-23 An oxygen atom has a mass of 2.66 × 10 g and a glass of water has a mass of 0.050 kg. Use this information to answer the questions below. Be sure your answers have the correct number of significant digits. What is the mass of 1 mole of oxygen atoms? Round your answer to 3 significant digits. How many moles of oxygen atoms have a mass equal to the mass of a glass of water? Round your answer to 2 significant digits. U U g X

-23 An oxygen atom has a mass of 2.66 × 10 g and a glass of water has a mass of 0.050 kg. Use this information to answer the questions below. Be sure your answers have the correct number of significant digits. What is the mass of 1 mole of oxygen atoms? Round your answer to 3 significant digits. How many moles of oxygen atoms have a mass equal to the mass of a glass of water? Round your answer to 2 significant digits. U U g X

Introductory Chemistry For Today

8th Edition

ISBN:9781285644561

Author:Seager

Publisher:Seager

Chapter1: Matter, Measurements, And Calculations

Section: Chapter Questions

Problem 1.12E

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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.
A materials engineer has filed for a patent for a new alloy to be used in golf club heads. The composition by mass ranges from 25 to 31% manganese, 6.3 to 7.8% aluminum, 0.65 to 0.85% carbon, and 5.5 to 9.0% chromium, with the remainder being iron. What are the maximum and minimum percentages of iron possible in this alloy? Use Figure 2.12 to snake a prediction about how the density of this alloy would compare with that of iron; justify your prediction.
You take three compounds, each consisting of two elements (X, Y. and/or Z), and decompose them to their respective elements. To determine the relative masses of X, Y. and Z. you collect and weigh the elements, obtaining the following data: Elements in Compound Masses of Elements 1. X and Y X = 0.4 g, Y = 4.2 g 2. Y and Z Y = 1.4 g, Z = 1.0 g 3. X and Y X = 2.0 g, Y = 7.0 g a. What are the assumptions needed to solve this problem? b. What are the relative masses of X, Y. and Z? c. What are the chemical formulas of the three compounds? d. If you decompose 21 g of compound XY, how much of each element is present?
Name and give symbols for three transition metals in the fourth period. Look up each of your choices in a dictionary, a book such as The Handbook of Chemistry and Physics, or on the Internet, and make a list of their properties. Also list the uses of each element.
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?
Which of these statements are qualitative? Which are quantitative? Explain your choice in each case. (a) Sodium is a silvery-white metal. (b) Aluminum melts at 660 C. (c) Carbon makes up about 23% of the human body by mass. (d) Pure carbon occurs in different forms: graphite, diamond, and fullerenes.
Using Table 1.1, but without using your calculator, decide which has the larger mass: 20. mL butane or 20. mL bromobenzene 10. mL benzene or 1.0 mL gold 0.732 mL copper or 0.732 mL lead
Calculate the number of atoms in the universe. The following steps will guide you through this calculation: a. Planets constitute less than 1% of the total mass of the universe and can, therefore, be neglected. Stars make up most of the visible mass of the universe, so we need to determine how many atoms are in a star. Stars are primarily composed of hydrogen atoms and our Sun is an average-sized star. Calculate the number of hydrogen atoms in our Sun given that the radius of the Sun is 7108 m and its density is 1.4g/cm3. The volume of a sphere is given by V=(43)r3 (Hint: Use the volume and the density to get the mass of the Sun.) b. The average galaxy (like our own Milky Way galaxy) contains 11011 stars, and the universe contains 1109 galaxies. Calculate the number of atoms in an average galaxy and finally the number of atoms in the entire universe. c. You can hold 11023 atoms in your hand (five copper pennies constitute 1.41023 copper atoms.) How does this number compare with the number of atoms in the universe?
How would you go about finding the number of chalk molecules it takes to write your name on the board? Provide an explanation of all you would need to do and a sample calculation.
In Groups 4A-6A, there are several elements whose symbols begin with S. Name these elements, and for each one give its symbol, atomic number, group number, and period. Describe each as a metal, metalloid, or nonmetal.
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).