Some sample final exam questions

Note that the final exam is cumulative and will thus cover all the topics in the course, including those from before the midterm.

1. Supply the missing name or formula:

palladium (II) phosphate ____________________________________

strontium nitrate hydrate ____________________________________

_______________________________ N₂O₄

_______________________________ Fe(ClO₄)₃

2. Write a balanced equation for each of the following reactions.

If no reaction occurs, write “no reaction”. Show all phases for the reactants and products.

a) A concentrated solution of aqueous ammonia is added to an aqueous solution of copper (II) sulfate.

b) Solid aluminium metal and liquid bromine are combined under anhydrous (i.e. dry) conditions.

c) Nickel (II) hydroxide is strongly heated.

d) Solid boron oxide is added to water.

e) Solid calcium oxide is added to a concentrated aqueous

solution of perchloric acid.

f) A solid sample of mercury (II) oxide is strongly heated under vacuum.

3. Write a balanced reaction for the preparation of gaseous hydrogen chloride using the reaction of pure anhydrous (no water present) sulfuric acid with another common inorganic compound.

4. Boron trifluoride reacts readily with phosphine (PH₃).

a) Draw the Lewis structures of phosphine and of boron trifluoride.

b) Draw the structure of the product.

c) Is this an acid-base reaction? If yes, identify the acid and the base. If not, explain why.

5. Which compound is a stronger acid, H₂O or H₂S? Explain your answer in one or two clear sentences.

6. a) Arrange the following binary compounds in order of increasing acid strength:

HI, PH₃, H₂Se, CH₄

b) In one clear sentence, explain why HF is a weak acid whereas HCl is a strong acid.

7. Answer the following by filling in each blank with the appropriate answer, or by circling the correct choice, as appropriate.

a) Which is the stronger oxidizing agent, Pb(IV) or Pb(II)? ____________

b) Which element has a larger sixth ionization energy, P or S? ____________

c) The bonding within the compound SbF₅ is primarily ionic / covalent? (Circle one)

d) What is the conjugate base of the hydroxide ion? _______________

e) The electron affinity of groups 2 and 18 is close to zero. Which other group (in the s and p blocks) has an electron affinity which is smaller than would be expected on the basis of the general trends? _____________________

f) Identify the neutral element that is isoelectronic with the cation Po⁴⁺. _______________

g) Consider the compounds: LiCl, MgCl₂, NaCl, CCl_4. Which has the greatest ionic character? ____________________

h) Molecular nitrogen (N₂) and carbon monoxide (CO) are isoelectronic and have virtually identical molecular masses. Which substance has the higher melting point? ________________________

i) ZrBr₄ melts at 382 K and the pure liquid does not conduct electricity. What type of solid (ionic, molecular or network covalent) is ZrBr₄? _________________

j) Which pure liquid substance can form a greater number of intermolecular hydrogen bonds, H₂O or NH₃ ? ____________________

k) Dichloromethane is polar/non-polar. _______________ (Choose one)

l) Consider a gas where the particles have a non-zero volume. If 1.00 mol of this gas were confined to a container, would its pressure differ from that of the same amount of an ideal gas in the same container? Would it be higher / lower / the same ? (Choose one)

m) What type of intermolecular interaction is present in every substance? ______________________

8. Pick the best answers for the following multiple choice questions:

i) Out of the substances NH₄Cl, Cu(NO₃)₂, K₂CO₃ and NaF, which would give a basic solution when dissolved in water?

a) NH₄Cl and Cu(NO₃)₂

b) K₂CO₃ and NH₄Cl

c) NaF only

d) K₂CO₃ and NaF

e) NH₄Cl only

ii) Of the following, which is the strongest acid?

a) HIO

b) HIO₂

c) HIO₄

d) HIO₃

e) The acid strength of all of these is nearly the same.

iii) The more electronegative X is, the ____________ polar will be the H-X bond and the ______________ easily the H-X bond will be broken, making HX ________________ acidic.

a) more, less, weakly

b) more, more, weakly

c) more, more, strongly

d) more, less, strongly

e) less, less, strongly

iv) A new element is discovered. It has two isotopes. The relative abundances of the isotopes and their masses are 18 % isotope 1, mass 350.0 g/mol and isotope 2, mass 352.0 g/mol. What is the atomic mass of the element?

a) 351.6

b) 351.0

c) 350.4

d) 352.0

e) 350.0

v) The oxidation state of vanadium in VO²⁺ is :

a) -2

b) +2

c) +1

d) -4

e) +4

vi) The oxidation state of boron in B₅H₉ is:

a) +3

b) 0

c) -1/2

d) + 9/5

e) - 9/5

9. Noble gas compounds such as XeF₂ are well known. Consider the compound XeBr₂. Would you expect that it could be prepared? How would its stability compare with that of XeF₂?

b) Write a balanced molecular equation and a net ionic equation where

appropriate for each of the following reactions. If no reaction occurs, write

“no reaction”. Show all phases for the reactants and products.

10. Liquid pentaboron nonahydride (B₅H₉) reacts with water to form solid boric acid (H₃BO₃) and molecular hydrogen gas.

a) Write a balanced equation for the reaction.

b) Classify the reaction as either redox or metathesis.

c) If 3.00 g of liquid water were added to 2.50 g of B₅H₉ (l), how many litres of molecular hydrogen gas, measured at 750.0 mmHg and 20.0^oC, would be produced? Assume the reaction goes 100 % to completion.

11. Explain the following observations in one or two sentences:

a) aluminum trichloride (AlCl₃) reacts vigorously with ammonia

b) carbon tetrachloride is completely non-polar

c) titanium tetrachloride is a liquid at room temperature, even though the electronegativity difference between the elements is large

d) dinitrogen has a lower boiling point than carbon monoxide

e) pure water is a poor conductor of electricity

f) oil and water do not mix

g) graphite is a good lubricant whereas diamond is not