Transcript Dorito`s Lab explained

Dorito’s Lab
NOTES
Read before you do the lab
Doritos’ Lab
This lab will help us grasp the connection between food and calories (energy).
We’ll use dorito’s because we have to use something, and the chips burn
easier than bananas. Plus, it’s a shame to burn bananas.
Dorito’s come with a food label, because by law all packaged food must tell us
what we’re actually eating.
Let’s look at the label now. It says that one serving is ___ g.
It also says that one serving has ______ Calories.
Those are the big ones, capital C, kilo-calories. No one really ever eats one
serving, so the labels are legally correct but nonsensical in our real world. But,
this information will be used by us, conversions await, to turn these “Calories”
into energy, which is what food is.
Food is energy. You can use it, or store it, depends upon how much work your
body does once eating these Doritos. We’ll use one whole chip per pair of
students for this lab. Leftovers can be eaten, if you dare.
Bomb Calorimeters
To calculate how much energy is in food, a fancy device called
a bomb calorimeter is used. It indirectly measures the energy content
(which is converted from joules, to calories to kilocalories). We will
“make” one of these in lab later, but not so fancy. We’ll do the exact
same process as used in a nutrition lab with a $9000.00 device, but
we’ll have more percent error.
On the next slide is a diagram of a bomb calorimeter, and it’s
necessary to understand how it works so you can construct one
yourself.
What you need to measure in a bomb calorimeter.
Mass of food sample
Mass of pure water in grams
Start temperature of pure water
Final temperature of pure water after burning food
Using our basic heat formula, q = mCΔT, we can fill in our variables and
calculate the joules of energy that the water gained.
Most important question: Where did the energy to heat the water come from?
We will make a “calorimeter” now.
You need a can and a thermometer. A ring stand and a glass rod.
And some water. Also a piece of Aluminum Foil to direct the heat.
Crucible tongs will be needed to hold the chip.
This “Calorimeter” will not be an
exact instrument, and your
percent error will be enormous.
Nonetheless, this lab will make
you “DO” exactly as you would in
a nutritional lab, calculating the
energy stored in Doritos’ chips.
Everything is just a conversion
away. Hair up, fire hot, goggles
on. Don’t eat burnt chips no
matter how odd you are, they’re
gross.
If you’re under
50% error: great!