CHEM 1500 Study Guide - Final Guide: Hydrogen Peroxide, Chemical Formula, Ionic Compound

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15 Dec 2016

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Actual yield the amount of product(s) actually obtained. Percentage yield = (cid:3047) (cid:3032)(cid:3032)(cid:3047)(cid:3030) (cid:3032)(cid:3031) (cid:883)(cid:882)(cid:882)% (cid:3030)(cid:3047)(cid:3048) (cid:3032)(cid:3031) In most cases, actual yield is less than theoretical yield (and thus percentage yield <100%) because product(s) are formed over several steps. A substance that is produced in one step and consumed in another step. Reversible reactions involve the formation of products (forward reaction) that, in turn, react together to give the reactants back (reverse reaction) Are carried out one after another in a sequence. Have the yield of a final product dependent on the outcome of each of the reactions in the sequence. Simultaneous reactions involve substances reacting independently of one another. See slideshow 26 for example (slide 20-32) their yield is a cumulative of product(s) of each independently occurring reaction. Are used in quantitative analysis: e. g. of quantitative reactions include precipitation, neutralization, oxidation-reduction. Deals with determining the amounts of various substances in a sample: e. g. titration.

Related Questions

I need help on number 7!!!

Learning Goal:

To determine equilibrium concentrations from initial conditions.

The reversible reaction

XY(aq)âX(aq)+Y(aq)

has a reaction quotient Qc defined as

Qc=[X][Y][XY]

Because the reaction is reversible, both the forward and reverse reactions will occur simultaneously. The reaction will eventually reach equilibrium, at which point the concentrations do not change, and Qc is equal to a constant known as Kc.

Part C

Based on a Kc value of 0.180 and the data table given, what are the equilibrium concentrations of XY, X, and Y, respectively?

Express the molar concentrations numerically.

This is the description from my organic chemistry lab.

Lab Observations and Data

We obtained 1.17g of cyclohexene oxide (clear liquid) and 3 mL of water into a 50 mL flask with a stir bar. When added a single drop of sulfuric acid, the clear liquid started to change to a very, very light yellow/brownish color. We obtained an ice bath on the side in case our mixture started to boil. After the solution stirred for about 25 minutes, we added sodium hydroxide. We inserted a pH paper and it turned a dark blue, meaning basic. Added another drop of sulfuric acid to make it a little less basic. Added the mixture to a separation funnel, shook it around and ended with separated layers. We separated the layers, thinking the bottom layer was the organic layer, when it was really the aqueous layer. So we ended up mixing the wrong layers back together. After some error, we isolated our new organic layer and added some drying agent. We then put that mixture with the drying agent, NaOH, into the rotovap. Our final product was a white powder and weighed 1.51 grams. We then set up a vacuum filtration while boiling water. We boiled our dried organic layer into the hexane. Added two drops of ethyl acetate to help the boiling process go faster. After vacuum filtering it, it weighed .394 grams. The melting point is 91 to 93 degrees Celsius. Our IR spectra matches the "trans" conformation. So for our TLC plate we observed blue dots to match the trans conformation.

The question is "calculate your percent yield" Which is actual yield/theoretical yield x 100. I just dont understand how I get those numbers.

Here is the lab manual description as well.

Procedure for the Preparation of 1,2-Cyclohexanediol Place a mixture of 1.18 g (0.012 mole) of cyclohexene oxide and 3 mL water into a 50 mL Erlenmeyer flask, equipped with a magnetic stir bar. To this mixture with vigorous stirring add one drop of 6 M sulfuric acid (33% H2SO4) Caution: After a short incubation time, the reaction mixture will become quite warm. This epoxide ring opening reaction is very exothermic. (Why?) If the reaction mixture begins to boil, place the flask in a bath of ice and water. Allow the reaction mixture to stir for the next 15 minutes and let it cool to room temperature. Afterwards, add a small amount of 10% sodium hydroxide drop-wise to neutralize the stirring solution. (No more than 3 or 4 drops of 10% NaOH should be necessary.) Place a drop of the reaction mixture on pH paper to check the pH. Extract the product from the reaction mixture into ethyl acetate or diethyl ether (2 x 15 mL). Dry the combined extracts over sodium sulfate. Decant the solution and remove the solvent to yield the crude product (~1 g). The product can be purified by recrystallization from a small amount (~ 5 mL) of hot toluene or hexanes. Collection of the purified product by suction filtration yields 1,2-cyclohexanediol. The cis isomer has a melting point of 97-101 Â°C whereas the trans isomer melts at 101-103 Â°C. Determine the product(s) or products the reaction. Include a percent yield calculation in your report along with the results of your TLC analysis

CHEM 1500 Study Guide - Final Guide: Hydrogen Peroxide, Chemical Formula, Ionic Compound

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