Lab 5.1: Alka Seltzer Poppers

In our experiment, we recorded how long it took for a tablet of Alka Seltzer to build up enough pressure to pop the top off of a small canister. We changed around things like temperature, how crushed the tablet was, and the ratio of vinegar and water in the film canister. Our procedure was effective at determining how different variables affected the rate because we made the variables very far apart (For example, instead of putting 24 degrees Celsius and then doing 25 degrees Celsius, we did 0 and then 50.) It was important to keep a control, and only change one thing at a time. If we changed two variables at a time, we wouldn't know which contributed more to the cap popping faster or slower.

A higher temperature made the particles move faster, which gave them a higher chance to collide at higher speeds. The more the tablet was crushed, the faster the reaction rate, because there is more surface area for the vinegar to touch the Alka Seltzer. The more vinegar put in, the faster the reaction rate, because vinegar is a better reactant than water, and the water molecules just get in the way of the vinegar molecules touching the tablets. Our concentration of vinegar in our experiment was not consistent. We thought more vinegar would cause a faster reaction rate. Our data was misleading because we didn't push the top on hard enough, so it didn't create a good seal. Without the seal, air can escape, and not as much pressure will build up.

Enrichment: Sulfuric acid is a catalyst used in real life, It's a highly corrosive mineral acid. It is used in batteries for cares, and for oil refining.
                    Almost all enzymes are proteins. They speed up chemical reactions by converting substrates into different molecules, called products.

Lab 4.2 Heating And Cooling Curves Of Lauric Acid

The melting point of the lauric acid on the given graph was about 45 degrees Celsius. The freezing point of the acid on my graph was around 42 degrees Celsius. These two temperatures should be the same. There may be a slight difference in temperature based on the conditions. It would be extremely difficult to heat a solid above its melting point because the heat that enters the solid at it's melting point is used to convert it into a liquid. Although, you can cool a liquid under its freezing point while staying in liquid form by supercooling it (I researched this a little). A liquid can be supercooled because the particles are packed in an odd way that is not characteristic of the liquid. I got the freezing point from my data by looking where the graph sort of leveled out, because when the substance freezes, it's temperature stays relatively the same for a short time.
                         Kinetic energy is the energy an object (in this case the lauric acid molecules) has when it is in motion. Temperature is a measure of average kinetic energy, so if the temperature increases, so does the kinetic energy, and vice versa. Since temperature doesn't change during melting or freezing, potential energy is the energy that is gained or lost during this process.
           Enrichment: The actual melting point of lauric acid is 43.2 degrees Celsius. Our melting point was recorded at 44.5 degrees Celsius. My percent error is calculated to be 3.01%. This may be because the pressure in the chemistry room may have been slightly different than wherever they recorded the actual temperature. (I'd assume they took it at standard pressure, 101.3 kPa, just to be accurate.)
The chemical formula for lauric acid is C12 H24 O2. Lauric acid is used in the lab to find out the molar mass of a substance, using freezing point depression. Freezing point depression is when the freezing point of a liquid is depressed when another compound is added, which means the mix all together will have a lower freezing point. I got all of this from right here.

Blog 4.1 Fun With Air Pressure

1. A decrease in pressure causes the volume of a balloon to increase. This is because there is less pressure pushing on the balloon, so it is free to expand.

2. Adding more gas to a bottle increases the pressure in that bottle. More gas takes up more space, so in order for the bottle to have all of that gas, it needs to compress it more, thus creating more pressure.

3. As the volume of a cylinder is increased the pressure will decrease. There is more room for the molecules to move around and not be as compressed, so the pressure will decrease.

4. Increasing the pressure in a tire by adding more gas will cause the volume to increase. When gas is in the tire it will inflate a little bit to hold all of the gas, like a balloon.

5. As the temperature of a closed container of water is increased the amount of water vapor  above the water causes an increase in vapor pressure. the more gas that is created, the more it will push on the water underneath it.

                                        

6. As the air pressure above a liquid is increased by adding more air, the boiling point of the liquid will increase. The higher the pressure, the more energy it takes to boil the liquid.

7. If a balloon filled with air is taken under water to a depth of 10 feet, it’s volume will decrease. This is because of the pressure of the water pushing on the balloon.

