Has anyone evaluated the equations found in the 2017 power point on Soinc.org/food science?
I have asked a chemical engineer to assist us with the equations. He looked at the power point and shook his head at the manner in which it was written.
I would suggest not using that; the rules call for joules/gram. However, if you want to find calories, here's the equation I use...
Q=m*c*ΔT. Q is the number of calories, m is the measurement of water (in grams, 1 mL = 1 gram), c is this equation: 1 calorie/gram*degree Celsius, and ΔT is the temperature of the water before burning subtracted by the temperature of the regular water (this is in degrees Celsius) (for example, 40-32=8).
If you want to convert calories to calories/gram, find the mass of the food before burning and divide the calories (what you just got) by that mass. Also, 1 cal/g = 4.1868 Joules/g.
I agree the powerpoint is not very clear with the calculations for calibrating the device and for using it in testing. It is probably clear to those with good understanding of the concepts, but for many of us, like me, we are left scratching our heads.
My questions is this: the letter c in the equation, is that a constant for water?
The powerpoint has it equal to two values: 4.18 J/(g degK) and 1.0 cal/(g degC). Is that correct? Should the degK be degC?
I appreciate those who took the time to put the ppt together to try to help, but my density is very high and my heat of combustion is....not constant.