The Components of Matter

Describe the essential features of a scientific model.

Hydroxyapatite, Ca₅(PO₄)₃(OH), is the main mineral component of dental enamel, dentin, and bone, and thus has many medical uses. Coating it on metallic implants (such as titanium alloys and stainless steels) helps the body accept the implant. In the form of powder and beads, it is used to fill bone voids, which encourages natural bone to grow into the void. Hydroxyapatite is prepared by adding aqueous phosphoric acid to a dilute slurry of calcium hydroxide. (a) Write a balanced equation for this preparation. (b) What mass of hydroxyapatite could form from 100 g of 85% phosphoric acid and 100. g of calcium hydroxide?

Hydrogen-containing fuels have a “fuel value” based on their mass % H. Rank the following compounds from highest mass % H to lowest: ethane, propane, benzene, ethanol, cetyl palmitate (whale oil, C₃₂H₆₄O₂).

Convert the following descriptions into balanced equations: (a) In a gaseous reaction, hydrogen sulfide burns in oxygen to form sulfur dioxide and water vapor. (b) When crystalline potassium chlorate is heated to just above its melting point, it reacts to form two different crystalline compounds, potassium chloride and potassium perchlorate. (c) When hydrogen gas is passed over powdered iron (III) oxide, iron metal and water vapor form. (d) The combustion of gaseous ethane in air forms carbon dioxide and water vapor. (e) Iron (II) chloride is converted to iron (III) fluoride by treatment with chlorine trifluoride gas. Chlorine gas is also formed.

Isobutylene is a hydrocarbon used in the manufacture of synthetic rubber. When 0.847 g of isobutylene was analyzed by combustion analysis (see Figure 3.5), the gain in mass of the CO₂ absorber was 2.657 g and that of the H₂O absorber was 1.089 g. What is the empirical formula of isobutylene?

The multistep smelting of ferric oxide to form elemental iron occurs at high temperatures in a blast furnace. In the first step, ferric oxide reacts with carbon monoxide to form Fe₃O₄. This substance reacts with more carbon monoxide to form iron (II) oxide, which reacts with still more carbon monoxide to form molten iron. Carbon dioxide is also produced in each step. (a) Write an overall balanced equation for the iron-smelting process. (b) How many grams of carbon monoxide are required to form 45.0 metric tons of iron from ferric oxide?

Question: Two aqueous solutions contain the ions indicated below.

(a) Write balanced molecular, total ionic, and net ionic equations for the reaction that occurs when the solutions are mixed. (b) If each sphere represents 0.050 mol of ion, what mass (in g) of precipitate forms, assuming 100% reaction? (c) What is the concentration of each ion in solution after reaction?

Give the oxidation number of sulfur in the following:

$$\begin{gathered} \left(a\right)SOC{l}_2 \\ \left(b\right)H_2{S}_2 \\ \left(c\right)H_{2}S{O}_3 \\ \left(d\right)N{a}_{2}S \end{gathered}$$

The active agent in many hair bleaches is hydrogen peroxide. The amount of H₂O₂ in 14.8 g of hair bleach was determined by titration with a standard potassium permanganate solution:

$2Mn{O}_4^{-}\left(aq\right)+5H_2{O}_2\left(aq\right)+6H^{+}\left(aq\right)\to 5O_2\left(g\right)+2M{n}^{2+}\left(aq\right)+8H_{2}O\left(l\right)$

 (a) How many moles of MnO₄^- were required for the titration if 43.2mL of 0.105M KMnO₄ was needed to reach the end point?

(b) How many moles of H₂O₂ were present in the 14.8-g sample of bleach?

(c) How many grams of H₂O₂ were in the sample?

(d) What is the mass percentage of H₂O₂ in the sample?

(e) What is the reducing agent in the redox reaction?

Why do decomposition reactions typically have compounds as reactants, whereas combination and displacement reactions have one or more elements?

