jimmystewart
Well-Known Member
Hi, all. I've been a long time (mostly) lurker here on the forums and I've learned a whole bunch from reading countless threads. I've always wanted to give something back, and I think I have a worthwhile contribution to offer. I brewed a batch of beer yesterday and decided to conduct a little experiment.
Since I don't post frequently most of you don't know me well. As a scientist I firmly believe we should all question where our information comes from, so I offer my credentials: I've been brewing for almost 5 years and I've probably done a little more than 500 gallons of beer, wine, and cider. I'm a non-traditional college student aiming for a bachelors' degree in Chemical Engineering and I've managed straight A's in Intro Chem (lab & lecture), Chem I (lab & lecture), as well as the Calculus series (and Differential Equations!). I don't share this to brag, but hopefully to lend credibility to what you'll read below.
Oh, and I welcome any comments and/or criticism of my procedure and/or results. I'd love to collect feedback and maybe get some better equipment and more supplies and do something more in depth in the future, but I have no idea when I'd have the time and resources to do this again. If anyone would like to replicate the experiment, please post about it here!
I'll try to check back on this periodically and answer any questions that come up.
Without further ado:
Specific Heat of Wort (A Scientific Approach)
Abstract:
This experiment makes use of the law of conservation of energy, also called the first law of thermodynamics, which states that the total energy (in this case in the form of heat) of an isolated system is constant. When mixing hot wort and cold deionized water, the heat lost by the wort matches the heat gained by the deionized water. Using the known specific heat of deionized water along with the masses and temperatures of the individual samples, the specific heat of the wort can be calculated.
Introduction:
This experiment was performed out of curiosity arising from my inability to conveniently locate a consistent, reliable answer to the question What is the specific heat of wort? in the vast expanse of the internet. This question arose from a synthesis of two of my greatest interests (science and brewing) and specifically came up during a conversation with my chemistry professor around the time of a final exam which included thermochemistry, enthalpy, and calorimetry. A lighthearted challenge was proposed, and my immediate response was: Why not?
Hypothesis:
Before beginning the experiment (based on little more than a hunch) it was anticipated that the specific heat of wort was unlikely to vary more than 3% to 5% from the specific heat of deionized water. Because of the additional density expected from the sugars present in the malt extract used to create the wort, it was anticipated that the specific heat of wort would be higher than that of deionized water. The specific heat of deionized water is 4.18 J/g*C, so it was anticipated that the specific heat of wort would fall somewhere between 4.30 J/g*C and 4.39 J/g*C.
Resources:
The formula q=mc(deltaT) where q=heat transferred in Joules, m=mass in grams, c=specific heat in J/g*C, and deltaT=change in temperature. The specific heat (c) for deionized water is 4.18 J/g*C.
Procedure:
(Preliminary) A concentrated wort was made. In a kettle, one pound of specialty grains was steeped in two gallons of store brand bottled purified water until boiling temperature was reached, then the specialty grains were removed, drained into the kettle, and discarded. Six pounds of dry malt extract was added to the remaining water, which was heated to boiling temperature. This wort was boiled for one hour during which two ounces of hops were added. After water loss to the specialty grains and evaporation during the boil, the volume of this concentrated wort was 1.73 gallons. Samples were taken from this concentrated wort for specific heat testing and one sample was set aside to cool to test specific gravity. The remaining concentrated wort was diluted with store brand purified water to a total volume of 5 gallons. Samples were taken from this diluted wort and reheated for specific heat testing and one sample was set aside to cool to test specific gravity.
(Data collection) When measuring masses, record data accurate to hundredths of a gram. When measuring temperatures, record data accurate to tenths of a degree. Measure and record mass and temperature of an approximately 50 gram sample of chilled deionized water. Measure and record mass and temperature of an approximately 50 gram sample of wort. Combine the two samples in a foam cup calorimeter, then measure and record the temperature of the mixture at equilibrium. Repeat this procedure for a total of three trials for concentrated wort, then repeat for a total of three trials for diluted wort. Cool a sample each of concentrated and diluted wort to 60*F to measure and record specific gravity.
Data:
Specific Heat of Wort (A Scientific Approach)
q=mc(deltaT)
all masses in grams, all temperatures in degrees Celsius
specific heat in J/g*C (specific heat of deionized water = 4.18)
method of calculating was:
m(wort)*c(wort)*[Ti(wort)-Tf] = m(water)*4.18*[Tf-Ti(water)]
{solve for c(wort)}
*(I used underscores to try to preserve the table format here, since it seems the forum software doesn't like me pasting in something copied from a spreadsheet.)
