PERIODIC TABLE, ACTIVITY SERIES, AND OTHER INFORMATION THAT MAY BE USEFUL ON LAST PAGE.
 

1. Good morning! An average cup (250 mL) of coffee contains 125 mg caffeine (C₈H₁₀N₄O₂). What is the molarity of caffeine in coffee? {5)
 

2. Pure ("glacial") acetic acid is a liquid with a density of 1.049 g/mL at 25C.
(a) Calculate the molarity of a solution of acetic acid made by dissolving 10.00 mL of glacial acetic acid at 25C in enough water to make 100.0 mL of solution. {5}
(b) Will the molarity of the acetic acid solution prepared in part (a) increase, decrease, or remain unchanged if the temperature is raised to 60C? {3}

3. (a) List two components (there are many) that contribute to the Internal Energy (E) of a system comprising 50 mL water contained in a beaker. {4}
(b) If the system absorbs 327 kJ heat from the surroundings and does 430 kJ of work on the surroundings, what is E for the process? {4}
(c) Why is H a more useful quantity than q to work with in Chemistry? {4}

4. (a) Complete and balance the following equations in ionic form: (In the case of no reaction, write NR for the right hand side) {2 each}

(i) Al(NO₃)₃ (aq) + ZnBr₂ (aq)

(ii) Al (s) + ZnBr₂ (aq)

(iii) ZnCO₃ + H⁺

(iv) Ba(OH)₂ + HNO₃

(v) Hg₂(NO₃)₂ (aq) + NH₄I (aq)

(vi) H⁺ + ClO₄^-

(b) In the laboratory, how could you distinguish

(i) sodium chloride (table salt) from sodium iodide (a poison)? {2}

(ii) solid barium chloride from solid barium sulfate ? {2} (Lab question)
 

5. The Chemistry Department at Georgetown University has recently ordered a nuclear magnetic resonance (NMR) spectrometer that will operate with radiation of frequency 500 MHz. (It's here now)

(a) What is the wavelength of this radiation? {3}

An einstein is a mole of photons.

(b) How many kJ are contained in an einstein of radiation from the NMR spectrometer? {5}

(c) How many einsteins of this radiation would be needed to raise the temperature of 10.0 g water from 20.0 to 21.5C? {4}
 

6. (a) For any four of the following scientists write a sentence that indicates his contribution to our understanding of the electronic structure of atoms: Einstein, Heisenberg, de Broglie, Pauli, Bohr, Planck. {2 each}

(b) What are the possible values of quantum numbers for a 3d electron? {3}

(c) Which atom has the electron configuration [Ar]3d⁸4s² in its ground state? {3}

(d) Write the electronic configuration for the ground state of arsenic. Does an As atom have any unpaired electrons? {4}

(e) In a potassium atom which kind of electron, 4s or 3d, will experience a greater effective nuclear charge? Why should this be so? {4}
 

7. A sample of CuO weighing 3.50 g was dissolved in 500.0 mL of a solution of HCl (A). The resulting solution (B) was still acidic. A 50.00-mL sample of B was titrated with 0.0850 M NaOH and required 19.50 mL of the alkali for complete neutralization.

Calculate

(a) the molarity of solution B {6}

(b) the molarity of solution A {6}
 

8. Write the following equations in ionic form: {2 each}

(a) 2KMnO₄ + 8H₂SO₄ + 10AgBr ---> 5Br₂ + 2MnSO₄ + 5Ag₂SO4 + K₂SO₄ + 7H2O
 

(b) 8CuSCN + 26HNO₃ + 21H₂O ---> 8CuSO₄ + 8CO₂ + 17NH₄NO₃

9. Which of the following reactions is more exothermic? Why? {3}

(a) CH₃OH (g) + 3O₂ (g) ---> 2CO₂ (g) + 4H₂O (l)

(b) CH₃OH (l) + 3O₂ (g) ---> 2CO₂ (g) + 4H₂O (l)

10. Calculate the enthalpy change for the following reaction {6}

Na₂CO₃ (s) + H₂O (g) + CO₂ (g) ---> 2NaHCO₃ (s)
 

Atomic Weights  C, 12.0; H, 1.0; N, 14.0; O, 16.0; Cu, 63.5
Avogadro's Number 6.02 x 10²³
Planck's Constant 6.63 x 10³⁴ J-s
Speed of light 3.00 x 10⁸ m/s
1 J = 1 kg-m²/s²
1 Hz = 1 s¹
specific heat of water = 4.184 J/g-K
Standard Enthalpies of Formation, H_f (kJ/mol)
CH₃OH (g) -201.2
CO₂ (g) -393.5
H₂O (l) -285.8
H₂O (g) -241.8
Na₂CO₃ (s) -1130.9
NaHCO₃ (s) -947.7