Give the oxidation number of arsenic in the following:

$$\begin{gathered} \left(a\right)As{H}_3 \\ \left(b\right)H_{2}As{O}_4^{-} \\ \left(c\right)AsC{l}_3 \end{gathered}$$

Give the oxidation number of phosphorus in the following:

$$\begin{gathered} \left(a\right)H_2{P}_2{O}_7^{2-} \\ \left(b\right)P{H}_4^{+} \\ \left(c\right)PC{l}_5 \end{gathered}$$

Give the oxidation number of manganese in the following:

$$\begin{gathered} \left(a\right)Mn{O}_4^{2-} \\ \left(b\right)M{n}_2{O}_3^{} \\ \left(c\right)KMn{O}_4 \end{gathered}$$

Give the oxidation number of chromium in the following:

$$\begin{gathered} \left(a\right)Cr{O}_3 \\ \left(b\right)C{r}_2{O}_7^{2-} \\ \left(c\right)C{r}_2{\left(S{O}_4\right)}_3 \end{gathered}$$

Identify the oxidizing and reducing agents in the following:

$$\begin{gathered} \left(a\right)5H_2{C}_2{O}_4\left(aq\right)+2Mn{O}_4^{-}\left(aq\right)+6H^{+}\left(aq\right)\to 2M{n}^{2+}\left(aq\right)+10C{O}_2\left(g\right)+8H_{2}O\left(l\right) \\ \left(b\right)3Cu\left(s\right)+8H^{+}\left(aq\right)+2N{O}_3^{-}\left(aq\right)\to 3C{u}^{2+}\left(aq\right)+2NO\left(g\right)+4H_{2}O\left(l\right) \end{gathered}$$

Identify the oxidizing and reducing agents in the following:

$$\begin{gathered} \left(a\right)Sn\left(s\right)+2H^{+}\left(aq\right)\to S{n}^{2+}\left(aq\right)+H_2\left(g\right) \\ \left(b\right)2H^{+}\left(aq\right)+H_2{O}_2\left(aq\right)+2F{e}^{2+}\left(aq\right)\to 2F{e}^{3+}\left(aq\right)+2H_{2}O\left(l\right) \end{gathered}$$

Identify the oxidizing and reducing agents in the following:

$\left(a\right)8H^{+}\left(aq\right)+6C{l}^{-}\left(aq\right)+Sn\left(s\right)+4N{O}_3^{-}\left(aq\right)\to SnC{l}_6^{2-}\left(aq\right)+4N{O}_2\left(g\right)+4H_{2}O\left(l\right)$

$\left(b\right)2Mn{O}_4^{-}\left(aq\right)+10C{l}^{-}\left(aq\right)+16H^{+}\left(aq\right)\to 5C{l}_2^{}\left(g\right)+2M{n}^{2+}\left(aq\right)+8H_{2}O\left(l\right)$

What types of substances are most likely to be soluble in water?

How many grams of chlorine gas can be produced from the electrolytic decomposition of 874 g of calcium chloride? Name and calculate the mass (in g) of the other product.

Is ${\mathbf{S}}^{\mathbf{2}\mathbf{-}}$ larger or smaller than ${\mathbf{Cl}}^{\mathbf{-}}$ ? Is ${\mathbf{Mg}}^{\mathbf{2}\mathbf{+}}$ larger or smaller than ${\mathbf{Na}}^{\mathbf{+}}$? Explain.

Use Lewis structures to determine which two of the following are unstable: (a) ${\mathbf{SF}}_2^{}$ ; (b) ${\mathbf{SF}}_3^{}$  (c)   ${\mathbf{SF}}_4^{}$(d)  ${\mathbf{SF}}_5^{}$; (e).${\mathbf{SF}}_6^{}$

Glyphosate (below) is a common herbicide that is relatively harmless to animals but deadly to most plants. Describe the shape around and the hybridization of the P, N, and three numbered C atoms.

Molecular nitrogen, carbon monoxide, and cyanide ion are isoelectronic.

a) Draw an MO diagram for each.

b)  $\mathbf{CO}$and${\mathbf{CN}}^{-}$ are toxic. What property may explain why${\mathbf{N}}_2$   isn’t? 

The density of solid gallium at its melting point is  $\mathbf{5}\mathbf{.}\mathbf{9}\mathbf{g}\mathbf{/}{\mathbf{cm}}^3$, whereas that of liquid gallium is  $\mathbf{6}\mathbf{.}\mathbf{1}\mathbf{g}\mathbf{/}{\mathbf{cm}}^{\mathbf{3}}$. Is the temperature at the triple point higher or lower than the normal melting point? Is the slope of the solid-liquid line for gallium positive or negative?

