Concept explainers
Cerium is the most abundant rare earth metal. Pure cerium ignites when scratched by even a soft object. It has four known isotopes:
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Chapter 2 Solutions
Chemistry: Principles and Reactions
- 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?arrow_forwardThe 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.arrow_forwardA cube of sodium has length 1.25 in. How many atoms are in that cube? (Note: dNa=0.968 g/cm3.)arrow_forward
- An alloy of iron (54.7%), nickel (45.0%), and manganese (0.3%) has a density of 8.17 g/cm3. How many iron atoms are there in a block of alloy measuring 10.0 cm 20.0 cm 15.0 cm?arrow_forwardThe element bromine is Br2, so the mass of a Br2 molecule is the sum of the mass of its two atoms. Bromine has two isotopes. The mass spectrum of Br2 produces three peaks with relative masses of 157.836, 159.834, and 161.832, and relative heights of 6.337, 12.499. and 6.164, respectively. (a) What isotopes of bromine are present in each of the three peaks? (b) What is the mass of each bromine isotope? (c) What is the average atomic mass of bromine? (d) What is the abundance of each of the two bromine isotopes?arrow_forwardEach 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.arrow_forward
- 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.arrow_forwardThe element rhenium (Re) bas two naturally occurring isotopes, 185Re and 187Re, with an average atomic mass of 186.207 u. Rhenium is 62.60% 187Re, and the atomic mass of 187Re is 186.956 u. Calculate the mass of 185Re.arrow_forwardThe 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.arrow_forward
- 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.arrow_forwardNeon 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 = ?arrow_forwardWhen a sample of phosphorus burns in air, the compound P4O10 forms. One experiment showed that 0.744 g of phosphorus formed 1.704 g of P4O10. Use this information to determine the ratio of the atomic weights of phosphorus and oxygen (mass P/mass O). If the atomic weight of oxygen is assumed to be 16.000, calculate the atomic weight of phosphorus.arrow_forward
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