Concentrated Wort -
________mass di___temp di___mass___temp___temp______specific heat
________water_____water____wort___wort____mixture____of wort
Trial 1___55.12_____8.3______52.73___76.4____39.9______3.8
Trial 2___59.32_____8.1______52.27___78.0____38.3______3.6
Trial 3___57.02_____8.4______64.56___73.5____41.7______3.9
_______________average of specific heat from all 3 trials:___3.8
concentrated wort specific gravity: 1.190
* Please see comment in notes!
Diluted Wort -
________mass di___temp di___mass___temp___temp______specific heat
________water_____water____wort___wort____mixture____of wort
Trial 1___59.32_____8.4______63.65___78.6____42.3______3.6
Trial 2___64.78_____8.3______53.64___72.3____34.9______3.6
Trial 3___51.34_____8.4______64.35___67.4____39.0______3.6
_______________average of specific heat from all 3 trials:___3.6
diluted wort specific gravity: 1.061
Conclusions:
The results of this experiment were, quite frankly, a surprise. The specific heat of concentrated wort is 9.1% less than the specific heat of deionized water, and the specific heat of diluted wort is 14% less than the specific heat of deionized water. Not only was the difference three times what was anticipated, but the difference was in the opposite direction from what was anticipated. Upon inspecting the results and contemplating the cause of the difference in specific heat, a possible explanation would be that the sugars and other compounds present in the malt extract act as very good conductors of heat. If this were the case, then one might expect the specific heat of concentrated wort to be lower than the specific heat of diluted wort, yet this is contrary to what was found. Granted, the difference between the specific heat of concentrated and diluted wort is only about 5%, but it is measurable difference.
Notes:
In reference to the concentrated wort specific gravity listed on the data page, when this measurement was attempted it was quite literally off the scale of the hydrometer used. By inspecting the scale of the hydrometer and extrapolating the scale beyond the markings provided, the reasonable estimate of 1.190 was deduced. I felt it relevant to include the specific gravities because this is a measurement frequently used by brewers and would make for a convenient reference point when comparing the concentrated wort to the diluted wort.
Lastly, I do want to acknowledge that the type of specialty grains used as well as the type of dry malt extract and variety of hops used were omitted intentionally. The reason for omission was to keep this experiment and any discussion of this experiment focused strictly on the difference between the specific heat of wort and specific heat of distilled water and to avoid discussing opinions of my recipe. Additionally, I acknowledge that these variables could very well affect the specific heat of the wort, and may come into play in a future experiment, but that was simply beyond the scope of what I had the resources to test at the time of this experiment.
Thanks for taking the time to read this, I really enjoyed putting it together!
Since I don't post frequently most of you don't know me well. As a scientist I firmly believe we should all question where our information comes from, so I offer my credentials: I've been brewing for almost 5 years and I've probably done a little more than 500 gallons of beer, wine, and cider. I'm a non-traditional college student aiming for a bachelors' degree in Chemical Engineering and I've managed straight A's in Intro Chem (lab & lecture), Chem I (lab & lecture), as well as the Calculus series (and Differential Equations!). I don't share this to brag, but hopefully to lend credibility to what you'll read below.
Oh, and I welcome any comments and/or criticism of my procedure and/or results. I'd love to collect feedback and maybe get some better equipment and more supplies and do something more in depth in the future, but I have no idea when I'd have the time and resources to do this again. If anyone would like to replicate the experiment, please post about it here!
I'll try to check back on this periodically and answer any questions that come up.
Without further ado:
Specific Heat of Wort (A Scientific Approach)
Abstract:
This experiment makes use of the law of conservation of energy, also called the first law of thermodynamics, which states that the total energy (in this case in the form of heat) of an isolated system is constant. When mixing hot wort and cold deionized water, the heat lost by the wort matches the heat gained by the deionized water. Using the known specific heat of deionized water along with the masses and temperatures of the individual samples, the specific heat of the wort can be calculated.
Introduction:
This experiment was performed out of curiosity arising from my inability to conveniently locate a consistent, reliable answer to the question What is the specific heat of wort? in the vast expanse of the internet. This question arose from a synthesis of two of my greatest interests (science and brewing) and specifically came up during a conversation with my chemistry professor around the time of a final exam which included thermochemistry, enthalpy, and calorimetry. A lighthearted challenge was proposed, and my immediate response was: Why not?
Hypothesis:
Before beginning the experiment (based on little more than a hunch) it was anticipated that the specific heat of wort was unlikely to vary more than 3% to 5% from the specific heat of deionized water. Because of the additional density expected from the sugars present in the malt extract used to create the wort, it was anticipated that the specific heat of wort would be higher than that of deionized water. The specific heat of deionized water is 4.18 J/g*C, so it was anticipated that the specific heat of wort would fall somewhere between 4.30 J/g*C and 4.39 J/g*C.