The $\mathbf{∆}{\mathit{H}}_{\mathbf{f}}\mathbf{°}$ of gaseous dimethyl ether ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{OCH}}_{\mathbf{3}}$  is -185.4 kJ/mol; the vapor pressure is 1.00 atm at  $\mathbf{-}\mathbf{23}\mathbf{.}\mathbf{7}\mathbf{°}\mathbf{C}$ and 0.526 atm at $\mathbf{-}\mathbf{37}\mathbf{.}\mathbf{8}\mathbf{°}\mathbf{C}$. 

(a) Calculate $\mathbf{∆}{\mathit{H}}_{\mathbf{v}\mathbf{a}\mathbf{p}}^{\mathbf{°}}$  of dimethyl ether. 

(b) Calculate  $\mathbf{∆}{\mathit{H}}_{\mathbf{f}}^{\mathbf{°}}$ of liquid dimethyl ether.

Substance A has the following properties. 

$$\begin{gathered} \mathbf{mp}\mathbf{ }\mathbf{at}\mathbf{ }\mathbf{1}\mathbf{atm}\mathbf{:}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{-}\mathbf{20}\mathbf{.}\mathbf{°}\mathbf{C}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{bp}\mathbf{ }\mathbf{at}\mathbf{ }\mathbf{1}\mathbf{ }\mathbf{atm}\mathbf{:}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{85}\mathbf{°}\mathbf{C} \\ \mathbf{∆}{\mathbf{H}}_{\mathbf{fus}}\mathbf{:}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{180}\mathbf{.}\mathbf{ }\mathbf{J}\mathbf{/}\mathbf{g}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{∆}{\mathbf{H}}_{\mathbf{vap}}\mathbf{:}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{500}\mathbf{.}\mathbf{ }\mathbf{J}\mathbf{/}\mathbf{g} \\ {\mathbf{c}}_{\mathbf{solid}}\mathbf{:}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{1}\mathbf{.}\mathbf{0}\mathbf{ }\mathbf{J}\mathbf{/}\mathbf{g}\mathbf{·}\mathbf{°}\mathbf{C}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }{\mathbf{c}}_{\mathbf{liquid}}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{2}\mathbf{.}\mathbf{5}\mathbf{ }\mathbf{J}\mathbf{/}\mathbf{g}\mathbf{·}\mathbf{°}\mathbf{C} \\ {\mathbf{c}}_{\mathbf{gas}}\mathbf{:}\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{0}\mathbf{.}\mathbf{5}\mathbf{ }\mathbf{J}\mathbf{/}\mathbf{g}\mathbf{·}\mathbf{°}\mathbf{C} \end{gathered}$$

At 1 atm, a 25-g sample of A is heated from  $\mathbf{-}\mathbf{40}\mathbf{.}\mathbf{°}\mathbf{C}$ to $\mathbf{100}\mathbf{.}\mathbf{°}\mathbf{C}$  at a constant rate of 450.0 J/min.

(a) How many minutes does it take to heat the sample to its melting point? 

(b) How many minutes does it take to melt the sample? 

(c) Perform any other necessary calculations, and draw a curve of temperature vs. time for the entire heating process.

Argon makes up 0.93% by volume of air. Calculate its solubility (mol/L) in water at $\mathbf{20}\mathbf{°}\mathbf{C}$ and 1.0 atm. The Henry’s law constant for Ar under these conditions is  $\mathbf{1}\mathbf{.}\mathbf{5}\mathbf{\times }{\mathbf{10}}^{\mathbf{-}\mathbf{3}}\mathbf{ }\mathbf{mol}\mathbf{/}\mathbf{L}\mathbf{·}\mathbf{atm}$.

In a study designed to prepare new gasoline-resistant coatings, a polymer chemist dissolves 6.053 g of poly (vinyl alcohol) in enough water to make 100.0mL of solution. At ,${25}^{\circ }C$the osmotic pressure of this solution is 0.272 atm. What is the molar mass of polymer sample?

is the fluid inside a bacterial cell considered a solution, a colloid or both? Explain.

An aqueous solution is 10% glucose by mass $(d=1.039g/mLat{20}^{o}C)$. Calculate its freezing point, boiling point at 1atm, and osmotic pressure.

Four 0.50 m aqueous solutions are depicted below. Assume the solutions behave ideally:

1. Which has the highest boiling point?
2. Which has the lowest freezing point?
3. Can you determine which one has the highest osmotic pressure? Explain.

