Blog Post #8!!

This week and the end of last week in SG Chem1, the main ideas were all connected through energy. We mostly worked with two types of energy: thermal and phase. Thermal energy is represented in degrees Celsius, and phase energy is represented in bars on a bar chart. One bar represented a solid, two a liquid, and four a gas. Here is an example of a bar chart:

As you can see, the Eth stands for thermal energy, and the Eph is phase energy. Ech stands for chemical energy, but we didn't really go over that in class. Let's go over how to do an energy bar chart problem.

The directions were: For each of the situations described below, use an energy bar chart to represent the ways that energy is stored in the system and flows into or out of the system. Below each diagram, describe how the arrangement and motion of the particles change from the initial to the final state.

The situation for problem one was: A cup of hot coffee cools as it sits on the table. As pictured in the photo above, we labeled the first line 0 degrees Celsius (water's freezing point), the second line 25 degrees Celsius (room temperature), the third line 60 degrees Celsius, and the fourth line was 100 degrees Celsius (water's boiling point). We filled in four bars of thermal energy on the initial graph, assuming that the cup of hot coffee was near water's boiling point, and then on the second graph, filled in two bars, because the coffee would probably cool to room temperature. Next, phase energy. As previously stated, liquid is represent with two bars, so we filled in two. We agreed that the phase of the water would not change, so we filled in the same two bars on the final graph. We subtracted the amount of energy bars on the initial graph (six) from the amount on the final graph (four), and we got a difference of negative two energy bars as the event occurred. If the circle between the two graphs is the system of the event, and the event lost two bars of energy, then the arrow with the two bars represents the two bars leaving the system. This is because a large amount of the heat energy of the coffee left as the temperature cooled.

Most of what we did this week was these problems. We whiteboarded them often and had a lot of board meetings. One question I still have from this week is: are the bubbles from boiling water really made up of water vapor? Not air? When we blew bubbles as kids, were the bubbles we blew made of vapor from the bubble solution? Or the air we breathed out? As you can tell I have lots of questions about the bubbles. I participated a lot in learning this week. I really like my table because we're all eager to learn and understand the material we're given, and I think that's really cool. I think I understand the information from this week pretty well.

Post #7 !!

This week in SG Chem 1, we did a lot concerning the pressure, temperature, volume, and particles in a gas. These were the main ideas. They're connected because they're all measurements having to do with a gas. Some important details to these main ideas are that standard pressure is 1 atmosphere, and standard temperature is 0° Celsius, or 273 Kelvin. We normally use Kelvin to measure temperature of a gas because Celsius that could cause a negative pressure, volume, or number of particles, and that's not possible. 

We did a lot of worksheets measuring different variables of a gas. Let's look at one of our problems as an example:

You fill in the initial row of your graph with the measurements the gas starts with. You have to change the 25° Celsius to Kelvin, so you add 25 to 273. That gives us 298 Kelvin. A number of particles is not given, so that variable is constant. For the final row, you fill in the set of measurements for after the pressure and temperature are changed, which would be 760mm (or 1 atmosphere) and 273 Kelvin (the standard temperature). Then you fill in the effect row with the change that's happened. If the number went down, you write a down arrow. If it went up, write an up arrow. Since pressure went up, we can assume that the volume will go down, because they're inversely proportional, and since the temperature went down, the volume will again go down because temperature and volume are directly proportional. Fill in those arrows and move on to the equation. You have to multiply your initial volume by your initial pressure over your final pressure (so the volume will decrease), and your final temperature over your initial temperature (so the volume will decrease again). The equation ends up being 250 x 730 x 273 ÷ 298 ÷ 760 when you type it into a calculator. Hit the enter button and the answer comes out to be 220 cubic centimeters.

We did an experiment we did today involving pressure. Mr. Finnan put a blown up balloon in a sealed space and slowly sucked the air outside the balloon out of the space with a vacuum. The balloon grew until it eventually popped. The reason this happened was the pressure outside the balloon was decreasing and inside the pressure was increasing until it popped.

This week we also went over what we've done so far in class this unit. A whiteboard containing all that information looked like this:

Our class has gone over a lot about particle movement and movement of a gas this unit. We've done a lot of experiments involving gas and measuring it. We've learned how to measure the pressure, volume, temperature and number of particles of a gas in many different situations. 

