Chemistry Preliminary Exam-James Ruse

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Student Number

Mark / 39

Chemistry
Preliminary Course Final Examination • 2006

General Instructions • • • • • • • Reading time – 5 minutes Working time – 45 minutes Write using black or blue pen Draw diagrams using pencil Board-approved calculators may be used A Data Sheet and a Periodic Table are provided Write your Student Number at the top of this page

Total Marks – 39 Part A – 10 marks • Attempt Questions 1 – 10 • Allow about 10 minutes for this part

Part B – 29 marks • Attempt Questions 11 – 19 • Allow about 35 minutes for this part

Part A – 10 marks Attempt Questions 1 – 10 Allow about 10 minutes for this part

Answer Box for Questions 1 – 10
1 2 3 4 5 6 7 8 9 10 A A A A A A A A A A B B B B B B B B B B C C C C C C C C C C D D D D D D D D D D

JRAHS Chem 11 – Final Examination – 2006

Page 2 of 11

► Mark your answers for Questions 1 – 10 in the Answer Box on page 2.

1

The law of combining volumes states that the ratio of gases involved in a chemical reaction can be expressed in simple whole number ratios. Identify who proposed this law? (A) (B) (C) (D) Dalton Gay–Lussac Avogadro Mendeleev

2

Which statement is correct for NO2 gas? (A) (B) (C) (D) One molecule has a mass of 46 g. One molecule occupies a volume of 24.79 L at 0°C and 100 kPa. One mole contains 6.02 × 10 23 atoms of oxygen. One mole contains 6.02 × 10 23 molecules.

3

The extraction of a metal from its ore involves a series of steps as shown… mine ore concentrate ore extract metal via smelting purify the metal

Which chemical equation represents a reaction that would be appropriate for the metal extraction step for copper from its ore? (A) (B) (C) (D) FeO (s) + SiO2 (s) → FeSiO3 (l) 2CuFeS2 (s) + 5O2 (g) → 2Cu (l) + 2FeO (s) + 4SO2 (g) Cu → Cu2+ + 2e– CuO (s) + Mg (s) → MgO (s) + Cu (s)

4

Which of these processes is endothermic? (A) (B) (C) (D) decomposition of silver chloride to silver and chlorine burning methane condensing steam adding sodium metal to water

JRAHS Chem 11 – Final Examination – 2006

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5

Which graph represents the change in potential energy for the reaction… 2NO2 (g) → N2 (g) + 2 O2 (g) ΔH = +33.7 kJ mol–1

(A) (B) (C) (D) 6

Graph A Graph B Graph C Graph D

A compound contains potassium, sulfur and oxygen only. A sample of the compound is found to contain 41.1 mg of potassium, 33.8 mg of sulfur and 25.2 mg of oxygen. Which of the following represents the empirical formula of the compound? (A) (B) (C) (D) K2SO4 K2SO3 K2S2O3 K2SO2

7

In a calorimeter, a 1.000 g sample of magnesium is burned to form MgO, and in so doing, releases 6.075 kJ of energy. What is the heat of combustion, in kJ, of one mole of magnesium? (A) (B) (C) (D) 6.075 72.90 147.7 3.65 × 1025

JRAHS Chem 11 – Final Examination – 2006

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8

10 mL of hydrogen fluoride gas reacts with 5 mL of dinitrogen difluoride gas to form 10 mL of a gas. All gas volumes are measured at the same temperature and pressure. Which of the following is the most likely equation for the reaction? (A) (B) (C) (D) HF (g) + N2F2 (g) → N2HF3 (g) 2HF (g) + N2F2 (g) → N2H2F4 (g) 2HF (g) + N2F2 (g) → 2NHF2 (g) HF (g) + 2N2F2 (g) → N4HF5 (g)

9

The table shows the solubility of salts in water at 25°C.
ANION All All Nitrate, NO3– Acetate/ethanoate CH3COO – Chloride, Cl – Bromide, Br – Iodide, I – Sulfate, SO42– Group I metals Ammonium, NH4+ All All except Ag+ Ag+, Pb2+, Hg22+, Cu+ All others Ca2+, Sr 2+, Ba2+, Pb2+, Ag+, Hg22+ All others Sulfide, S 2–

CATION

COMPOUND soluble soluble soluble soluble insoluble soluble insoluble soluble soluble insoluble soluble insoluble soluble insoluble

Group I and II metals, NH4+ All others

Hydroxide, OH



Group I metals, NH4+, Sr 2+, Ba2+ All others

Carbonate, CO32– Phosphate, PO43– Sulfite, SO32–

Group I metals, NH4+ All others

A student mixed several salt solutions as described in the table. Mixture number 1 2 3 Salt solutions...
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