Chemistry Test Review

My assigned question was #25.
Write the set of quantum numbers for the last electron placed for:
a) S^2-    b) Pb      c) Au     d) W     e) P    f) Ba^2

Answers:
a) (3,1,1,-1/2)
- Equivalent orbital diagram to Ar
b) (6,1,0,1/2)
c) (5,2,2,-1/2)
- Has the "d-block" exception applied
d) (5,2,2,1/2)
- Has the "d-block" exception applied
e) (3,1,0,1/2)
f) (5,1,1,-1/2)
- Equivalent orbital diagram to Xe

Cocoa Powder

     I decided to observe the physical and chemical properties of Hershy's Cocoa Powder because I love chocolate milk, chocolate brownies, and anything that has cocoa powder in it!
     For my physical properties, I decided to observe the substances color, taste, phase, malleability, and the composition of the substance. I chose to do these five observations because the color, composition, and phase are obvious once the container is opened; then I decided to do the taste and malleability of the Cocoa Powder because I was curious of the results.
     For my chemical properties, I decided to conduct expiraments on the flammability, reactivity to acid, sensitivity to light, oxidation, and reactivity to water of the substance simply because I was curious about the results!
     Each conclusion that I came to is a result of observing the substance and also the substance's ability to change its original identity to form a new substance.

Chemical Properties:

Chemical Properties: relates to a substance's ability to undergo changes that transform it into different substances.
(definition comes from page 8 in the textbook)


Flammability:
For this test, I carefully placed a flame on the cocoa powder. I know flammability is a chemical property because flames can potentially change the original substance to a new substance.

Flame and Cocoa Powder

At first, the cocoa powder looked like it was burning because the color of the powder started to turn black. Then when I took the flame away from the cocoa powder I noticed a trail of smoke coming off the powder.

Cocoa Powder and Trail of Smoke

Then I began to blow on the cocoa powder because I was curious to see what would happen. To my surprise, the cocoa powder actually had embers in it. So the cocoa powder is indeed flammable.

Embers appeared when I blew on the cocoa powder.

Reactivity with Acid:

First, I mixed a little vinegar with some baking soda. Then I added half a teaspoon of cocoa powder to the mixture. I observed that some bubbles were forming and that was about it. Nothing else noticable happened after the bubbles formed. I know reactivity is a chemical property because when two or more chemicals react, a new substance can potentially be created.

Bubbled formed.

Oxidation/ Sensitivity to Light:

     According to http://www.enotes.com/science-experiments-projects/chemical-properties/what-some-examples-chemical-properties, oxidation is the ability to react with oxygen which is a chemical property. Some examples of oxidation are a sliced apple turning brown or iron rusting. For this test, I left the cocoa powder container opened overnight. The cocoa powder did not in any way react with oxygen. 

     According to http://www.enotes.com/science-experiments-projects/chemical-properties/what-some-examples-chemical-properties, sensitivity to light is a chemical property. An example of this is that newspapers turn yellow because they are sensitive to light. For this text I put direct light on the cocoa powder or three hours and observed any noticable changes. Then I put the cocoa powder in complete darkness for three hours and observed for any noticable changes. The cocoa powder did not react to light or darkness. The color remained the same.

I placed a flashlight on the powder for a consecutive three hours to observe the chemical property of sensibility to light.

Reactivity with Water:

First I filled a small glass with about one tablespoon of water. Then I added one teaspoon of cocoa powder. I observed the mixture for a couple of minutes and I noticed that the cocoa powder was slowly mixing itself with the water. Reactivity with water is a chemical property because when a substance is mixed with water, a new substance can be created. In this case, when I mixed cocoa powder and the water, a new substance was made, a muddy liquid.

Physical Properties:

Physical Property: a characteristic that can be observed or measured without changing the identity of the substance.
(Definition found on page 7 in the textbook)


Color:

First, I opened the Hershey's Cocoa container and came to the conclusion that the color of the Hershey's Cocoa powder is a light brown. Color is a physical property because color can be observed without changing the identity of the substance.

Hershey's Cocoa Powder: Color Observation

Taste:

Next, I tasted the cocoa powder. There was not a strong taste to it like I expected but there was definitely a bitter taste to the powder. Taste is a physical property because taste can be observed without changing the identity of the substance.

Phase:

After observing the shape and volume of the cocoa powder, I concluded that the identity of the substance is a solid at room temperature because it has a definite shape and a definite volume. Phase is a physical property because the phase of the substance is observed and is not changing the identity of the substance, which is a solid.

Homogeneous:

The cocoa powder is homogeneous because the composition of the cocoa powder is uniform throughout the substance. To be homogeneous the matter must be a mixture and be uniform in composition. This is a physical property because the composition can be observed without changing the identity of the substance.

Homogeneous- the composition is uniform throughout.

Malleability:

For this test, I took a Chinese chopstick and crushed the cocoa chunks and observed what happened to the powder. The bigger chunks just broke up into smaller chunks until finally it all became a fine powder. So the cocoa powder is not malleable. Malleability is a physical property because it can be observed without changing the identity of the substance.

Malleability Test