Chap 4 questions

# Chap 4 questions - Which of the following pairs of...

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Which of the following pairs of molecules have the same oxidation number for carbon? a. CO and CO 2 b. CH 4 and CCl 4 c. C 6 H 12 O 6 and C(s) d. H 2 CO and COCl 2 e. Carbon always has an oxidation number of +4 What mass of CuSO 4 .5H 2 O would you need to prepare 250.0 mL of a 0.250 M solution? [MW of CuSO 4 .5H 2 O = 249.5 g/mol] a. 2.5 g b. 15.6 g c. 25.0 g d. 62.5 g e. 15600 g Calculate the concentration of a solution formed when 15.0 mL of 6.00 M HCl are diluted with 25.0 mL of water. a. 0.150 M b. 0.240 M c. 2.25 M d. 3.60 M e. 6.00 M Calculate the molarity of a sodium hydroxide solution if 10.42 mL of this solution are needed to neutralize 25.00 mL of 0.2043 M oxalic acid. H 2 C 2 O 4 (aq) + 2NaOH(aq) --> Na 2 C 2 O 4 (aq) + 2H 2 O(l) a. 1.500 M b. 0.9803 M c. 0.4902 M d. 0.2500 M e. 0.1042 M What is the oxidation number of Cr in potassium dichromate, K 2 Cr 2 O 7 ? a. +2 b. +4 c. +6 d. -4 e. -6 What is the molarity of a solution made by having 90.0 g of acetic acid, CH 3 CO 2 H, in 0.750 L of solution and given the atomic weights: C = 12.01 amu; H = 1.008 amu; O = 16.00 amu? a. 0.076 M b. 1.12 M c. 5.20 M d. 0.90 M e. 2.00 M How many grams of CaO are required for complete reaction with the HCl in 275 mL of a 0.523 M HCl solution? The equation for the reaction is,

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CaO + 2HCl --> CaCl 2 + H 2 O and the atomic weights are Ca = 40.08 amu; O = 16.00 amu. a. 806 g b. 403 g c. 8.06 g d. 4.03 g e. 0.523 g What is the concentration of a NaOH solution made by dissolving 10.0 g NaOH in 50.0 mL of water and adjusting the volume to 250.0 mL? a. 1.00 x 10 -3 M b. 1.00 M c. 5.00 M d. 16.0 M e. 40.0 M For the redox reaction: Ca(s) + 2H 2 O(l) --> Ca 2+ (aq) + 2OH - (aq) + H 2 (g) which of the following statements is true? a. Ca is the oxidizing agent. b. H 2 is reduced. c. Ca is reduced. d. H 2 O is the oxidizing agent. e. H 2 O is oxidized. Sodium thiosulfate is used with silver bromide in film developing. The formula for sodium thiosulfate is Na 2 S 2 O 3 . What is the oxidation number for S, sulfur? a. -2 b. +2 c. -4 d. +4 e. +6 Calculate the molarity of vinegar (acetic acid) solution if you need 34.57 mL vinegar to neutralize (use up) 25.19 mL of 0.1025 M NaOH. CH 3 COOH(aq) + NaOH(aq) --> CH 3 COO - (aq) + Na + (aq) + H 2 O a. 0.07469 M b. 0.07287 M c. 0.03457 M d. 0.02519 M e. 0.1025 M Students were trying to determine the identity of a substance dissolved in water. The solution was odorless and colorless. After they had narrowed the list of possible substances to five compounds they added solutions of Na 2 S, KOH, and HCl to individual samples of the unknown and recorded the results as shown in the table. Possibilities: AgNO 3 ; Na 2 CO 3 ; Na 2 S ; NaCl ; NH 3 Table 1: Observations of Unknown with Test Reagents
with Na 2 S with KOH(aq) with HCl(aq) unknown colorless solution; no precipitate; no bubbling colorless solution; no precipitate; no bubbling colorless solution; no precipitate; no bubbling The dissolved "unknown" substance in the solution is:

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## This note was uploaded on 02/05/2012 for the course CHEM 115 taught by Professor L during the Fall '02 term at Purdue University-West Lafayette.

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Chap 4 questions - Which of the following pairs of...

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