CH302 exam 4

# CH302 exam 4 - Version 191 – Exam 4 – rowland –(53210...

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 191 – Exam 4 – rowland – (53210) 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 When the reaction 3 NO(g) → N 2 O(g) + NO 2 (g) is proceeding under conditions such that 0.015 mol/L of N 2 O is being formed each second, the rate of the overall reaction is ? and the rate of change for NO is ? . 1. 0.015 M · s- 1 ;- 0.005 M · s- 1 2. 0.030 M · s- 1 ;- 0.005 M · s- 1 3. 0.015 M · s- 1 ; +0.045 M · s- 1 4. none of the other answers is correct 5. 0.015 M · s- 1 ;- 0.045 M · s- 1 correct Explanation: Notice that three moles of NO are required to make one mole of N 2 O in this reaction, so the rate of disappearance of NO (which has a negative sign) is three times the rate of appearance of N 2 O. 002 10.0 points Express the rate of the following reaction in terms of the [SF 6 ]. 2 CH 2 S + 12 F 2-→ C 2 F 4 + 4 HF + 2 SF 6 1. rate = 2Δ[SF 6 ] Δ t 2. rate = Δ[SF 6 ] Δ t 3. rate = Δ[SF 6 ] 2Δ t correct 4. rate =- 2Δ[SF 6 ] Δ t 5. rate =- Δ[SF 6 ] 2Δ t Explanation: rate =- [CH 2 S] 2Δ t =- [F 2 ] 12Δ t = [C 2 F 4 ] Δ t = [HF] 4Δ t = [SF 6 ] 2Δ t 003 10.0 points What is the molar solubility of CuBr in 0.5 M NaBr? The K sp is 4 . 2 × 10- 8 . 1. 4 . 20 × 10- 7 2. 8 . 40 × 10- 8 correct 3. 4 . 20 × 10- 8 4. 2 . 05 × 10- 4 5. 3 . 48 × 10- 3 Explanation: 004 10.0 points Consider the addition of 0.130 moles of solid NaOH to 1.0 liter of 0.230 M HCl. What will be the pH of the resulting solution? As- sume no volume change due to the addition of NaOH. 1. pH = 0.50 2. pH = 0.75 3. pH = 1.00 correct 4. pH = 1.50 5. pH = 2.00 Explanation: 005 10.0 points A buffer solution contains 0.0200 M acetic acid and 0.0200 M sodium acetate. What is the pH after 2.0 millimoles of HCl are added to 1.00 L of this buffer? p K a = 4.75 for acetic Version 191 – Exam 4 – rowland – (53210) 2 acid. 1. 4.66 correct 2. 4.80 3. 4.70 4. 4.84 5. 4.75 Explanation: 006 10.0 points The curve for the titration of formic acid (HCOOH) with NaOH(aq) base is given be- low. 2 4 6 8 10 12 14 20 40 60 80 100 120 140 Volume of base (mL) pH Estimate the p K a of formic acid. C a = . 66, C b = 0 . 6204, and the volume of HCOOH is 100 mL. 1. 47 2. None of these 3. 8 . 37 4. 94 5. 3 . 7 correct Explanation: K a = 1 . 8 × 10- 4 C a = 0 . 66 C b = 0 . 6204 V HCOOH = 100 mL 2 4 6 8 10 12 14 20 40 60 80 100 120 140 Volume of base (mL) pH (94,8 . 37) (47,3 . 7) The equivalence point of this titration is when the curve is at an inflection point (nearly vertical); i.e. , at a volume of 94 mL . The pH at the equivalence point of this titration is 8 . 37 pH ....
View Full Document

{[ snackBarMessage ]}

### Page1 / 8

CH302 exam 4 - Version 191 – Exam 4 – rowland –(53210...

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

View Full Document
Ask a homework question - tutors are online