Resources:
The formula q=mc(deltaT) where q=heat transferred in Joules, m=mass in grams, c=specific heat in J/g*C, and deltaT=change in temperature. The specific heat (c) for deionized water is 4.18 J/g*C.
Procedure:
(Preliminary) A concentrated wort was made. In a kettle, one pound of specialty grains was steeped in two gallons of store brand bottled purified water until boiling temperature was reached, then the specialty grains were removed, drained into the kettle, and discarded. Six pounds of dry malt extract was added to the remaining water, which was heated to boiling temperature. This wort was boiled for one hour during which two ounces of hops were added. After water loss to the specialty grains and evaporation during the boil, the volume of this concentrated wort was 1.73 gallons. Samples were taken from this concentrated wort for specific heat testing and one sample was set aside to cool to test specific gravity. The remaining concentrated wort was diluted with store brand purified water to a total volume of 5 gallons. Samples were taken from this diluted wort and reheated for specific heat testing and one sample was set aside to cool to test specific gravity.
(Data collection) When measuring masses, record data accurate to hundredths of a gram. When measuring temperatures, record data accurate to tenths of a degree. Measure and record mass and temperature of an approximately 50 gram sample of chilled deionized water. Measure and record mass and temperature of an approximately 50 gram sample of wort. Combine the two samples in a foam cup calorimeter, then measure and record the temperature of the mixture at equilibrium. Repeat this procedure for a total of three trials for concentrated wort, then repeat for a total of three trials for diluted wort. Cool a sample each of concentrated and diluted wort to 60*F to measure and record specific gravity.
Data:
Specific Heat of Wort (A Scientific Approach)
q=mc(deltaT)
all masses in grams, all temperatures in degrees Celsius
specific heat in J/g*C (specific heat of deionized water = 4.18)
method of calculating was:
m(wort)*c(wort)*[Ti(wort)-Tf] = m(water)*4.18*[Tf-Ti(water)]
{solve for c(wort)}
*(I used underscores to try to preserve the table format here, since it seems the forum software doesn't like me pasting in something copied from a spreadsheet.)
Concentrated Wort -
________mass di___temp di___mass___temp___temp______specific heat
________water_____water____wort___wort____mixture____of wort
Trial 1___55.12_____8.3______52.73___76.4____39.9______3.8
Trial 2___59.32_____8.1______52.27___78.0____38.3______3.6
Trial 3___57.02_____8.4______64.56___73.5____41.7______3.9
_______________average of specific heat from all 3 trials:___3.8
concentrated wort specific gravity: 1.190
* Please see comment in notes!
Diluted Wort -
________mass di___temp di___mass___temp___temp______specific heat
________water_____water____wort___wort____mixture____of wort
Trial 1___59.32_____8.4______63.65___78.6____42.3______3.6
Trial 2___64.78_____8.3______53.64___72.3____34.9______3.6
Trial 3___51.34_____8.4______64.35___67.4____39.0______3.6
_______________average of specific heat from all 3 trials:___3.6
diluted wort specific gravity: 1.061
Conclusions:
The results of this experiment were, quite frankly, a surprise. The specific heat of concentrated wort is 9.1% less than the specific heat of deionized water, and the specific heat of diluted wort is 14% less than the specific heat of deionized water. Not only was the difference three times what was anticipated, but the difference was in the opposite direction from what was anticipated. Upon inspecting the results and contemplating the cause of the difference in specific heat, a possible explanation would be that the sugars and other compounds present in the malt extract act as very good conductors of heat. If this were the case, then one might expect the specific heat of concentrated wort to be lower than the specific heat of diluted wort, yet this is contrary to what was found. Granted, the difference between the specific heat of concentrated and diluted wort is only about 5%, but it is measurable difference.
Notes:
In reference to the concentrated wort specific gravity listed on the data page, when this measurement was attempted it was quite literally off the scale of the hydrometer used. By inspecting the scale of the hydrometer and extrapolating the scale beyond the markings provided, the reasonable estimate of 1.190 was deduced. I felt it relevant to include the specific gravities because this is a measurement frequently used by brewers and would make for a convenient reference point when comparing the concentrated wort to the diluted wort.
Lastly, I do want to acknowledge that the type of specialty grains used as well as the type of dry malt extract and variety of hops used were omitted intentionally. The reason for omission was to keep this experiment and any discussion of this experiment focused strictly on the difference between the specific heat of wort and specific heat of distilled water and to avoid discussing opinions of my recipe. Additionally, I acknowledge that these variables could very well affect the specific heat of the wort, and may come into play in a future experiment, but that was simply beyond the scope of what I had the resources to test at the time of this experiment.
Thanks for taking the time to read this, I really enjoyed putting it together!