109 年 國立高雄大學化學工程及材料工程學系碩士班甲組《普通化學》

The element lithium (Li) exists as two stable isotopes, $^6$Li (isotopic mass = 6.200 amu) and $^7$Li (isotopic mass = 7.200 amu). Lithium has an atomic mass of 7.125 amu. What is the percent abundance of $^6$Li?
(A) 7.5%
(B) 22.3%
(C) 90.2%
(D) 92.5%
(E) none of these

A chemical engineer dilutes a stock solution of hydrochloric acid (HCl) by adding 25.0 m³ of 7.50 M acid to enough water to make 500 m³. What is the mass (in g) of HCl per liter of the diluted solution? (Mw(HCl) = 36.46 g/mol)
(A) 13.7
(B) 12.1
(C) 0.567
(D) 0.0136
(E) none of these

A rigid plastic container holds 45.5 g of methane (CH4) at a pressure of 820 torr. What is the pressure (torr) if 3.5 g of methane is removed at constant temperature?
(A) 723
(B) 757
(C) 808
(D) 794
(E) none of these

Which of the following statements is true?
(A) The number of neutrons is the same for all neutral atoms of an element.
(B) Alkali metals form ions with a 2+ charge when they react with nonmetals.
(C) The molecule SO2 has two resonance structures.
(D) The total energy of the universe decreases, while the entropy decreases.
(E) none of these

In a hydrogenation reaction, ethene (C2H4) and H2 from ethane (C2H6). If 137 kJ is given off per mole of C2H4 reacting, how much heat (kJ) is released when 12.6 g of C2H6 forms? (Mw(C2H6) = 30.07 g/mol)
(A) 57.4
(B) 28.7
(C) 14.4
(D) 0
(E) none of these

Balance the following redox equation using the smallest integers possible and select the correct coefficient for the HI.
K2Cr2O7(aq) + HI(aq) → KI(aq) + CrI3(aq) + I2(s) + H2O(l)
(A) 1
(B) 2
(C) 4
(D) 7
(E) none of these

Which of the following statements is incorrect?

(A) $\mathrm{NF_3}$ is a polar molecule.
(B) The hybridization of the central atom is $sp^3$ in $\mathrm{ICl_4^-}$.
(C) According to the molecular orbital model, the bond order of $\mathrm{P_2}$ molecule is three.
(D) A material is made from Al, Ga, and As. The mole fraction of each element is 0.25, 0.26, and 0.49, respectively. This material would be a p-type semiconductor.
(E) none of these

Which of the following electron configurations belongs to an atom that is most likely to be involved in a covalent bond?

(A) $1s^22s^22p^63s^2$
(B) $1s^22s^22p^63s^23p^3$
(C) $1s^22s^22p^6$
(D) $1s^22s^22p^63s^23p^6$
(E) none of these

Select the correct name for the following compound.

$\mathrm{CH_3CH_2CH(CH_3)CH(CH_3)CH_2OH}$

(A) 3-ethyl-2,3-dimethyl-1-propanol
(B) 2,3,4-trimethyl-1-butanol
(C) 2,3-dimethyl-1-pentanol
(D) 3,4-dimethyl-5-pentanol
(E) none of these

A certain gas expands in volume from $1.0\ \mathrm{L}$ to $2.0\ \mathrm{L}$ at constant temperature. Calculate the work done by the gas if it expands against a vacuum. ($1\ \mathrm{L\cdot atm}=101.3\ \mathrm{J}$)

(A) $+202.6\ \mathrm{J}$
(B) $-101.3\ \mathrm{J}$
(C) $+101.3\ \mathrm{J}$
(D) $0\ \mathrm{J}$
(E) none of these

Which of the following statements about voltaic (galvanic) and electrolytic cells is correct?

(A) The anode will definitely gain weight in a voltaic cell.
(B) Oxidation occurs at the cathode of both cells.
(C) The free energy change, $\Delta G$, is negative for the voltaic cell.
(D) The electrons in the external wire flow from cathode to anode in an electrolytic cell.
(E) none of these.

Calculate $E^\circ_{\mathrm{cell}}$ and indicate whether the overall reaction shown is spontaneous or nonspontaneous.

$\mathrm{O_2(g)+4H^+(aq)+4e^-\rightarrow 2H_2O(l)} \qquad E^\circ=1.229\ \mathrm{V}$

$\mathrm{Al^{3+}(aq)+3e^-\rightarrow Al(s)} \qquad E^\circ=-1.662\ \mathrm{V}$

Overall reaction:

$\mathrm{4Al(s)+3O_2(g)+12H^+(aq)\rightarrow 4Al^{3+}(aq)+6H_2O(l)}$

(A) $E^\circ_{\mathrm{cell}}=-2.891\ \mathrm{V}$, nonspontaneous
(B) $E^\circ_{\mathrm{cell}}=-2.891\ \mathrm{V}$, spontaneous
(C) $E^\circ_{\mathrm{cell}}=2.891\ \mathrm{V}$, nonspontaneous
(D) $E^\circ_{\mathrm{cell}}=2.891\ \mathrm{V}$, spontaneous
(E) none of these

Formic acid ($\mathrm{HCOOH}$) has a $K_a=1.8\times10^{-4}$. What is the $[\mathrm{H_3O^+}]$ in a solution that is initially $0.10\ \mathrm{M}$ formic acid?