I don't have many questions about what we learned this week, I think the worksheets we did explained everything pretty well. My participation this week was pretty good, that's how I came to understand this material so well. What I would work on more is knowing how measurements are related when not related to pressure, like temperature to volume or volume to number of particles. It was interesting to learn about the kinetic molecular theory and how gas particles are randomly spread out, and just more about gas in general.

Blog Post #6

The main ideas in SG Chem1 this week were pressure and particle movement. Pressure is the force applied to an object. We measure pressure in atmospheres (atm). Particle movement and pressure relate because they both relate to energy and temperature. Particle motion always involves energy and pressure is energy per unit of volume. We also did experiments on these subjects, too. We measure temperature in degrees Celsius or Kelvins.

We did an experiment early in the week where we put Luke on an inflatable raft and four students blew air into the raft to inflate it. Then we whiteboarded the experiment. It explained a lot about particle movement. Air particles are moving randomly in the air at all times. Then when the students blew air into the raft, the amount of force exerted outward from the raft, or the pressure of the molecules pushing inside of the raft is larger than the force of gravity pushing Luke down. Here is a video of the students blowing Luke up:

The rest of the week, we did three important experiments involving pressure. We compared pressure to temperature, number of particles, and volume. 

For the pressure to temperature experiment, we attached temperature and pressure sensors to a computer and used LoggerPro to record our information and measure the pressure and temperature. We put a temperature probe in a beaker and added hot water to cover most of the flask we put in the beaker. We then recorded the temperature. Then we repeated the process with cooler water, ice water, and alcohol with ice in it. We predicted that, as Pressure as the y-axis and Temperature as the x-axis, the line on the graph would go up and to the right, and we were correct.

On the second experiment, pressure versus number of particles, we attached a pressure sensor to our computer and hooked up LoggerPro. We measure the number of particles in puffs, and again predicted that, as Pressure as the y-axis and Number of Particles as the y-axis, the line on the graph would go up and to the right. It did.

For the third and final experiment, we again attached the pressure sensor to our computer. We then attached that to our syringe. We started at 14 mL, recorded the pressure for that, then slowly pushed down to 12, then 10, 8, and 6. We predicted that with Pressure as the y-axis and Volume as the x-axis, the line on the graph would be straight and go down and to the right. We were close, except the line was curved. 

From these experiments, we concluded that pressure is inversely proportional to volume, directly proportional to number of particles, and directly proportional to temperature. 

One question I have from this week is: how is force different from pressure? I know pressure is a force, but then why not just call it force? Is all pressure force, but not all force pressure?

I participated thoroughly during the experiments this week and feel I have learned a lot about particle movement, energy, and pressure. 

Post #5

On Monday in SG Chem1 we presented our whiteboards of what we have done so far in the class. Here is one table's presentation:

So far, we've learned a lot about mass, volume, density, and measuring them. To measure mass, we used grams, for volume we used mL or cubic centimeters, and for density we used grams per mL, or mass per unit of volume. Knowing this information is important for measuring objects, especially knowing mass, because all matter has mass.
We've covered a lot about mass and change, and learned about what happens to the mass of a substance when you dissolve it (the mass is unchanged), or when you burn it (the mass increases in size).
We've also learned about significant and estimated digits in a number. We've also learned about significant zeros and their five rules:
1. All non-zero numbers are significant. For example, all the digits in 155 are significant.
2. Sandwiched zeros are significant. For example, the zero in 101 is significant.
3. Zeros that are only placeholders for a decimal aren't significant. For example, the zeroes in 200 aren't significant.
4. Zeros at the end of a number that also contains a decimal are significant. For example, the zeros at the end of 0.400 are significant.
5. Exact numbers have an infinite number of significant zeros. For example, if there are 13 people in a room, then that number, 13, has an infinite number of significant zeroes.
It's important that we know when zeros and digits are significant and when to use an estimated digit for measuring objects. For example, when measuring the side of a piece of wood with a ruler that only has dashes for inches, you'll have to record how many inches the side is, and then add one estimated digit which is more specific than the inch, in order for the information to be correct.
We had a unit exam on Tuesday covering all of what we learned, and then we started on a new concept: particle movement. We only covered this concept on Thursday and Friday, but we were able to fit in two experiments.
For one experiment, Dr. Finnan stood in the corner of the room and opened a bag of popcorn. He asked us to raise our hands when we smelled the popcorn odor. The tables closest to him raised their hands first and that hand raising steadily spread to the tables in the back. This proves that particles move because the popcorn odor particles got all the way from one side of the room to the other.
The next experiment we did included two beakers of water, one hot and one cold. We dropped one drop of blue food coloring into each and then watched its movement. This is a video of the event:

As you can see, in the hot water, the coloring spread much quicker than in the cold water. Our table concluded that the energy from the hot water allowed for the particles in the food coloring to move more fluidly throughout the water, while the lack of thermal energy in the cold water caused the particles to move more slowly. From this experiment, we learned that heat energy exists.

