makeupexam1

# makeupexam1 - Version 269 – Make Up Exam 1 – VANDEN...

This preview shows pages 1–3. Sign up to view the full content.

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Version 269 – Make Up Exam 1 – VANDEN BOUT – (53585) 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Consider the reaction 2 C 2 H 2 (g) + 5 O 2 (g) ⇀ ↽ 4 CO 2 (g) + 2 H 2 O(g) and the thermodynamic data Species Δ G f C 2 H 2 50 kcal/mol CO 2- 94 . 2 kcal/mol H 2 O- 54 . 6 kcal/mol Find K p for the reaction. Express your answer as the natural log of K p . 1. ln K p = 600 2. ln K p = 800 3. ln K p = 200 4. ln K p = 400 5. ln K p = 990 correct Explanation: Δ G = (4)(- 94 . 2) + (2)(- 54 . 6)- (2)(50 . 0)- (5)(0 . 0) kcal = (- 586 kcal)(4 . 184 kJ / kcal) =- 2451 . 824 kJ Δ G =- RT ln K p ln K p =- Δ G RT =-- 2451824 J · mol − 1 (8 . 314 J · K − 1 · mol − 1 )(298 K) = 989 . 6 002 10.0 points For gases that do not react chemically with water, the solubility of the gas in water gen- erally (decreases, increases) with an increase in the pressure of the gas and (decreases, in- creases) with increasing temperature. 1. increases; increases 2. decreases; increases 3. increases; decreases correct 4. decreases; decreases Explanation: An increase in pressure means that you have increased the concentration of gas above the solvent surface, thereby increasing the concentration of the gas in the solvent. In- creasing the temperature will decrease the solubility of the gas. 003 10.0 points Everyone should recognize that ? is a strong acid, ? is a weak acid, ? is a strong base, and ? is a salt. 1. HCl; CH 4 ; NaOH; NaCl 2. HCl; CH 3 COOH; NaOH; NaBr correct 3. HCl; H + ; NaOH; NaCl 4. HCl; H 2 SO 4 ; NaOH; NaBr 5. HNO 3 ; CH 3 COOH; NaOH; MgO Explanation: Of the answer choices, hydrochloric acid (HCl), nitric acid (HNO 3 ), and sulfuric acid (H 2 SO 4 ) are strong acids because they dis- sociate completely in water. Acetic acid (CH 3 COOH) is a weak acid due to its par- tial dissociation. Sodium hydroxide (NaOH) and magnesium oxide (MgO) are strong bases, dissociating completely to yield hydroxide (OH − ). Sodium bromide (NaBr) and sodium chloride (NaCl) are salts, compounds com- posed of a cation (metal) other than H + and an anion (non-metal) other than OH − or O 2 − . Version 269 – Make Up Exam 1 – VANDEN BOUT – (53585) 2 004 10.0 points Liquid metallic zinc (Zn) has a vapor pressure of 40 torr at 673 ◦ C and 100 torr at 736 ◦ C. Predict the normal boiling point of zinc. 1. 1452 K 2. 906 K 3. 1183 K correct 4. 1252 K 5. 1076 K Explanation: T 1 = 673 ◦ C + 273 = 946 K P 1 = 40 torr T 2 = 736 ◦ C + 273 = 1009 K P 2 = 100 torr We must first calculate Δ H vap , Zn : ln parenleftbigg P 2 P 1 parenrightbigg = Δ H vap , Zn R parenleftbigg 1 T 1- 1 T 2 parenrightbigg Δ H vap , Zn = R ln parenleftbigg P 2 P 1 parenrightbigg 1 T 1- 1 T 2 = parenleftbigg 8 . 314 J mol · K parenrightbigg ln parenleftbigg 100 torr 40 torr parenrightbigg 1 946 K- 1 1009 K = 1 . 15421 × 10 05 J / mol The normal boiling point is at 760 torr,...
View Full Document

{[ snackBarMessage ]}

### Page1 / 11

makeupexam1 - Version 269 – Make Up Exam 1 – VANDEN...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online