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Problem 19a1
The radius of an atom of tungsten (W) is about 2.10 A . (a) Express this distance in nanometers (nm).
Problem 1a
Which of the following figures represents (a) a pure element, (More than one picture might fit each description.)
Problem 1b
Which of the following figures represents (b) a mixture of two elements, (More than one picture might fit each description.)
Problem 1c
Which of the following figures represents (c) a pure compound, (More than one picture might fit each description.)
Problem 1d
Which of the following figures represents (d) a mixture of an element and a compound? (More than one picture might fit each description.)
Problem 2
Which of the following diagrams represents a chemical change?Problem 3
Musical instruments like trumpets and trombones are made from an alloy called brass. Brass is composed of copper and zinc atoms and appears homogeneous under an optical microscope. The approximate composition of most brass objects is a 2:1 ratio of copper to zinc atoms, but the exact ratio varies somewhat from one piece of brass to another. (a) Would you classify brass as an element, a compound, a homogeneous mixture, or a heterogeneous mixture?
Problem 4ai
Consider the two spheres shown here, one made of silver and the other of aluminum. (a) What is the mass of each sphere in kg?
Problem 4aii
Consider the two spheres shown here, one made of silver and the other of aluminum. (a) What is the mass of each sphere in kg?
Problem 4d
Consider the two spheres shown here, one made of silver and the other of aluminum. (d) If you release the spheres simultaneously, they will have the same velocity when they hit the ground. Will they have the same kinetic energy? If not, which sphere will have more kinetic energy?
Problem 5
Is the separation method used in brewing a cup of coffee best described as distillation, filtration, or chromatography?
Problem 6
Identify each of the following as measurements of length, area, volume, mass, density, time, or temperature: (a) 25 ps, (b) 374.2 mg, (c) 77 K, (d) 100,000 km2, (e) 1.06 mm, (f) 16 nm2, (g) -78 °C, (h) 2.56 g>cm3, (i) 28 cm3.Problem 7a
(a) Three spheres of equal size are composed of aluminum (density = 2.70 g/cm3), silver (density = 10.49 g/cm3), and nickel (density = 8.90 g/cm3). List the spheres from lightest to heaviest.
Problem 7b
(b) Three cubes of equal mass are composed of gold (density = 19.32 g/cm3), platinum (density = 21.45 g/cm3), and lead (density = 11.35 g/cm3). List the cubes from smallest to largest.
Problem 8b
The three targets from a rifle range shown below were produced by: (A) the instructor firing a newly acquired target rifle; (B) the instructor firing his personal target rifle; and (C) a student who has fired his target rifle only a few times. (b) For the A and C results in the future to look like those in B, what needs to happen?
Problem 9a
(a) What is the length of the pencil in the following figure if the ruler reads in centimeters? How many significant figures are there in this measurement?
Problem 9b
(b) An automobile speedometer with circular scales reading both miles per hour and kilometers per hour is shown. What speed is indicated, in both units? How many significant figures are in the measurements?
Problem 10a
(a) How many significant figures should be reported for the volume of the metal bar shown here?
Problem 11
Consider the jar of jelly beans in the photo. To get an estimate of the number of beans in the jar you weigh six beans and obtain masses of 3.15, 3.12, 2.98, 3.14, 3.02, and 3.09 g. Then you weigh the jar with all the beans in it, and obtain a mass of 2082 g. The empty jar has a mass of 653 g. Based on these data, estimate the number of beans in the jar. Justify the number of significant figures you use in your estimate.Problem 12
The photo below shows a picture of an agate stone. Jack, who picked up the stone on the Lake Superior shoreline and polished it, insists that agate is a chemical compound. Ellen argues that it cannot be a compound. Discuss the relative merits of their positions.Problem 13c
Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (c) aluminium
Problem 13d
Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (d) iodine tincture.
Problem 14a
Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) milk
Problem 14b
Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (b) beer
Problem 14c
Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (c) diamond
Problem 14d
Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (d) mayonnaise.
Problem 15c
Give the chemical symbol or name for the following elements, as appropriate: (c) cobalt
Problem 16a
Give the chemical symbol or name for each of the following elements, as appropriate: (a) rhenium
Problem 17
A solid white substance A is heated strongly in the absence of air. It decomposes to form a new white substance B and a gas C. The gas has exactly the same properties as the product obtained when carbon is burned in an excess of oxygen. Based on these observations, can we determine whether solids A and B and gas C are elements or compounds?Problem 18
Zirconia, an oxide of zirconium, is often used as an affordable diamond substitute. Just like diamond, it is a colorless crystal which sparkles under sunlight. Which of the following physical properties do you think would help in differentiating between diamond and Zirconia—melting point, density, or physical state?
