Category: Chemistry

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S’more Stoichiometry Lab

FUN! FUN! Another day for Lab! FOOD!

You’ve ever cooked a meal from a recipe, you will have noticed they come with serving amounts, in fact, this number can be off, and you’ll end up with either less or more food than you anticipated. A number of things can take an account for this difference – food spillage prior to cooking, leaving ingredients too long on the stove top, using the wrong measuring cup, and so forth.

The similar can happen at whatever point we have an experiment in the chemistry lab to make a compound. We first make a calculation for how much of a compound we’ll end up with, in fact, these calculation are made under ideal conditions. They don’t account for experimental errors or personal errors of the experimenter. In the end, your prediction is often different from what you have actually made.

In Chemistry, we have learned about theoretical yield, which is the amount of the product calculated from the limiting reactant. The limiting reactant is the reactant in the chemical reaction that limits the amount of product that it can produce. The actual yield is the actual amount of the product, which the experiment produces.

The difference between theoretical yield and actual yield can be calculated by using percent yield, which we can use this formula:

In order to use this formula, the theoretical yield and actual yield need to have the same unit. If the actual yield in gram, the theoretical yield also need to be in gram. If the actual yield in mole, the theoretical yield also need to be in mole. If one has a different unit, we need to perform a conversion if we are giving one measurement in term of the unit.   

We had conducted an experiment (S’more Lab). In order to make this S’more, we need substance, so teacher provide us Cracker, Chocolate, and Marshmallow.

Substance Symbol
Graham Cracker (half of a cracker) Gc
Marshmallow M
Chocolate Piece (individual piece of chocolate) Cp
S’more  (2 crackers, 3 pieces of chocolate, 1 marshmallow) Gc2MCp3

We need to follow a certain step to create S’more

Step 1: Balance the equation

Cp + M + Gc → Gc2MCp3 to 3Cp + M +2Gc → Gc2MCp3

Step 2: Calculate the theoretical yield 

In the experiment, I weight the substance. I got Graham Cracker (Gc) 8 grams, Marshmallow (M) 5 grams, Chocolate Pieces (Cp) 9 grams. I added all up, it has 30 grams of the substance 

Step 3: Roast your marshmallows and chocolate on the Bunsen burner

Roasting Chocolate on a burner

Step 4: Putting the marshmallows and the chocolate between the cracker

Placing marshmallows and chocolates on top of the cracker

Step 5: The ACTUAL (experimental) mass of one s’mores: 28.5 grams

Taking an average of three Smores (28.5 grams)

Step 6: Calculate the percent yield

Experimental Yield = 28.5 grams

Theoretical Yield = 30 grams

% yield = (Actual yield / Theoretical yield) * 100

28.5/30 = 0.95 * 100 = 95%

Percent yield = 95%

Step 7: EAT YOUR S’MORE!!! (:

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Flame Change Color When Have Contract With Chemical!

When an element get heated with the flame, heat will excite the electrons in the atom.  This allows the electron to travel from the ground states to a higher energy level. So the atom becomes unstable and it will release energy to move into it ground stand back. In this releasing energy will match wavelength that it will energy emit and it also corresponds to the color of the visible light in a form of electromagnetic radiation.

I had an explanation about the concept of the idea with word now how can we see it with our eye, so we need to conduct an experiment that called the flame test lab in our chemistry class.

The Copper salt with flame, it produces a Pastel Green color. This Pastel Green had a wavelength between 495-570 nm.

In the experiment, we had six different compounds of salt (Copper, Strontium, Barium, Lithium, Calcium, and Potassium). Each of them was placed on a popsicle stick that will be heated on the flame of a burner. All of the salt compounds emitted different colors and then we find the wavelength that corresponds to the color of the salt compound that was identifies.

Nevertheless, in an experiment, they would not be conducted with a perfect resolve. One possible source of error can be how we observed the color. Color is really tough to identify with our eye. This would lead us to an inaccurate of the color, that would affect the wavelengths we would find at the end. In the next experiment, I would avoid this error by using colorimeter can be used to accurately measure the wavelength.