[COmtbiker12]

Alright so at school we had to get into groups and create an experiment somewhere under the topic of 'food'. So my group decided to test the carbon dioxide produced from the fermentation of different sugars (dissolved in water). (Originally we wanted to test enthalpy and such related to the alcohol that was made, but that didn't fly too well with the teachers ) Anyways... so now I'm writing my lab report and am trying to do error analysis and find out the percent error from the our experimental/theoretical yield was. However I'm not sure how I would calculate in some of the variables to come up with some of the results.

Basically thus far we have these equations that we found, but so far the only error analysis I've been able to figure out is with the 'simplified' equation which doesn't allow any further input besides the varying amounts of sugar. Anybody know how I would set it up so that I can include varying amounts of yeast as well? I'm obviously a beginner at chemistry so I'm not too sure what all to put for it...ink:

Thanks.

Full Respiration Equation: C6H12H6 + 2 ATP + 2 NAD+ + 2 Pi + 4 ADP → 2 pyruvate + 2 ADP + 2 NADH + 4 ATP + 2 H2O + 4 H+

Simplified Respiration Equation (ignoring recycled components and ATP production): C6H12O6 + 6O2 → 6CO2 + 6H2O

 

[robdamanii]

The first equation you've got there is loosely the steps of glycolysis (no enzymes or anything), the second is a very simplified version of the cytochrome chain. Are you doing anaerobic respiration? In the case of anaerobic respiration, you're looking at:

Glucose goes through the glycolysis pathway to give you this:

Pyruvate yields Acataldehyde and C02 with the assistance of Pyruvate decarboxalase, then alcohol dehydrogenase uses an NADH (oxidizes to NAD+) and produces ethanol.

If you're talking fermentation, I'd think it would be all anaerobic. Fermentation, at least by biological definition, is anaerobic. The sugar amounts and yeast amounts being constant, the only variable is the amount of CO2 produced by each kind of sugar.

 

[elRey]

chem suxx

 

[COmtbiker12]

The first equation you've got there is loosely the steps of glycolysis (no enzymes or anything), the second is a very simplified version of the cytochrome chain. Are you doing anaerobic respiration? In the case of anaerobic respiration, you're looking at:

Glucose goes through the glycolysis pathway to give you this:

Pyruvate yields Acataldehyde and C02 with the assistance of Pyruvate decarboxalase, then alcohol dehydrogenase uses an NADH (oxidizes to NAD+) and produces ethanol.

If you're talking fermentation, I'd think it would be all anaerobic. Fermentation, at least by biological definition, is anaerobic. The sugar amounts and yeast amounts being constant, the only variable is the amount of CO2 produced by each kind of sugar.

Rob, yeah we called it 'aerobic respiration lab'. Well that's good that if it's constant the only thing changing should be the amount of CO2 produced. I think I'll just stick to the simplified version for calculating my percent error analysis, lol, I just realized that I need to do it for each test and trial for each individual sugar. Pain in the ass... what I originally pictured as a 5page lab is going to end up being at least 10 I think...

 

[-dustin]

oh **** i hated that stuff.

 

[robdamanii]

Rob, yeah we called it 'aerobic respiration lab'. Well that's good that if it's constant the only thing changing should be the amount of CO2 produced. I think I'll just stick to the simplified version for calculating my percent error analysis, lol, I just realized that I need to do it for each test and trial for each individual sugar. Pain in the ass... what I originally pictured as a 5page lab is going to end up being at least 10 I think...

Hrm. If you used the same amount of yeast each exeriment, then the yeast is the limiting reagent, which means you could load up sugar and it wouldn't matter. CO2 should be the only variable product, at least in theory.

Damn, been a long time since I've done the numbers of any kind of chemistry. Now we only have to know all the glycolysis reaction, all the citric acid cycle, and all the cytochrome chain. Fun.....

I think you're on the right track though, as far as I can remember.

 

[COmtbiker12]

Hrm. If you used the same amount of yeast each exeriment, then the yeast is the limiting reagent, which means you could load up sugar and it wouldn't matter. CO2 should be the only variable product, at least in theory.

Damn, been a long time since I've done the numbers of any kind of chemistry. Now we only have to know all the glycolysis reaction, all the citric acid cycle, and all the cytochrome chain. Fun.....

I think you're on the right track though, as far as I can remember.

I think you remember more than I've learned so far.

That definitely makes sense with yeast being the limiting reactant though. I just wish I knew more of the fundamentals of setting up the mathematical equations to coincide with the other equations, at least the more complicated ones like these (we haven't done any this demanding yet in class)

 

[robdamanii]

I think you remember more than I've learned so far.

