The astronaut then measures the abundance of silicon on the new planet, obtaining the following results: Abundance Mass Isotope (%) (amu) 28 Si 73.71 27.98 29 Si 14.93 28.98 30 Si 11.36 29.97 What is the atomic mass of silicon for this planet? Express your answer to two decimal places, and include the appropriate units.

The astronaut then measures the abundance of silicon on the new planet, obtaining the following results: Abundance Mass Isotope (%) (amu) 28 Si 73.71 27.98 29 Si 14.93 28.98 30 Si 11.36 29.97 What is the atomic mass of silicon for this planet? Express your answer to two decimal places, and include the appropriate units.

Chemistry: Principles and Practice

3rd Edition

ISBN:9780534420123

Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer

Publisher:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward Mercer

Chapter1: Introduction To Chemistry

Section: Chapter Questions

Problem 1.105QE: The main weapon on a military tank is a cannon that fires a blunt projectile specially designed to...

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You have two distinct gaseous compounds made from element X and element Y. The mass percents are as follows: Compound I: 30.43% X, 69.57% Y Compound II: 63.64% X, 36.36% Y In their natural standard states, element X and element Y exist as gases. (Monatomic? Diatomic? Triatomic? That is for you to determine.) When you react gas X with gas Y to make the products, you get the following data (all at the same pressure and temperature): 1. volume gas X + 2 volumes gas Y2 volumes compound I 2. volumes gas X + 1 volume gas Y2 volumes compound II Assume the simplest possible formulas for reactants and products in the chemical equations above. Then, determine the relative atomic masses of element X and element Y.
A sample of solid elemental phosphorus that is deep red in color is burned. While the phosphorus is burning, a white smoke is produced that is actually a finely divided solid that is collected. a. Have the molecules of phosphorus been changed by the process of burning? Explain your answer. b. Is the collected white solid a different substance from the phosphorus? Explain you answer. c. In terms of the number of atoms contained, how do you think the size of the molecules of the white solid compares with the size of the molecules of phosphorus? Explain your answer. d. Classify molecules of the collected white solid using the term homotatomic or heteroatomic. Explain your reasoning.
Copper: (a) Suppose you have a cube of copper metal that is 0.236 cm on a side with a mass of 0.1206 g. If you know that each copper atom (radius = 128 pm) has a mass of 1.055 1022 g (you will learn in Chapter 2 how to find the mass of one atom), how many atoms are there in this cube? What fraction of the cube is filled with atoms? (Or conversely, how much of the lattice is empty space?) Why is there empty space in the lattice? (b) Now look at the smallest, repeating unit of the crystal lattice of copper. Knowing that an edge of this cube is 361.47 pm and the density of copper is 8.960 g/cm3, calculate the number of copper atoms in this smallest, repeating unit.
The mole is the SI unit for the amount of a substance. The mass of one mole of pure table sugar is 342.3 grams. How many grams of sugar are in exactly 1/2 mole? What is the mass of 0.764 mole?
3.37 If atypical grain of sand occupies a volume of 1.3 × 10-4 cm3, what is the volume (in cm3) of 1 mole of sand (ignoring the space between grains)? What is the volume in liters?
As part of a science project, you study traffic patterns in your city at an intersection in the middle of downtown. You set up a device that counts the ears passing through this intersection for a 24-hr period during a weekday. The graph of hourly traffic looks like this. a. At what time(s) does the highest number of cars pass through die intersection? b. At what time(s) does the lowest number of cars pass through die intersection? c. Briefly describe the trend in numbers of cars over the course of die day. d. Provide a hypothesis explaining the trend in numbers of cars over the course of the day. e. Provide a possible experiment that could test your hypothesis.
The main weapon on a military tank is a cannon that fires a blunt projectile specially designed to cause a shock wave when it hits another tank. The projectile fits into a finned casing that improves its accuracy. Calculate the mass of the projectile, assuming it is a cylinder of uranium (density = 19.05 g/cm3) that is 105 mm in diameter and 30 cm in height. The volume of a cylinder is given by the equation V = r2h
What is the chief factor that determines thephysical slateof a sample of matter?
Calculate the average density of a single Al-27 atom by assuming that it is a sphere with a radius of 0.143 nm. The masses of a proton, electron, and neutron are 1.67261024g,9.10941028g, and 1.67491024g, respectively. The volume of a sphere is 4r3/3, where r is its radius. Express the answer in grams per cubic centimeter. The density of aluminum is found experimentally to be 2.70 g/cm3. What does that suggest about the packing of aluminum atoms in the metal?
On October 21, 1982, the Bureau of the Mint changed the composition of pennies (see Exercise 120). Instead of an alloy of 95% Cu and 5% Zn by mass, a core of 99.2% Zn and 0.8% Cu with a thin shell of copper was adopted. The overall composition of the new penny was 97.6% Zn and 2.4% Cu by mass. Does this account for the difference in mass among die pennies in Exercise 120? Assume the volume of the individual metals that make up each penny can be added together to give the overall volume of the penny, and assume each penny is the same size. (Density of Cu = 8.96 g/cm3; density of Zn = 7.14 g/cm3).
Some scientists think there are living things smaller than bacteria (New York Times, January 18, 2000, p. D1). Called nanobes, they are roughly cylindrical and range from 20 to 150 nm long and about 10 nm in diameter. One approach to determining whether nanobes are living is to estimate how many atoms and molecules could make up a nanobe. If the number is too small, then there would not be enough DNA, protein, and other biological molecules to carry out life processes. To test this method, estimate an upper limit for the number of atoms that could be in a nanobe. (Use a small atom, such as hydrogen.) Also estimate how many protein molecules could fit inside a nanobe. Do your estimates rule out the possibility that a nanobe could be living? Explain why or why not.