7. If an element, “X" has two isotopes with the following masses and abundances: 46X = 45.974 amu , 24.32% abundance 38X = 38.012 amu , 75.68% abundance Calculate the relative atomic mass of the element "X"? Identify the element “X".

7. If an element, “X" has two isotopes with the following masses and abundances: 46X = 45.974 amu , 24.32% abundance 38X = 38.012 amu , 75.68% abundance Calculate the relative atomic mass of the element "X"? Identify the element “X".

Chemistry for Engineering Students

4th Edition

ISBN:9781337398909

Author:Lawrence S. Brown, Tom Holme

Publisher:Lawrence S. Brown, Tom Holme

Chapter2: Atoms And Molecules

Section: Chapter Questions

Problem 2.75PAE: 2.75 Chlorine has only two isotopes, one with mass 35 and the other with mass 37. One is present at...

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The element europium exists in nature as two isotopes: 151Eu has a mass of 150.9196 u and 153Eu has a mass of 152.9209 u. The average atomic mass of europium is 151.96 u. Calculate the relative abundance of the two europium isotopes.
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.
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.
Neon has three stable isotopes, one with a small abundance. What are the abundances of the other two isotopes? 20Ne, mass = 19.992435 u; percent abundance = ? 21Ne mass = 20.993843 u; percent abundance = 027% 22Ne mass = 21.991383 u: percent abundance = ?
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?
Europium has two stable isotopes, 151Eu and 153Eu, with masses of 150.9197 u and 152.9212 u, respectively. Calculate the percent abundances of these isotopes of europium.
There are 1.699 1022 atoms in 1.000 g of chlorine. Assume that chlorine atoms are spheres of radius 0.99 and that they are lined up side by side in a 0.5-g sample. How many miles in length is the line of chlorine atoms in the sample?
Chlorine has two isotopes, Cl-35 and Cl-37. Their abundances are 75.53% and 24.47%, respectively. Assume that the only hydrogen isotope present is H-1. (a) How many different HCI molecules are possible? (b) What is the sum of the mass numbers of the two atoms in each molecule? (c) Sketch the mass spectrum for HCI if all the positive ions are obtained by removing a single electron from an HCI molecule.
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?
The formula of water is If-O. Which of the following is indicated by this formula? Explain your answer. a. The mass of hydrogen is twice that of oxygen in each molecule. b. There are two hydrogen atoms and one oxygen atom per water molecule. c. The mass of oxygen is twice that of hydrogen in each molecule. d. There are two oxygen atoms and one hydrogen atom per water molecule.
2.74 The accompanying table provides the identity of the two naturally occurring isotopes for four elements and the atomic weights for those elements. (In each case, the two isotopes differ in mass number by two.) Which element has the mass spectrum shown? Explain your answer.
Strontium has four stable isotopes. Strontium-84 has a very low natural abundance, but 86Sr, 87Sr, and 88Sr are all reasonably abundant. Knowing that the atomic weight of strontium is 87.62, which of the more abundant isotopes predominates?