Practice term test #1

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Term Test #1

Time for writing: 90 minutes

Weight: 15% Total Marks: 48

Name: __________________
ID No.___________________

Read each question carefully. Show all work. No partial credit can be given if work is not completely shown.

1. [6] Supply the missing name or formula:

tin(IV) sulfate

calcium hypochlorite

iron (II) sulfide

Al₂O₃

 KMnO₄

NH₄HSO₄

2. [9] Write the balanced reaction for each of the following reactions. For those reactions that occur in solution, write down a net ionic reaction, if one exists. For any redox reaction, also include the oxidation and reduction reactions. If no reaction occurs write NO REACTION. Classify each reaction as REDOX, METATHESIS or DECOMPOSITION WITHOUT REDOX. Show the phases for all of the reactants and products.

i) A dilute solution of aqueous ammonia was added to an aqueous solution of copper (II) sulfate.

ii) Hydrogen chloride gas is bubbled through an aqueous solution of sodium carbonate.

iii) Solid gallium (III) sulfite is strongly heated in a vacuum.

3. [4] Give the formal oxidation state for the underlined atom in each of the following chemical species:

i) I₂O₄

ii) Na₃VO₄

iii) KO₂

iv) CoF₆^3-

4. [4] Calculate the number of electrons in 1.00 mL of water at 298 K.

5. [5] Lead carbonate, 24.3 g, was combined with 0.350 mol of HCl in sufficient water to bring the total volume to 0.750 L.

a) Give the balanced net ionic equation for the reaction that occurs.

b) Find the concentrations of the ions at the completion of the reaction.

6. [6] Traumatic acid is composed of carbon, hydrogen and oxygen, and has a molecular weight of 198.26 g/mol. The combustion of 3.080 mg of traumatic acid produced 7.519 mg of carbon dioxide and 2.520 mg of water. Determine the molecular formula for traumatic acid.

7. [8] Fill in each blank with the appropriate answer.

i) nitric acid is a/an _____________ (oxidizing/reducing) acid.

ii) the highest oxidation state that phosphorus can achieve is ______________

iii) The number of moles of oxygen atoms in 0.0083 mol of uranyl nitrate hydrate UO₂(NO₃)₂. 6H₂O _______________

iv) Most main group metals lose electrons in order to________________________________

v) Describe the following ionic compounds as water soluble or water insoluble:

a) scandium chloride ____________

b) cesium carbonate _____________

c) Pb(OH)₂ ______________

d) NH₄ClO₄ _____________

8. [6] A 0.336 g sample of impure NaClO₂ was treated with 25.00 mL of 0.113 M Ti⁴⁺ solution. The excess Ti⁴⁺ was back-titrated with 16.87 mL of 0.0183 M Mn²⁺ solution.

The relevant unbalanced reactions are:

ClO₂^- + Ti⁴⁺ + H2O --> Ti³⁺ + ClO₃^- + H⁺

Mn²⁺ + Ti⁴⁺ + H₂O --> MnO₂ + Ti³⁺ + H⁺

a) Balance the equations for the two reactions.

b) Find the number of moles of NaClO₂.

c) Calculate the mass percent of NaClO₂ ,in the original impure sample.

Bonus question: [2] For use in semiconductor devices, silicon crystals are prepared in which only one atom out of every billion is an impurity. If such a crystal weighs one mg, how many foreign atoms does it contain?