We also watched some videos explaining molecule movement in solids and liquids. In solids, molecules don't move too far away from each other, while in liquids they move very far and the attraction between two molecules isn't as strong. The molecules bounce all around inside the substance. 

Particle movement and energy connect because particles have energy. Every moving thing has energy. An important detail to particle movement is that it moves differently depending on what state of matter an object is in. Particles move quicker and further in liquid and gaseous forms, and less so in solids. When affected by heat energy, particles move quicker. My participation this week was pretty good, and I learned a lot about the material we're being taught. I don't have many questions about what we learned this week, but I would like to learn more about heat energy and how it works. 

SGChem1 Post #4

The main ideas this week in Chemistry continued to mostly be relating to density and measurement. One of the main experiments we did was we measured the density of gas. We began the experiment with a plastic squeeze bottle. We filled it full of water and put it in a basin of red water. We stuck the end of a small tube in the bottom of it. The other side of the tube was connected to a container.

We put a small plastic squeeze bottle with water inside and a cup with an Alka Seltzer in it onto the pan of the balance. Together, it all weighed 72.195 grams. Then, we dropped the cup with the Alka Seltzer into the bottle of water. Gently, we swirled it around. Pretty soon, it started reacting. We waited for approximately 10 minutes as the gas collected in the container. We again measured the mass of everything, which was 71.715 grams. So, puzzlingly, the solution lost .48 grams. We also calculated the volume of the gas, which was 295 mL, which confirmed that the density was .00163. So now we know how to calculate the density of a gas.
One question I still have about this is why did it lose mass? I understand that a chemical reaction probably occurred, causing mass to be lost, but it would interesting to learn exactly what happened.
Another experiment we did in class involving measurement was one where we tried to find the thickness of two pieces of aluminum. We massed the first piece of aluminum and it was 2.62 grams, while the second piece was 2.46. The density of both was 2.7 grams. The surface area of the first piece was 597.36 cm, and the second piece had a surface area of 580.72 cm. So for each piece, we divided the mass by the density and surface area to get the thickness. The thickness of the first piece was .00162 cm, and the second one was .00157 cm.
The important details to the main ideas continue to be units. You have to always be sure of the units you're using. For density, the unit has usually looked something like this: g/mL.
My participation this week was pretty thorough, although in our group, a certain person usually tries to take over everything, and he doesn't really give anyone else a chance, but we're working on that.
I would rate my understanding of what we did this week as a 10/10. We go over everything in class very well and instruction at the beginning of class is very clear and easy to understand.
In the future, I'll work on precision in my calculations, because a lot of the time at our table, the errors we make are calculation errors. It's important to write all our work down, so we don't lose it!
Other than that, the information we learned this week was clear and helpful for further measuring instances.

Blog Post #3

This week in SG Chem1 the main ideas we looked at were mass, volume, and density. On Monday, we measured an amount of water in a cubic container and a graduated cylinder.

For measurements on the cubic container we used cubic centimeters and we used milliliters for the graduated cylinder. We made a chart and it became apparent that milliliters are equal to cubic centimeters. Our chart is pictured below.

Milliliters and cubic centimeters are both used to measure volume. Volume is the amount of space that an object occupies. When using a graduated cylinder to measure volume, you can often use uncertainty to express that the measurement could be greater or less. If you use uncertainty depends on the graduated cylinder you're using.
Mass is the measure of the amount of atoms in an object. To measure this we used grams. We used a scale to measure the mass of five rods of steel, acrylic, and aluminum. We also measured their volumes. Then we put these measurements into a graph to compare the volume to mass using LoggerPro. We looked for how much mass per volume there was. That's the density of an object. This is our graph:

As you can see, g/mL, or the density, is written for each line. This is the slope of each line, rise over run. The densities for each material differ greatly. In class, we went over the densities. Our table's information turned out to be outliers, but the steel had the largest density, and the acrylic had the least, according to the class. The graph is below. We're table 6.