That definitely makes sense with yeast being the limiting reactant though. I just wish I knew more of the fundamentals of setting up the mathematical equations to coincide with the other equations, at least the more complicated ones like these (we haven't done any this demanding yet in class)

Lol. High school chem? I hated chem until I got to college level and had to take about 24 credits of it, both applied and "numbers" chem. Plus, having a prof that blows things up is a LOT of fun and helps you learn.

 

[COmtbiker12]

Lol. High school chem? I hated chem until I got to college level and had to take about 24 credits of it, both applied and "numbers" chem. Plus, having a prof that blows things up is a LOT of fun and helps you learn.

Lol yeah high school chem.

Fortunately I do have a teacher that likes to light things on fire. It is fun, just times like this where I feel limited by my knowledge.

 

[Wumpus]

Fermentation: http://people.howstuffworks.com/winemaking4.htm

You probably should have used a hydrometer to test the sugar level(density) of the starting solution and then again at the final time. I made some wine in chemistry(was a long time ago) and if I remember right the yeast will keep metabolizing the sugar until it is all converted(or the yeast dies due to alcohol content). So really if you only did for a certain length of time, you are measuring whether more yeast will move the reaction along quicker.

By the way, as fermentation cannot increase alcohol content past about
16%, for at that level the yeast dies and ends fermentation. Higher
alcohol levels are archived through"distillation" (that is a lower alcohol
beverage is heated. Alcohol, evaporating first, is collected and the vapor
re-condensed).

http://www.faqs.org/faqs/drink/wine-faq/part2/

 

[robdamanii]

Fermentation: http://people.howstuffworks.com/winemaking4.htm

You probably should have used a hydrometer to test the sugar level(density) of the starting solution and then again at the final time. I made some wine in chemistry(was a long time ago) and if I remember right the yeast will keep metabolizing the sugar until it is all converted(or the yeast dies due to alcohol content). So really if you only did for a certain length of time, you are measuring whether more yeast will move the reaction along quicker.

Wouldn't it be if he used the same amount of yeast but different sugar substrates, he'd be measuring the yield of CO2 due to different sugar substrates? Assuming the amount of yeast and the time were constant?

 

[Wumpus]

Wouldn't it be if he used the same amount of yeast but different sugar substrates, he'd be measuring the yield of CO2 due to different sugar substrates? Assuming the amount of yeast and the time were constant?

Since the sugar is being converted to CO2, it would be good to know how much sugar was consumed.

Curious: How was the CO2 being measured?

 

[robdamanii]

Since the sugar is being converted to CO2, it would be good to know how much sugar was consumed.

Curious: How was the CO2 being measured?

Good point. The reaction would have to progress to completion until all the sugar was gone then. Sugar would be the limiting reagent. So same amount of sugar would give you different volumes of CO2 gas.

Correct?

 

[Wumpus]

For some reason I read that they were varying yeast concentration. Still would be useful to know the concentrations before and after to compare numbers.

 

[Wumpus]

Good point. The reaction would have to progress to completion until all the sugar was gone then. Sugar would be the limiting reagent. So same amount of sugar would give you different volumes of CO2 gas.

Correct?

As long as a lethal alcohol content isn't reached before all the sugar is converted. That is why some wines are sweet and some are dry.



*Heat can also kill the yeast.

 

[COmtbiker12]

We had it setup fairly simple, we had the yeast/sugar/water in some erlenmeyer flasks with stoppers in them and had tubes attached to them. We had the tubes then leading to larger erlenmeyer flasks that were upside down and submerged and we measured the displacement of the water from those flasks.

We weren't varying yeast concentration and had some basic baking yeast that we got at a grocery store. We used 1g of dextrose, fructose, sucrose, Splenda, and corn syrup as the different sugars, 150mL of water, and then 7g of yeast.

 

[BurlyShirley]

I didnt read the question but if you mix drano and tinfoil cool stuff happens.

 

[JRB]

Also, feeding alka-seltzer makes their guts blow up.

 

[BurlyShirley]

Also, feeding alka-seltzer makes their guts blow up.

Alka seltzer has guts?

 

[Westy]

Alka seltzer has guts?

Probably not, I tried feeding mine and it just sits there not eating anything.

 

[Wumpus]

Simplified Respiration Equation (ignoring recycled components and ATP production): C6H12O6 + 6O2 → 6CO2 + 6H2O

btw - I think you have to use this equation since it is not complete respiration --

C6H12O6 => 2(CH3CH2OH) + 2(CO2)

 

[robdamanii]

btw - I think you have to use this equation since it is not complete respiration --

C6H12O6 => CH3CH2OH) + 2(CO2)

Fermentation, yeah.

 

[JRB]

Crap - alka seltzer to sea gulls. I just assumed you all knew.