Q1:Silicon has three naturally-occurring isotopes: 92.23% of 28Si, with an atomic weight of 27.9769 amu, 4.68% of 29Si, with an atomic weight of 28.9765 amu, and 3.09% of 30Si, with an atomic weight of 29.9738 amu. On the basis of these data, confirm that the average atomic weight of Si is 28.0854 amu.

Q1:Silicon has three naturally-occurring isotopes: 92.23% of 28Si, with an atomic weight of 27.9769 amu, 4.68% of 29Si, with an atomic weight of 28.9765 amu, and 3.09% of 30Si, with an atomic weight of 29.9738 amu. On the basis of these data, confirm that the average atomic weight of Si is 28.0854 amu.

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter1: The Nature Of Chemistry

Section: Chapter Questions

Problem 54QRT

See similar textbooks

Similar questions

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.
These questions concern the work of J. J. Thomson: From Thomson’s work, which particles do you think he would feel are most important in the formation of compounds (chemical changes) and why? Of the remaining two subatomic particles, which do you place second in importance for forming compounds and why? Come up with three models that explain Thomson’s findings and evaluate them. To be complete you should include Thomson’s findings.
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.
Two compounds of iron and chlorine, A and B, contain 1.270 g and 1.904 g of chlorine, respectively, for each gram of iron. Show that these amounts are in the ratio 2 : 3. Is this consistent with the law of multiple proportions? Explain.
Copper atoms. (a) What is the average mass of one copper atom? (b) Students in a college computer science class once sued the college because they were asked to calculate the cost of one atom and could not do it. But you are in a chemistry course, and you can do this. (See E. Felsenthal, Wall Street Journal, May 9, 1995.) If the cost of 2.0-mm diameter copper wire (99.9995% pure] is currently 41.70 for 7.0 g, what is the cost of one copper atom?
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?
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.
Samples of compound X, Y, and Z are analyzed, with results shown here. Compound Description Mass of Carbon Mass of Hydrogen X clear, colorless, liquid with strong odor 1.776 g 0.148 g Y clear, colorless, liquid with strong odor 1.974 g 0.329 g Z clear, colorless, liquid with strong odor 7.812 g 0.651 g Do these data provide example(s) of the law of definite proportions, the law of multiple proportions, neither, or both? What do these data tell you about compounds X, Y, and Z?
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
Each of the following statements is true, but Dalton might have had trouble explaining some of them with his atomic theory. Give explanations for the following statements. a. The space-filling models for ethyl alcohol and dimethyl ether are shown below. These two compounds have die same composition by mass (52% carbon, 13% hydrogen, and 35% oxygen), yet the two have different melting points, boiling points, and solubilities in water. b. Burning wood leaves an ash that is only a small fraction of the mass of the original wood. c. Atoms can be broken down into smaller particles. d. One sample of lithium hydride is 87.4% lithium by mass, while another sample of lithium hydride Ls 74.9% lithium by mass. However, the two samples have the same chemical properties.
2.92 A candy manufacturer makes chocolate-covered cherries. Although all of the products look roughly the same, 3% of them are missing the cherry. The mass of the candy with a cherry is 18.5 g; those missing the cherry weigh only 6.4 g. (a) How would you compute the average mass of a box of 100 of these chocolate covered cherries from this manufacturer? (b) I low is this question analogous to the determination of atomic weights?
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.