Concept explainers
9 Answer true or false.
(a) Matter is divided into elements and pure substances.
(b) Matter is anything that has mass and volume (occupies space).
(C) A mixture is composed of two or more pure substances.
(d) An element is a pure substance.
(e) A heterogeneous mixture can be separated into pure substances, but a homogeneous mixture cannot.
(f) A compound consists of elements combined in a fixed ratio.
(g) A compound is a pure substance.
(h) All matter has mass.
(I) All of the 118 known elements occur naturally on Earth.
(j) The first six elements in the Periodic Table are the most important for human life.
(k) The combining ratio of a compound tells you how many atoms of each element are combined in the compound.
(I) The combining ratio of 1:2 in the compound CO2 tells you that this compound is formed by the combination of one gram of carbon with two grams of oxygen.
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Chapter 2 Solutions
Introduction To General, Organic, And Biochemistry
- Distilling a red liquid physically separates it into a red solid and a clear, colorless liquid. The red liquid is (A) an element. (B) a compound. (C) a pure substance. (D) a solution.arrow_forward(a) Atoms are very small compared to objects on the macroscopic scale. The radius of a aluminum atom is 143 pm. What is this value in meters and in centimeters? m cm (b) The mass of a single aluminum atom is 4.48×10-23 g. Suppose enough Al atoms were lined up like beads on a string to span a distance of 37.7 cm (15 inches). How many atoms would be required? atoms What mass in grams of Al would be used? g Could you weigh out this amount of aluminum using a typical laboratory balance? (c) Taking the density of aluminum metal to be 2.70 g/cm³, calculate the mass of metal needed to form a piece of Al wire with the same length as the distance in b, but with a diameter of 1.00 mm. Hint: The volume of a cylinder is n times its radius squared times its height. (V = n r² h) How many aluminum atoms does this represent? g atomsarrow_forward3. The radius of an atom of gold (Au) is about 1.35 A°. (a) Express this distance in nanometers (nm) and in picometers (pm). (b) How many gold atoms would have to be lined up to span 1.0 mm? (c) If the atom is assumed to be a sphere, what is the volume in cm3 of a single Au atom? (Note: unit A is angstrom).arrow_forward
- (b) A certain element has two naturally occurring isotopes. The mass of one of the isotopes is 106.905 amu and its natural abundance is 51.60%. The mass of the second isotope is 108.883 amu. Calculate the average atomic mass Write the chemical symbols of the isotopes (c) An organic compound consists of carbon, hydrogen and sulfur only. The percentage of carbon by mass in this compound wąs found to be 30.27%. The complete combustion of 1.367 g this compound produces 1.765 g of sulfur dioxide (SO2) (i) Determine the empirical formula for this compound. (ii) If a sample of this compound having the mass 3.781 x 103 mg contains 9.528 x 10-3 moles of the compound, determine the molecular formula.arrow_forward7. State whether each of the following represents a chemical change or merely a physical change:(a) A few grams of sucrose (table sugar) are placed in a small beaker of deionized water; the sugar crystals “disappear,” and the liquid in the beaker remains clear and colorless.(b) A copper statue, over time, turns green.(c) When a teaspoon of baking soda (sodium bicarbonate) is placed into a few ounces of vinegar (acetic acid), volumes of bubbles (effervescence) are produced.arrow_forward(a) Carbon and iron are both elements. What is an element?arrow_forward
- Chemistry (b) A sampling plan is necessary to ensure that a laboratory sample is truly a representative of the entire population. (i) Describe the goals of the sampling plan. "It is possible to determine whether the population is homogeneous or heterogeneous if a single sample is collected and analyzed." Comment on this statement. (ii)arrow_forwardMusical instruments like trumpets and trombones are madefrom an alloy called brass. Brass is composed of copper andzinc atoms and appears homogeneous under an optical microscope.The approximate composition of most brass objectsis a 2:1 ratio of copper to zinc atoms, but the exact ratio variessomewhat from one piece of brass to another. (a) Would you classify brass as an element, a compound, a homogeneousmixture, or a heterogeneous mixture? (b) Would it be correctto say that brass is a solution?arrow_forwardClassify each property as physical or chemical. (a) the tendency of copper to turn green when exposed to air(b) the tendency of automobile paint to dull over time(c) the tendency of gasoline to evaporate quickly when spilled(d) the low mass (for a given volume) of aluminum relative to other metalsarrow_forward
- (a) Under one set of conditions, the substances in A and B mix, and the result is depicted in C. Does this represent a chemical (b) Under a second set of conditions, the same substances mix, and the result is depicted in D. Does this represent a chemical (c) Under a third set of conditions, the sample depicted in C changes to that in D. Does this represent a chemical or a physical change? (d) After the change in part (c) has occurred, does the sample have different chemical properties? Physical properties? ra physical change? a physical change?arrow_forwardA metal object of an irregular shape has a mass of 31.5 grams. When the metal is added to water in a graduated cylinder, the volume of water increases from 5.28 mL to 7.61 mL. (A) How much water does the metal displace? (B) Calculate the density of the metal. (C) Is the metal made of platinum? Explain. (Hint: the density of platinum = 21.4 g/cm³)arrow_forwardWhich of the following are pure substances? Explain. (a) Calcium chloride, used to melt ice on roads, consists of two elements, calcium and chlorine, in a fixed mass ratio. (b) Sulfur consists of sulfur atoms combined into octatomic molecules. (c) Baking powder, a leavening agent, contains 26% to 30% sodium hydrogen carbonate and 30% to 35% calcium dihydrogen phosphate by mass. (d) Cytosine, a component of DNA, consists of H, C, N, and O atoms bonded in a specific arrangement.arrow_forward
- World of Chemistry, 3rd editionChemistryISBN:9781133109655Author:Steven S. Zumdahl, Susan L. Zumdahl, Donald J. DeCostePublisher:Brooks / Cole / Cengage Learning