hydrogen, and 32.0 g oxygen. Find the ratio of carbon to hydrogen and the ratio of oxygen to hydrogen for each of the samples, and show they are consistent with the law of constant composition.
A materials engineer has filed for a patent for a new alloy to be used in golf club heads. The composition by mass ranges from 25 to 31% manganese, 6.3 to 7.8% aluminum, 0.65 to 0.85% carbon, and 5.5 to 9.0% chromium, with the remainder being iron. What are the maximum and minimum percentages of iron possible in this alloy? Use Figure 2.12 to snake a prediction about how the density of this alloy would compare with that of iron; justify your prediction.
Classify the following as compounds or elements: a silver bromide used in photography; b calcium carbonate limestone; c sodium hydroxide lye; d uranium; e tin; f titanium.
Click on the site (http://openstaxcollege.org/l/16PhetAtomMass) and select the Mix Isotopes tab, hide the Percent Composition and Average Atomic Mass boxes, and then select the element boron. Write the symbols of the isotopes of boron that are shown as naturally occurring in significant amounts. Predict the relative amounts (percentages) of these boron isotopes found in nature. Explain the reasoning behind your choice. Add isotopes to the black box to make a mixture that matches your prediction in (b). You may drag isotopes from their bins or click on More and then move the sliders to the appropriate amounts. Reveal the Percent Composition and Average Atomic Mass boxes. How well does your mixture match with your prediction? If necessary, adjust the isotope amounts to match your prediction. Select Nature’s mix of isotopes and compare it to your prediction. How well does your prediction compare with the naturally occurring mixture? Explain. If necessary, adjust your amounts to make them match Nature’s amounts as closely as possible.
Calculate the number of atoms in the universe. The following steps will guide you through this calculation: a. Planets constitute less than 1% of the total mass of the universe and can, therefore, be neglected. Stars make up most of the visible mass of the universe, so we need to determine how many atoms are in a star. Stars are primarily composed of hydrogen atoms and our Sun is an average-sized star. Calculate the number of hydrogen atoms in our Sun given that the radius of the Sun is 7108 m and its density is 1.4g/cm3. The volume of a sphere is given by V=(43)r3 (Hint: Use the volume and the density to get the mass of the Sun.) b. The average galaxy (like our own Milky Way galaxy) contains 11011 stars, and the universe contains 1109 galaxies. Calculate the number of atoms in an average galaxy and finally the number of atoms in the entire universe. c. You can hold 11023 atoms in your hand (five copper pennies constitute 1.41023 copper atoms.) How does this number compare with the number of atoms in the universe?
The density of gold, Au, is 19.32 g/cm3. What is the volume (in cubic centimeters) of a piece of gold that contains 2.6 × 1024 atoms?
In a neutron star, gravity causes the electrons to combine with protons to form neutrons. A typical neutron star has a mass half that of the sun, compressed into a sphere of radius 20 km. If such a neutron star contains 6.01056 neutrons, calculate its density in grams per cubic centimeter. Compare this with the density inside a 232Th nucleus, in which 142 neutrons and 90 protons occupy a sphere of radius 9.11013cm . Take the mass of a neutron to be 1.6751024g and that of a proton to be 1.6731024g .
You perform a chemical reaction using the hypothetical elements A and B. These elements are represented by their molecular models shown below: The product of the reaction represented by molecular models is a Using the molecular models and the boxes, present a balanced chemical equation for the reaction of elements A and B. b Using the symbols A and B2 for the chemical reaction, write a balanced chemical equation. c What are some real-element possibilities for element B?
The element europium exists in nature as two isotopes: 151Eu has a mass of 150.9196 amu, and 153Eu has a mass of 152.9209 amu. The average atomic mass of europium is 151.96 amu. a. Calculate the relative abundance of the two europium isotopes. b. Graph each fractional abundance value as a y-axis value in association with its corresponding mass value on the x-axis. Starting from each x-axis value, where y = 0, draw a vertical line up to the fractional abundance value. The result will approximate the type of visual graph a mass spectrometer would yield for europium in the 150155 amu range.