1997 - U.S. National Chemistry Olympiad: 1997 National Test...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
U.S. National Chemistry Olympiad: 1997 National Test Go to the answers 1. The formula of sodium tungstate is Na 2 WO 4 and that of lead phosphate is Pb 3 (PO 4 ) 2 . What is the formula for lead tungstate? (A) PbWO 4 (B) Pb 2 (WO 4 ) 3 (C) Pb 3 (WO 4 ) 2 (D) Pb 3 (WO 4 ) 4 2. A metal from period 4 is added to water and a vigorous reaction takes place with the evolution of a gas. Which statements are correct? 1. Oxygen is evolved. 2. Hydrogen is evolved. 3. The resulting solution is acidic. 4. The resulting solution is basic. (A) 1 and 3 only (B) 2 and 3 only (C) 2 and 4 only (D) 1 and 4 only 3. 30.mL of 0.10 Ba(OH) 2 (aq) is added to 30. mL of 0.10 M H 2 SO 4 (aq) and the solution is stirred quickly. The rise in temperature, T 1 , is measured. The experiments is repeated using 90.mL of each solution and the rise in temperature, T 1 , is measured. What is the relationship between T 1 and T 2 ? (A) T 2 is equal to T 1 (B) T 2 is three times as large as T 1 (C) T 2 is six times as large as T 1 (D) T 2 is one-third as large as T 1 4. An aqueous solution is 0.1 M in each of these ions. 1. Cu 2+ 2. Hg 2+ 3. Pb 2+ Which ion(s) will precipitate if 0.1 M HCI is added?
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
(A) 2 only (B) 3 only (C) 2 and 3 only (D) 1,2, and 3 5. The age of a wooden artifact was determined by carbon-14 dating. Three different measurements gave values of 6925, 4815, and 5485 years. Which is the best value to report for the age of this artifact? (A) 5700 years (B) 5740 years (C) 5741 years (D) 6000 years 6. What is the molality, m, of methanol in a solution prepared by dissolving 160 g of methanol, CH 3 OH, in 200.0 g of water? (A) 1.0 m (B) 5.0 m (C) 10.0 m (D) 25.0 m 7. What is the coefficient for oxygen when this equation is balanced? Sb 2 S 3 (s) + O 2 (g) ---> Sb 2 O 3 (s) + SO 2 (g) (A) 9 (B) 7 (C) 5 (D) 4 8. Flourine reacts with uranium hexaflouride, UF 6 , as represented by this equation. U(s) + 3F 2 (g) ---> UF 6 (g) How many flourine molecules are required to produce 2.0 mg of uranium hexaflouride, UF 6 , from an excess of uranium? The molar mass of UF 6 is 352.0 g mol¯ 1 (A) 3.4 x 10 18 (B) 1.0 x 10 19 (C) 2.0 x 10 19 (D) 3.4 x 10 21 9. Magnesium hydroxide, Mg(OH) 2 , is the white milky substance in milk of magnesia. What mass of Mg(OH) 2 is formed when 15mL of 0.18 M NaOH are combined with 12mL of 0.14 M MgCl 2 ? The molar mass of Mg(OH) 2 is 58.3 g mol¯ 1
Background image of page 2
(A) 0.079 g (B) 0.097 g (C) 0.16 g (D) 0.31 g 10. What is the concentration of H + in a solution that is prepared by mixing 50.0 mL of 0.50 M HCl with 200.0 mL of 0.25 M HCl? (A) 0.30 M (B) 0.35 M (C) 0.40 M (D) 0.45 M 11. Which concentrations can be calculated if the mole fraction and density of an aqueous solution of HCl are known? 1. molality
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 15

1997 - U.S. National Chemistry Olympiad: 1997 National Test...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online