Be sure to answer all parts. Copper has two naturally occurring isotopes, 6Cu (isotopic mass 62.9296 amu) and 65Cu (isotopic mass 64.9278 amu). If copper has an atomic mass of 63.546 amu, what is the percent abundance of each isotope? Report your answer to 5 significant figures. % 63Cu 65Cu

Be sure to answer all parts. Copper has two naturally occurring isotopes, 6Cu (isotopic mass 62.9296 amu) and 65Cu (isotopic mass 64.9278 amu). If copper has an atomic mass of 63.546 amu, what is the percent abundance of each isotope? Report your answer to 5 significant figures. % 63Cu 65Cu

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 27QRT

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Average Atomic Weight Part 1: Consider the four identical spheres below, each with a mass of 2.00 g. Calculate the average mass of a sphere in this sample. Part 2: Now consider a sample that consists of four spheres, each with a different mass: blue mass is 2.00 g, red mass is 1.75 g, green mass is 3.00 g, and yellow mass is 1.25 g. a Calculate the average mass of a sphere in this sample. b How does the average mass for a sphere in this sample compare with the average mass of the sample that consisted just of the blue spheres? How can such different samples have their averages turn out the way they did? Part 3: Consider two jars. One jar contains 100 blue spheres, and the other jar contains 25 each of red, blue, green, and yellow colors mixed together. a If you were to remove 50 blue spheres from the jar containing just the blue spheres, what would be the total mass of spheres left in the jar? (Note that the masses of the spheres are given in Part 2.) b If you were to remove 50 spheres from the jar containing the mixture (assume you get a representative distribution of colors), what would be the total mass of spheres left in the jar? c In the case of the mixture of spheres, does the average mass of the spheres necessarily represent the mass of an individual sphere in the sample? d If you had 80.0 grams of spheres from the blue sample, how many spheres would you have? e If you had 60.0 grams of spheres from the mixed-color sample, how many spheres would you have? What assumption did you make about your sample when performing this calculation? Part 4: Consider a sample that consists of three green spheres and one blue sphere. The green mass is 3.00 g, and the blue mass is 1.00 g. a Calculate the fractional abundance of each sphere in the sample. b Use the fractional abundance to calculate the average mass of the spheres in this sample. c How are the ideas developed in this Concept Exploration related to the atomic weights of the elements?
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. 21. Repeat Exercise 2.20 using an element that has three naturally occurring isotopes.
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.
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.
Three compounds containing only carbon and hydrogen are analyzed. The results for the analysis of the first two compounds are given below: Which, if any, of the following results for the mass of hydrogen in compound C follows the law of multiple proportions? (a) 5.84 g(b) 3.47 g (c) 2.72 g
A general chemistry student found a chunk of metal in the basement of a friends house. To figure out what it was, she used the ideas just developed in class about density. She measured the mass of the metal to be 175.2 grams. Then she dropped the metal into a measuring cup and found that it displaced 15.3 mL of water. Calculate the density of the metal. What element is this metal most likely to be?
Two elements, R and Q, combine to form two binary compounds. In the first compound, 14.0 g of R combines with 3.00 g of Q. In the second compound, 7.00 g of R combines with 4.50 g of Q. Show that these data are in accord with the law of multiple proportions. If the formula of the second compound is RQ, what is the formula of the first compound?
An isotope of an element contains 63 protons and 91 neutrons. (a) Identify the element and give its symbol. (b) Give the elements atomic number. (c) Give the mass number of the isotope. (d) This element has two naturally occurring isotopes. Given the information in the table, calculate the atomic weight of the element. (e) In which region of the periodic table is the element found? Explain your answer. (f) Is the element a metal, metalloid, or nonmetal? Explain your answer. (g) This element, used in compact fluorescent light bulbs and computer screens, has an atomic radius of 180 pm. Calculate how long the chain of atoms would be if all the atoms in a 1.25-mg sample of this element were put into a row.
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.
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 .
Write a chemical formula for each substance, and draw a picture of how the nanoscale particles are arranged at room temperature. Water, a liquid whose molecules contain two hydrogen atoms and one oxygen atom each Nitrogen, a gas that consists of diatomic molecules Neon Chlorine
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