On Friday, we went over problems from a worksheet in class. One problem we went over said something like this: Object E is the same volume as Object F. The particles in Object E are larger and therefore have more mass, but are uniformly distributed throughout the object. Compare their densities. 

After reading this problem, we worked out what we thought our answers were on whiteboards, then had a board meeting. My group's first answer was that Object E and Object F had the same density, because they had the same amount of particles per unit of volume. However, then we realized that, since the particles in Object E were bigger, the object literally had more mass per unit of volume, which would alter the density. 

Since some of the class refused to admit that Object E had more mass, the problem went unsolved, but I believe that our answer is correct based on what we know about density and what it is.

The main ideas this week connect because they're all used to measure. To measure the mass of something is to measure the amount of particles it has, to measure volume is to measure the amount of space an object takes up, and density is the measurement of how much mass per volume there is in an object. Some important details to these main ideas include units of measurement, such as grams (mass), cubic centimeters (volume), and milliliters (volume), and knowing how to use a scale, knowing how measure using a graduated cylinder and knowing what uncertainty is. 

I don't have many questions about what we learned this week, but one that I do have is: did Object E have a greater density than Object F? It would be great if we went over that again.

In the future in these topics I think I need to work on measuring more carefully, so we don't have ridiculous outliers like we did this week.

SGChem1 Post #2

This week in SGChem1, we reflected on the Mass and Change Lab. We got into our groups and worked on whiteboards to try and figure out what happened during the remainder of the stations in the lab. Here are some examples:


We did one experiment with Alka Seltzer where we massed the Alka Seltzer and some water, then dropped the Alka Seltzer into the water. The solution lost half of a gram.
From this experiment I concluded that when the Alka Seltzer dissolved into the water, some of its particles became lighter than the water particles and they rose out of the water and into the air. That's my theory. I still wonder why not all of the Alka Seltzer particles rose, and why the mass didn't have a greater change.

The next experiment we reflected on was the Calcium Chloride/Sodium Carbonate station.

In our group, we mixed the two chemicals and the solution lost 11.7 grams. We later learned that that was because we didn't mass the vials. Most of the rest of the class's mass didn't change, though. So we can assume that not much happened when we mixed the two chemicals. Some of the other boards did show that some kind of reaction happened and part of the solution became denser and sunk to the bottom of the vial. So maybe the Calcium Chloride particles bonded with the Sodium Carbonate chemicals. Our group would have to retry the experiment to get sufficient results.

And the last experiment we reflected on this week was the one where we burned steel wool. This experiment confused all of us, because you wouldn't expect something to gain mass after it's burned. But we suspect that when we burned the wool, a chemical reaction occurred, creating new particles with a bigger mass. Our wool gained 0.2 grams.

I learned from the Mass and Change Lab that the mass of something before and after an event occurs cannot easily be predicted. It takes experimentation and questions to find answers.

Besides that, the main ideas from this weak were mostly along the lines of measurements. We learned about valid measurements. A measurement should have one estimated digit. The estimated digit should be the last digit in the measurement. The estimated digit should correspond to one tenth of the smalls marks. For example, if you're using a ruler with only centimeter marks, and you're measuring a wooden block, the measurement of the block should have two digits. So instead of writing 3 centimeters as the measurement, you would get more specific and write 3.0 centimeters. This brings us to significant digits.
If a measurement is recorded properly, all the certain digits and one estimated digit are called significant digits. There are 5 rules to significant digits.
1) All non-zero numbers are significant. (significant digits are underlined)
Ex. 3200
2) Sandwiched zeros are significant.
Ex. 0.405
3) Zeros that are only placeholders for a decimal are not significant.
Ex. .093

4) Zeros at the end of a number that also contains a decimal are significant.

Ex. 20.20

5) Exact numbers may be thought of as having an infinite number of significant digits.

Ex. 15

Significant zeroes and significant numbers are helpful because they relate to measuring. If you are measuring the mass of something, you want to get as specific as you can. If something weighs 154.3 grams, you don't want to record its measurement as 150 grams. That only has two significant digits. You want as many significant digits as possible. Everything we learned this week comes back to measurement and making work in Chemistry a little easier.