8. The temperature of a beaker of boiling water will increase as more heat is added. This is true because temperature is a measure of heat. So if there's more heat, the temperature is higher.                                                                          

 

9. Hot air rises because it is less dense the cold air around it. Since it is less dense, its molecules can easily get by the cold air.

                                                 

10.  When heated, the volume occupied by air in a balloon  will increase. Heating a balloon would cause the gas molecules inside of it to start moving faster and taking up more space.

Most of my predictions were correct, but some were not. It surprised me that the temperature of the water didn't change when put in the vacuum. I thought the temperature would decrease. What surprised me even more was the fact that it started boiling. Before, I thought you had to have heat in order for liquids to boil.

Enrichment: The workers created a vacuum by sealing off the tanker, with all of the hot steam inside of it. When the temperature dropped, the pressure changed so quickly that it crushed then tanker. This is similar to what we did when we flipped the can with boiling water into the ice water.

Lab 3.1: Properties of Ionic and Covalent Compounds

1. Ionic compounds generally have a high melting point, dissolve in water, and conduct electricity.
2. Covalent substances generally have a low melting point, don't dissolve in water, and don't conduct electricity.
3. Ionic bonds form from a metal and a non metal. The electrons are transferred.
4. Covalent bonds form from two non metals. The electrons are shared.
5. Covalent bonds don't conduct electricity because the electrons are fixed in one place and can't move freely.
6. When in solid form, ionic substances electrons can't move freely. Dissolving them separates the ions and allows them to move around.
Enrichment: When athletes sweat, they lose electrolytes. These electrolytes are needed to perform muscle function. The most commonly used electrolytes are dissolved metal salts. Some electrolytes used are Potassium, sodium, and chloride.

Lab 3.1: Modeling Molecules

1. I think the bond between ions is stronger than the bond between molecules because most ionic bonds have a higher melting point. Ionic bonds are also electrically attracted to each other, while molecules are not.

2.When you melt something, it's a physical change. Physical changes don't rearrange the atoms, chemical changes do. Therefore if you melted HCl molecules, they would not seperate.


3. When ionic substances are melted, the molecules are free to move around and create a charge.

4. Molecular substances do not create a charge because molecules have a neutral charge.

 Enrichment:
                    A polar molecule is a molecule with a bond from having two atoms with opposite charges. Water is a polar molecule.

Blog 2.2 Bag of Ions and Periodic Table

             The periodic table is arranged by groups and periods. The groups are vertical columns that go by number of valence electrons. The periods are horizontal rows that increase going down in number of electron shells. The noble gasses are all on the right side, and they have full valence electron shells.

   Ions of the same element have the same number of protons and mass, but they have a different number of electrons, valence electrons, and neutrons. An ion is formed when an element gains or loses electrons. If it loses electrons, it becomes more positively charged, as electrons have a negative charge. If it gains electrons, it has more of a negative charge. If you look on the periodic table, you will see the elements electron configuration. This also shows how many valence electrons an element has. You can see the charge in the top right corner.

Lab 2.1 Grouping of Elements

1. The groupings of elements we made were:
Aluminum and lead
Carbon, Silicon, and Tin
Sulfur and phosphorous.

2.Appearance- Physical. It doesn't have to do with anything chemically, it's just how it looks.
   Electrical conductivity- Chemical. Depending on what kind of atoms make up the element decides if it will hold an electric current.
   Crush Test- Chemical. It depends on how tightly the atoms are packed together.
   Reactivity With Acid- Chemical. An element reacting with something is a chemical property because it depends on how the atoms are formed.

3. A. What is unique about metalloids is that they can have properties of both metals and non metals, depending on the conditions.
   B. Silicon. It is shiny, has some electrical conductivity, is brittle and does not react with acid.
   C. Boron- B, Silicon- Si, Germanium- Ge, Arsenic- As, Antimony- Sb, Tellurium- Te, and Polonium- Po.
 
4.From top to bottom, the elements go from shiny to dull.
   From right to left, the elements go from dull to shiny.

Enrichment:
           Silver-Ag comes from the latin word argentum, which means 'white metal' in English.