The Components of Matter

Classify each of the following as a compound, a homogeneous mixture, or a heterogeneous mixture: (a) orange juice; (b) Vegetable soup; (c) Cement; (d) Calcium sulfate; (e) tea.

Name the technique(s) and briefly describe the procedure you would use to separate each of the following mixtures into two components: (a) crushed ice and crushed glass; (b) table sugar dissolved in ethanol; (c) iron and sulfur, (d) two pigments (chlorophyll a and chlorophyll b) from spinach leaves.

A quality-control laboratory analyzes a product mixture using gas-liquid chromatography. The separation of components is more than adequate, but the process takes too long. Suggest two ways, other than changing the stationary phase, to shorten the analysis time.

Helium is the lightest noble gas and the second most abundant element (after hydrogen) in the universe.
(a) The radius of a helium atom is 3.1×10^-11 m; the radius of its nucleus is 2.5×10^-15 m. What fraction of the spherical atomic volume is occupied by the nucleus (V of a sphere =4/3 πr³)?
(b) The mass of a helium-4 atom is 6.64648X10^-24 g, and each of its two electrons has a mass of 9.10939×10^-28 g. What fraction of this atom's mass is contributed by its nucleus?

Prior to 1961, the atomic mass standard was defined as of the mass of ¹⁶O. Based on that standard: (a) What was the mass of carbon-12, given the modern atomic mass of oxygen is 15.9994 amu? (b) What was the mass of potassium-39, given its modern isotopic mass is 38.9637 amu?

From the following ions and their radii (in pm), choose a pair that gives the strongest ionic bonding and a pair that gives the weakest:

${\mathbf{Mg}}^{\mathbf{2}\mathbf{+}}\mathbf{72}\mathbf{;}\mathbf{ }{\mathbf{K}}^{\mathbf{+}}\mathbf{138}\mathbf{;}\mathbf{ }{\mathbf{Rb}}^{\mathbf{+}}\mathbf{152}\mathbf{;}\mathbf{ }{\mathbf{Ba}}^{\mathbf{2}\mathbf{+}}\mathbf{135}\mathbf{;}\mathbf{ }{\mathbf{Cl}}^{\mathbf{-}}\mathbf{181}\mathbf{;}\mathbf{ }{\mathbf{O}}^{\mathbf{2}\mathbf{-}}\mathbf{140}\mathbf{;}\mathbf{ }{\mathbf{l}}^{\mathbf{-}}\mathbf{220}$

Give the molecular mass of each compound depicted below, and provide a correct name for any that are named incorrectly.

Transition metals, located in the centre of the periodic table, have many essential uses as elements and form many important compounds as well. Calculate the molecular mass of the following transition metal compounds:
(a) [Co(NH₃)₆]Cl₃ (b) [Pt(NH₃)₄BrCl]Cl₂  (c) K₄[V(CN)₆]  (d) [Ce(NH₃)₆][FeCl₄]₃

A rock is 5.0% by mass fayalite (Fe₂SiO₄), 7.0% by mass forsterite (Mg₂SiO₄), and the remainder silicon dioxide. What is the mass percent of each element in the rock?

Polyatomic ions are named by patterns that apply to elements in a given group. Using the periodic table and Table 2.5, give the name of each of the following: 

(a) SeO₄^2-; (b) AsO₄^3-; (c) BrO₂^-; (d) HSeO4^-; (e) TeO₃^2-.

Ammonium dihydrogen phosphate, formed from the reaction of phosphoric acid with ammonia, is used as a crop fertilizer as well as a component of some fire extinguishers. (a) What are the mass percentages of N and P in the compound? (b) How much ammonia is incorporated into 100. g of compound?

Nitrogen forms more oxides than any other element. The percents by mass of N in three different nitrogen oxides are (I) 46.69%; (II) 36.85%; (III) 25.94%. (a) Determine the empirical formula of each compound. (b) How many grams of oxygen per 1.00 g of nitrogen are in each compound?

Dimercaprol ( ) was developed during World War I as an antidote to arsenic-based poison gas and is used today to treat heavy-metal poisoning. It binds the toxic element and carries it out of the body. 

(a) If each molecule binds one arsenic (As) atom, how many atoms of As could be removed by 175 mg of dimercaprol? 

(b) If one molecule binds one metal atom, calculate the mass %of each of the following metals in a metal-dimercaprol combination: mercury, thallium, chromium.

Scenes A-I depict various types of matter on the atomic scale. Choose the correct scene(s) for each of the following:
 (a) A mixture that fills its container
 (b) A substance that cannot be broken down into simpler ones
 (c) An element with very high resistance to flow
 (d) A homogeneous mixture
 (e) An element that conforms to the walls of its container and displays a surface
 (f) A gas consisting of diatomic particles
 (g) A gas that can be broken down into simpler substances
 (h) A substance with a 2/1 ratio of its component atoms
 (i) Matter that can be separated into its component substances by physical means
 (j) A heterogeneous mixture
 (k) Matter that obeys the law of definite composition

The number of atoms in $\mathbf{1}{\mathbf{dm}}^{\mathbf{3}}$ aluminium is nearly the same as the number of atoms in $\mathbf{1}{\mathbf{dm}}^{\mathbf{3}}$ lead, but the densities of these metals are very different (see Table 1.5). Explain.

