Organic Chemistry Answers

1, Explain the role of a salt bridge in a voltaic cell

2, Assign oxidation numbers to the following compounds:

a. KClO3 b. NO3 c. CH3 CHO

3, Balance the following half-reaction in an acidic solution:

Cr₂ O₇^2- → Cr³⁺

How is an oxidizing agent different than an oxidation reaction? 

In order for a reaction to happen spontaneously, which reaction (oxidation or reduction) needs to be higher on the redox table? Why?

What is the difference between an oxidation number and a valence number?

I only need the answers please, I want to check if I am correct. Thanks in advance

Which type or types of bonding exist within the complex ion [Cr(H₂O)₆]³⁺?

A. Dative covalent only

B. Dative covalent and covalent only

C. Dative covalent and ionic only

D. Dative covalent, covalent and ionic

In which of these complex ions does the transition metal have an oxidation number of+3?

A. [Ag(CN)2]-

B. [CuCl4]2-

C.[Fe(CN)6]3-

D. [Ni(EDTA)]2-

Which best explains why [Cu(NH3)2]+ ions are colourless?

A. all complex ions having a metal ion with a +1 charge are colourless

B. no electronic transitions can take place between d orbitals

C. the d orbitals cannot split in energy

D. there are no electrons in the d-subshell

Excess zinc powder is added to an acidified solution of the compound NH4VO3 .

Explain the sequence of reactions that takes place; include a description of what you would see and the relevant ionic equations with their calculated Ecell values.

Describe the reactions of separate portions of aqueous copper(II) ions with aqueous sodium hydroxide solution, with excess aqueous ammonia solution and with concentrated hydrochloric acid. In your answer you should link observations with equations which include the formulae of any copper-containing complex ions. Include state symbols.

Data Table Molarity of Na2S2O3

0.125 M Initial Buret Reading (Na2S2O3) 1.50 mL

Final Buret Reading (Na2S2O3) 14.35 mL 

3. Use the average volume and molarity of Na2S2O3 to determine the molarity of the diluted bleach.

Procedure

1. Use a pipet bulb and a 5-mL transfer pipet to measure EXACTLY 5.00 mL of a commercial bleach solution into a 100-mL volumetric flask.
2. Dilute to the mark with distilled water, stopper, and mix well.
3. Weigh out approximately 2 g solid KI. This is a large excess over that which is needed.
4. Pipet EXACTLY 25.0 mL of the dilute bleach into an Erlenmeyer flask.
5. Add the solid KI and about 25 mL of distilled water. Swirl to dissolve the KI.
6. Working in a fume hood, add approximately 2 mL of 3 M HCl while stirring the solution. The solution should be dark yellow to red-brown from the presence of the I3- complex ions.
7. Fill the buret with 0.100 M sodium thiosulfate solution (this may have already been done for you). Record the initial buret reading and the solution molarity in the Data table.
8. Titrate with the standard 0.100 M sodium thiosulfate solution until the iodine color fades to light yellow.
9. Add one dropperful of starch solution. The blue color of the starch-iodine complex should appear.
10. Continue the titration until one drop of Na2S2O3 solution causes the blue color to disappear. Record the final buret reading in the Data Table.

Question--> How would each of the following laboratory mistake affect the calculated value of the percent NaClO in the commercial bleach (too high, too low, no change)? Explain. a. In step 6, some of the iodine that formed sublimed from the solution. 

Data Table Molarity of Na2S2O3 0.125 M Initial Buret Reading (Na2S2O3) 1.50 mL Final Buret Reading (Na2S2O3) 14.35 mL 

 Calculate the average molarity of commercial bleach before it was diluted.