Thermal pollution from industrial wastewater causes the temperature of river or lake water to increase, which can affect fish survival as the concentration of dissolved O₂. decreases. Use the following data to find the molarity of O₂ at each temperature (assume the solution density is the same as water): 

Temperature (${}^{\circ }C$)      solubility of O₂(mg/kgH₂O)        density of H₂O (g/mL) 

Pyridine (right) is an essential portion of many biologically active compounds, such as nicotine and vitamin B6. Like ammonia, it has a nitrogen with a lone pair, which makes it act as a weak base. Because it is miscible in a wide range of solvents, from water to benzene, pyridine is one of the most important bases and solvents in organic syntheses. Account for its solubility behaviour in terms of intermolecular forces.

A chemist is studying small organic compounds for their potential use as an antifreeze. When 0.243 g of a compound is dissolved in 25.0 mL of water, the freezing point of the solution is $\mathbf{-}\mathbf{0}\mathbf{.}{\mathbf{201}}^{\mathbf{o}}\mathit{C}\mathbf{.}$

1. Calculate the molar mass of the compound (d of water 1.00 g/mL).
2. Analysis shows that the compound is 53.31 mass % C and 11.18 mass % H, the remainder being O. Calculate the empirical and molecular formulas of the compound.
3. Draw a Lewis structure for a compound with this formula that forms H bonds and another for one that does not.

Air in a smoky bar contains $4.0\times {10}^{-6}mol/L$of CO. What mass of CO is inhaled by a bartender who respires at a rate of 11 L/min during an 8.0-h shift?

Three gaseous mixtures of N₂(blue), Cl₂(green), and Ne (purple) are depicted below.

1. Which has the smallest mole fraction of N₂?
2. Which have the same mole fraction of Ne?
3. Rank all three in order of increasing mole fraction of Cl₂.

Semiconductors made from elements in Groups 3A(13) and 5A(15) are typically prepared by direct reaction of the elements at high temperature. An engineer treats 32.5 g of molten gallium with 20.4 L of white phosphorus vapor at 515 K and 195 kPa. If purification losses are 7.2% by mass, how many grams of gallium phosphide will be prepared?

Rank the halogens $C{l}_2$,$B{r}_2$,$I_2$ , and in order of increasing oxidizing strength based on their products with metallic Re: $ReC{l}_6$,$ReB{r}_5$ ,$Re{I}_4$ . Explain your ranking

Give the name and symbol or formula of a Group 7A(17) element or compound that fits each description or use:

 (a) Used in etching glass

 (b) Naturally occurring source (ore) of fluorine

 (c) Oxide used in bleaching paper pulp and textiles

 (d) Weakest hydrohalic acid

 (e) Compound used to prevent goiter (thyroid disorder) 

(f) Element that is produced in the largest quantity

 (g) Organic chloride used to make plastics

Rank the following acids in order of increasing acid strength: HClO, $HCl{O}_2$ , HBrO, HIO

Complete and balance the following equations. If no reaction occurs, write NR

(a) $H_{3}P{O}_4\left(l\right)+NaI\left(s\right)\to$ 

 (b)  $C{l}_2\left(g\right)+I^{-}\left(aq\right)\to$

(c) $B{r}_2\left(l\right)+C{l}^{-}\left(aq\right)\to$

(d)   $ClF\left(g\right)+F_2\left(g\right)\to$

How many electrons does a halogen atom need to complete its octet? Give examples of the ways a Cl atom can do so.

(a) A halogen  $\left(X_2\right)$ disproportionates in base in several steps to $X^{-}$  and $X{O}_3^{-}$ . Write the overall equation for the disproportionation of $B{r}_2$  to $B{r}^{-}$  and $Br{O}_3^{-}$ . (b) Write a balanced equation for the reaction of $Cl{F}_5$  with aqueous base (see the reaction of $Br{F}_5$  shown on p. 614).

Fill in each blank with a general formula for the type of compound formed:

Of the three significant organic reactions, which do not occur readily with benzene? Why?

Why does the C=O group react differently from the C=C group? Show an example of the difference.

Many substitution reactions involve an initial electrostatic attraction between reactants. Show where this attraction arises in the formation of an amide from an amine and an ester

Although both carboxylic acids and alcohols contain an —OH group, one is acidic in water, and the other is not. Explain

What reaction type is common to the formation of esters and acid anhydrides? What is the other product?

Both alcohols and carboxylic acids undergo substitution, but the processes are very different. Explain