The seven most abundant ions in seawater make up more than 99% by mass of the dissolved compounds. They are listed in units of mg ion/kg seawater: chloride 18,980; sodium 10,560;sulfate 2650; magnesium 1270; calcium 400; potassium 380;hydrogen carbonate 140.
 (a) What is the mass % of each ion in seawater?
 (b) What percent of the total mass of ions in sodium ions?

(c) How does the total mass % of alkaline earth metal ions compare with the total mass % of alkali metal ions?
(d) Which makes up the larger mass fraction of dissolved components, anions, or cations?

You are working in the laboratory preparing sodium chloride. Consider the following results for three preparations of the compound:
 Case 1:  $\mathbf{39}\mathbf{.}\mathbf{34}\mathbf{ }\mathbf{g}\mathbf{ }\mathbf{Na}\mathbf{+}\mathbf{60}\mathbf{.}\mathbf{66}\mathbf{ }\mathbf{g}\mathbf{ }{\mathbf{Cl}}_2\to \mathbf{100}\mathbf{.}\mathbf{00}\mathbf{ }\mathbf{g}\mathbf{ }\mathbf{NaCl}$
 Case 2:  $\mathbf{39}\mathbf{.}\mathbf{34}\mathbf{ }\mathbf{g}\mathbf{ }\mathbf{Na}\mathbf{+}\mathbf{70}\mathbf{.}\mathbf{00}\mathbf{ }\mathbf{g}\mathbf{ }{\mathbf{Cl}}_2\to \mathbf{100}\mathbf{.}\mathbf{00}\mathbf{ }\mathbf{g}\mathbf{ }\mathbf{NaCl}\mathbf{+}\mathbf{9}\mathbf{.}\mathbf{34}\mathbf{ }\mathbf{g}\mathbf{ }{\mathbf{Cl}}_2$
 Case 3:  $\mathbf{50}\mathbf{.}\mathbf{00}\mathbf{ }\mathbf{g}\mathbf{ }\mathbf{Na}\mathbf{+}\mathbf{50}\mathbf{.}\mathbf{00}\mathbf{ }\mathbf{g}\mathbf{ }{\mathbf{Cl}}_2\to \mathbf{82}\mathbf{.}\mathbf{43}\mathbf{ }\mathbf{g}\mathbf{ }\mathbf{NaCl}\mathbf{+}\mathbf{17}\mathbf{.}\mathbf{57}\mathbf{ }\mathbf{g}\mathbf{ }\mathbf{Na}$
Explain these results in terms of the laws of conservation of mass and definite composition.

The scenes below represent a mixture of two monatomic gases undergoing a reaction when heated. Which mass law(s) is(are) illustrated by this change?

When barium (Ba) reacts with sulfur (S) to form barium sulfide (BaS), each Ba atom reacts with an S atom. If 2.50 cm³ of Ba reacts with 1.75 cm³ of S, are there enough Ba atoms to react with the S atoms (d of Ba 3.51 g/cm³ ; d of S 2.07 g/cm³ )?

Succinic acid (below) is an important metabolite in biological energy production. Give the molecular formula, empirical formula, and molecular mass of succinic acid, and calculate the mass percent of each element.

Fluoride ion is poisonous in relatively low amounts: 0.2 g of F^- per 70 kg of body weight can cause death. Nevertheless, in order to prevent tooth decay, F^- ions are added to drinking water at a concentration of 1 mg of F^- ion per L of water. How many liters of fluoridated drinking water would a 70-kg person have to consume in one day to reach this toxic level? How many kilograms of sodium fluoride would be needed to treat a 8.50×10⁷ -gal reservoir?

Which of the following models represent compounds having the same empirical formula? What is the molecular mass of this common empirical formula?

Antimony has many uses, for example, in infrared devices and as part of an alloy in lead storage batteries. The element has two naturally occurring isotopes, one with a mass of 120.904 amu, and the other with mass of 122.904 amu. (a) Write the ^A_ZX notation for each isotope. (b) Use the atomic mass of antimony from the periodic table to calculate the natural abundance of each isotope.

Dinitrogen monoxide (${\mathbf{N}}_{\mathbf{2}}\mathbf{O}$; nitrous oxide) is a greenhouse gas that enters the atmosphere principally from natural fertilizer breakdown. Some studies have shown that the isotope ratios${}^{\mathbf{15}}\mathbf{N}$ of ${}^{\mathbf{14}}\mathbf{N}$ to  and of ${}^{\mathbf{18}}\mathbf{O}$ to ${}^{\mathbf{16}}\mathbf{O}$ in ${\mathbf{N}}_{\mathbf{2}}\mathbf{O}$ depending on the source, which can thus be determined by measuring the relative abundance of molecular masses in a sample of ${\mathbf{N}}_{\mathbf{2}}\mathbf{O}$. (a) What different molecular masses are possible for ${\mathbf{N}}_{\mathbf{2}}\mathbf{O}$? (b) The percent abundance of ${}^{\mathbf{14}}\mathbf{N}$ is 99.6%, and that of ${}^{\mathbf{16}}\mathbf{O}$is 99.8%. Which molecular mass of ${\mathbf{N}}_{\mathbf{2}}\mathbf{O}$ is least common, and which is most common?

