Concept explainers
you can use the concepts in this chapter to obtain an estimate of the number of atoms in the universe. These steps will guide you through this calculation.
a. Begin by calculating the number of atoms in the sun. Assume that the sun is pure hydrogen with a density of
b. The sun is an average-sized star, and stars are believed to compose most of the mass of the visible universe (planets are so small they can be ignored), so we can estimate the number of atoms in a galaxy by assuming that every star in the galaxy has the same number of atoms as our sun. The Milky Way galaxy is believed to contain
c. Astronomers estimate that the universe contains approximately
Our sun is one of the 100 billion stars in the Milky Way galaxy. The universe is estimated to contain about 100 billion galaxies.
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Chapter 6 Solutions
INTRODUCTORY CHEMISTRY-W/MOD.MASTERING.
- 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?arrow_forwardConsider the following data for three binary compounds of hydrogen and nitrogen: %H (by Mass) %N (by Mass) I 17.75 82.25 II 12.58 87.42 III 2.34 97.66 When 1.00 L of each gaseous compound is decomposed to its elements, the following volumes of H2(g) and N2(g) are obtained: H2(L) N2(L) I 1.50 0.50 II 2.00 1.00 III 0.50 1.50 Use these data to determine the molecular formulas of compounds I, II, and III and to determine the relative values for the atomic masses of hydrogen and nitrogen.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_forward
- A cube of sodium has length 1.25 in. How many atoms are in that cube? (Note: dNa=0.968 g/cm3.)arrow_forwardThere 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?arrow_forwardA cylindrical piece of pure copper (d=8.92g/cm2) has diameter 1.15 cm and height 4.00 inches. How many atoms are in that cylinder? (Note: the volume of a right circular cylinder of radius r and height h is V=r2 h .)arrow_forward
- There are 2.619 1022 atoms in 1.000 g of sodium. Assume that sodium atoms are spheres of radius 1.86 and that they are lined up side by side. How many miles in length is the line of sodium atoms?arrow_forwardCopper 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_forwardClick 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_forward
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