Which of the following figures represents (a) a pure element, (More than one picture might fit each description.)

Which of the following figures represents (b) a mixture of two elements, (More than one picture might fit each description.)

Which of the following figures represents (c) a pure compound, (More than one picture might fit each description.)

Which of the following figures represents (d) a mixture of an element and a compound? (More than one picture might fit each description.)

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?

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?

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?

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?

Is the separation method used in brewing a cup of coffee best described as distillation, filtration, or chromatography?

(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.

(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.

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?

(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?

(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?

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.

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: c. magnesium

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: a. gasoline vapor,

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (c) a hardboiled egg

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (d) sawdust.

Give the chemical symbol or name for the following elements, as appropriate: c. potassium

You are hiking in the mountains and find a shiny gold nugget. It might be the element gold, or it might be “fool’s gold,” which is a nickname for iron pyrite, FeS₂. Which of the following physical properties do you think would help determine if the shiny nugget is really gold—appearance, melting point, density, or physical state?

In the process of attempting to characterize a substance, a chemist makes the following observations: The substance is a silvery white, lustrous metal. It melts at 649 °C and boils at 1105 °C. Its density at 20 °C is 1.738 g/cm³. The substance burns in air, producing an intense white light. It reacts with chlorine to give a brittle white solid. The substance can be pounded into thin sheets or drawn into wires. It is a good conductor of electricity. Which of these characteristics are physical properties, and which are chemical properties?

(b) Which properties of zinc can you describe from the photo? Are these physical or chemical properties?

Label each of the following as either a physical process or a chemical process: b. boiling a cup of water

Label each of the following as either a physical process or a chemical process: c. pulverizing an aspirin

A match is lit and held under a cold piece of metal. The following observations are made: (a) The match burns. (b) The metal gets warmer. (c) Water condenses on the metal. (d) Soot (carbon) is deposited on the metal. Which of these occurrences are due to physical changes, and which are due to chemical changes?

For each of the following processes, would filtration, distillation, or chromatography be the most effective separation technique:

a. removing the pulp from freshly squeezed orange juice,

b. separating a food dye into its individual components,

c. desalinating seawater?

A silvery metal is put inside a beaker of water. Bubbles form on the surface of the metal and it dissolves gradually. (a) Is this an example of a chemical or a physical change?

A soccer ball is dropped out of a window on the second floor of a dormitory to the ground below. Which of the following statements is or are true?

i. The kinetic energy of the ball is greatest at the time it is dropped out the window.

ii. As the ball falls, potential energy is converted into kinetic energy.

iii. The potential energy of the ball is due to the force of gravity acting on it.

(a) Calculate the kinetic energy (in joules) of a 1200-kg automobile moving at 18 m/s.