Choose the box colour (s) in the periodic table below that match(es) each of the following:

(a) Four elements that are nonmetals 

(b) Two elements that are metals

(c) Three elements that are gases at room temperature 

(d) Three elements that are solid at room temperature 

(e) One pair of elements likely to form a covalent compound 

(f) Another pair of elements likely to form a covalent compound 

(g) One pair of elements likely to form an ionic compound with the formula MX 

(h) Another pair of elements likely to form an ionic compound with the formula MX 

(i) Two elements likely to form an ionic compound with the formula M₂X 

(j) Two elements likely to form an ionic compound with the formula MX₂

(k) An element that forms no compounds 

(l) A pair of elements whose compounds exhibit the law of multiple proportions 

(m) Two elements that are building blocks in biomolecules 

(n) Two elements that are macronutrients in organisms

The two isotopes of potassium with significant abundance in nature are ³⁹K (isotopic mass 38.9637 amu, 93.258%) and ⁴¹K (isotopic mass 40.9618 amu, 6.730%). Fluorine has only one naturally occurring isotope, ¹⁹F (isotopic mass 18.9984 amu). Calculate the formula mass of potassium fluoride.

Boron trifluoride is used as a catalyst in the synthesis of organic compounds. When this compound is analyzed by mass spectrometry (see Tools of the Laboratory, p. 55), several different 1+ ions form, including ions representing the whole molecule as well as molecular fragments formed by the loss of one, two, and three F atoms. Given that boron has two naturally occurring isotopes, ¹⁰B and ¹¹B, and fluorine has one, ¹⁹F, calculate the masses of all possible 1+ ions.

Nitrogen monoxide ($\mathbf{NO}$ ) is a bioactive molecule in the blood. Low   concentrations cause respiratory distress and the formation of blood clots. Doctors prescribe nitroglycerin,${\mathbf{C}}_{\mathbf{3}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{N}}_{\mathbf{3}}{\mathbf{O}}_{\mathbf{9}}$ , and isoamyl nitrate,${\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{2}}{\mathbf{CHCH}}_2{\mathbf{CH}}_{\mathbf{2}}{\mathbf{ONO}}_{\mathbf{2}}$ , to increase $\mathbf{NO}$ . If each compound releases one molecule $\mathbf{NO}$  per atom  , calculate the mass per cent of $\mathbf{NO}$ each medicine.

TNT (trinitrotoluene; below) is used as an explosive in construction. Calculate the mass of each element in 1.00 lb of TNT.

Carboxylic acids react with alcohol to form esters, which are found in all plants and animals. Some are responsible for the flavours and odours of fruits and flowers. What is the percent by mass of carbon in each of the following esters?

Nuclei differ in their stability, and some are so unstable that they undergo radioactive decay. The ratio of the number of neutrons to the number of protons (N/Z) in a nucleus correlates with its stability. Calculate the N/Z ratio for (a) ¹⁴⁴Sm; (b) ⁵⁶Fe; (c) ²⁰Ne; (d) ¹⁰⁷Ag. (e) The radioactive isotope ²³⁸U decays in a series of nuclear reactions that includes another uranium isotope, ²³⁴U, and three lead isotopes, ²¹⁴Pb, ²¹⁰Pb, and ²⁰⁶Pb. How many neutrons, protons, and electrons are in each of these five isotopes?

The anticancer drug Platinol (Cisplatin), Pt(NH₃)₂Cl₂, reacts with the cancer cell’s DNA and interferes with its growth. (a) What is the mass % of platinum (Pt) in Platinol? (b) If Pt costs \(19/g, how many grams of Platinol can be made for \)1.00 million (assume that the cost of Pt determines the cost of the drug)?

Grignard reagents, which contain a C—Mg bond, have the general formula CH₃—(CH2)_x—MgBr and are essential in the synthesis of organic compounds. 

(a) Calculate the mass percent of Mg if x = 0. 

(b) Calculate the mass percent of Mg if x = 5. 

(c) Calculate the value of x if the mass percent of Mg is 16.5%.

In a sample of any metal, spherical atoms pack closely together, but the space between them means that the density of the sample is less than that of the atoms themselves. Iridium (Ir) is one of the densest elements: 22.56 g/cm³. The atomic mass of Ir is 192.22 amu, and the mass of the nucleus is 192.18 amu. Determine the density (in g/cm³) of (a) an Ir atom and (b) an Ir nucleus. (c) How many Ir atoms placed in a row would extend 1.00 cm [radius of Ir atom = 1.36 Å; the radius of Ir nucleus = 1.5 femtometers (fm); V of a sphere =4.3πr³ ]?

Which of the following steps in an overall process involve(s) a physical change and which involve(s) a chemical change?