(A) $4.2\times10^{-3}\ \mathrm{M}$
(B) $8.4\times10^{-3}\ \mathrm{M}$
(C) $1.8\times10^{-4}\ \mathrm{M}$
(D) $1.8\times10^{-5}\ \mathrm{M}$
(E) none of these

When a weak acid is titrated with a strong base, the pH at the equivalence point

(A) is less than 7.0.
(B) is equal to 7.0.
(C) is greater than 7.0.
(D) is equal to the $pK_a$ of the acid.
(E) none of these

What elements are alloyed to make stainless steel?

(A) Fe and C
(B) Fe and Mn
(C) Fe and Zn
(D) Fe, V, and Zn
(E) Fe, Cr, and Ni

$30.0\ \mathrm{mL}$ of a $0.100\ \mathrm{mol/L}$ solution of a metal ion $\mathrm{M^{2+}}$ is mixed with $30.0\ \mathrm{mL}$ of a $0.100\ \mathrm{mol/L}$ solution of a ligand $\mathrm{L}$. A reaction occurs in which the product is $\mathrm{ML_4^{2+}}$. Approximately, what is the maximum concentration of $\mathrm{ML_4^{2+}}$, in $\mathrm{mol/L}$, which could result from this reaction?

(A) $0.0250$
(B) $0.250$
(C) $0.180$
(D) $0.0125$
(E) none of these

Which one of the following statements about solid Cu (face-centered cubic unit cell) is incorrect?

(A) The solid has a cubic closest-packed structure.
(B) The number of atoms surrounding each Cu atom is 12.
(C) There are two atoms per unit cell.
(D) The length of a face diagonal is four times the Cu radius.
(E) none of these

What is the molecular shape of $\mathrm{BrF_5}$ as predicted by the VSEPR theory?

(A) Trigonal bipyramidal
(B) Square planar
(C) T shaped
(D) Seesaw
(E) none of these

The rate expression for a particular reaction is $\mathrm{rate}=k[\mathrm{A}]^2[\mathrm{B}]$. If the initial concentration of B is increased from $0.1\ \mathrm{M}$ to $0.4\ \mathrm{M}$, the initial rate will increase by which of the following factors?

(A) 2
(B) 4
(C) 8
(D) 16
(E) none of these

For the reaction $\mathrm{FeCl_2(aq)+O_2(g)\rightarrow Fe_2O_3(s)+Cl_2(g)}$ (unbalanced), what volume (mL) of a $1.25\ \mathrm{M}$ solution of $\mathrm{FeCl_2}$ is required to react completely with $4.32\times10^{22}$ molecules of $\mathrm{O_2}$?

(A) 76.5
(B) 38.3
(C) 125.2
(D) 57.4
(E) none of these

For the process $\mathrm{Br_2(l)\rightarrow Br_2(g)}$, $\Delta H^\circ=31.0\ \mathrm{kJ/mol}$ and $\Delta S^\circ=93.0\ \mathrm{J/(K\cdot mol)}$. What is the normal boiling point (K) of liquid $\mathrm{Br_2}$?

Find the solubility of solid $\mathrm{CaF_2}$ ($K_{sp}=4.0\times10^{-11}$) in a $0.025\ \mathrm{M}$ $\mathrm{NaF}$ solution.

Methane ($\mathrm{CH_4}$) reacts with chlorine gas ($\mathrm{Cl_2}$) to form chloromethane ($\mathrm{CH_3Cl}$), as shown in the following equation:

$\mathrm{CH_4(g)+Cl_2(g)\rightarrow CH_3Cl(g)+HCl(g)}$

When $20.5\ \mathrm{g}$ of methane and $45.0\ \mathrm{g}$ of chlorine gas undergo a reaction that has a $65\%$ yield, what mass of chloromethane ($\mathrm{CH_3Cl}$) forms?

$M_w(\mathrm{CH_4})=16.04\ \mathrm{g/mol}$, $M_w(\mathrm{Cl_2})=70.90\ \mathrm{g/mol}$, $M_w(\mathrm{CH_3Cl})=50.48\ \mathrm{g/mol}$

Given the following reactions of nitrogen oxides and their standard enthalpy changes:

(1) $\mathrm{NO(g)+NO_2(g)\rightarrow N_2O_3(g)}$, $\Delta H^\circ_{\mathrm{rxn}}=-39.8\ \mathrm{kJ}$

(2) $\mathrm{NO(g)+NO_2(g)+O_2(g)\rightarrow N_2O_5(g)}$, $\Delta H^\circ_{\mathrm{rxn}}=-112.5\ \mathrm{kJ}$

(3) $\mathrm{2NO_2(g)\rightarrow N_2O_4(g)}$, $\Delta H^\circ_{\mathrm{rxn}}=-57.2\ \mathrm{kJ}$

(4) $\mathrm{2NO(g)+O_2(g)\rightarrow 2NO_2(g)}$, $\Delta H^\circ_{\mathrm{rxn}}=-114.2\ \mathrm{kJ}$

(5) $\mathrm{N_2O_5(s)\rightarrow N_2O_5(g)}$, $\Delta H^\circ_{\mathrm{subl}}=54.1\ \mathrm{kJ}$

Calculate the heat of reaction for:

$\mathrm{N_2O_3(g)+N_2O_5(s)\rightarrow 2N_2O_4(g)}$