Chem Blog Week 25

Over the weekend we were given the task to make an electroscope. An electroscope is a device that is able to measure the amount of charge an object has.

How to Make it

An electroscope model closely replicated to my final product

After going through different prototypes of electroscopes this is the process I found to work best. Crumple a piece of foil into a ball. Roll the smaller piece of foil between your palms to form a long, thin rod shape. Now connect the foil ball to the end of the rod with a thin strip of foil. Make a hole in the middle of the jar lid with a hole punch. Be sure that the hole is large enough for the foil rod to fit through. Slide the rod through the hole in the lid, so the ball sits above the lid, outside the jar, when the top is screwed on. Bend the bottom of the rod so it makes a 90-degree angle. The angle should resemble an uppercase L. Make a narrow strip of foil and fold it in the middle. Fold up each end of the strip to make small flaps. Hang the folded strip of foil on the end of the rod where you formed the L shape. The strip should hang evenly on both sides. Screw the lid tightly on the jar, with the foil rod and flaps inside.

How it Works

When a charged body is brought near the metal knob, both strips acquire a like. As a result, they repel each other and spread apart to form an inverted V. Each dangling sheet of the foil will now have a charge, the two dangling halves of the foil will now seek to repel each other as they have the same charge. The electroscope is then charged. If an oppositely charged body is brought close to the knob, the charge on the strips is neutralized, and they again hang straight down. The strips of foil hang straight down when they are not charged. The charge will transfer to the metal foil. The degree to which the foil flattens itself out is a measure of the amount of charge on the foil which shows the amount of charge on the original object.

 The day of the testing went great. I thought my electroscope stopped working but it was just because the object I was using was harder to charge than something like vinyl. There were different types made but they were all mostly based off the same idea. I did have some trouble actually making the electroscope. My original idea using copper wire didn’t work out because I couldn’t find any copper wire, and even the substitute of a wire hanger for the antennae did not give any results. I did some more research and found the best model to get the best results. This week was fun with our project and I hope that we have another project soon!









Chem Blog Week 24

This week, we learned more about charges and how they work on a molecular basis. A positive charge is one with more positive ions than negative ions. A negative charge is the opposite. And now we know what a neutral charge is. A neutral charge is one with an equal number of positive and negative ions.

We were shown an experiment including a sweater and a balloon on the SMART Board. The sweater and the balloon initially didn't attract each other because they had neutral charges. But, that changed when the balloon was rubbed against the wall, it became more positive while the wall became negative. The negative ion moves. I then wondered why the negative ions were moved rather than the positive ions. Did it have to do with the greater electrostatic strength of positive ions than negative ions? Or was it because the opposite charges of positive ions and negative ions held each other in place? It seems as if though this is the case because I think that the positive ions are stronger than the negative ions. It seems as if though the negative ions have less strength because they have a greater number of electrons than the positive ions. The reason I think this is so is because I think that the less electrons there are, the less pressure is being put on the "electro-chain" that holds the electrons in place. So in summary the charge of positive ions is stronger than that of negative ions.   

This same principle also applies to ionic compounds, which form when ions transfer electrons to form neutral compounds. Through the exchange of electrons one of the elements become positive while the other one becomes negative. This is what happens when NaCl combine. The Na needed to lose an electron while the Cl needed to gain one. So, through this "electron exchange", the Na became positive and the Cl became negative. They then formed an ionic compound, which means a neutral compound.

In order to find element’s charge you look at the periodic table and based off what column that element is you will be able to know its charge. This brought back a memory freshmen year in honors biology when our teacher gave us a rhyme to help us remember the charge of elements: “+1, +2,+3,+4, (transitional metals) -3,-2,-1, no more!” With this, I am easily able to find charges for the elements.

This week went pretty well. I believe I understand the concepts we learned this week. I just need to practice with some of the equations with the elements. We were also given the assignment to make an electroscope for Monday. I’ve seen some videos on how to make one and it seems simple to make. But I need to further understand how it actually works.

 

Chem Blog Week 23

This week, I learned about atomic charges through a class demonstration. When a classmate rubbed the pen on his shirt, he then held it up to the match and the match moved–without any physical contact. I knew that the reason was because charge but I did not know how charges work a particle level. The first thing I learned was that a charge involves static electricity. We found that this from the flow of Electrons. Electrons are the smallest possible piece of an atom. This means that something is smaller than the atom. The exchange of electrons allowed the pen to have moved the paper clip without touching it. Because we now know that there is something smaller than the atom we have to change the way we draw particle diagrams to represent them at the smallest level. Particle diagrams in the past units could still be drawn the same using dots to represent particles.

Charges occur when the electrons transfer from one place to another. Depending on the charges, they could charge with other things. This is what I learned in the sticky tape lab. In this lab, we tested two pieces of tape: one tape taped onto another tape. The objective was to test the top tape and the bottom tape with other things to determine whether they would repel or attract. The top tape that was ripped off the bottom tape seemed to attract to the bottom tape. Next, the bottom tape was tested with the paper and the aluminum. The bottom tape attracted to the aluminum, but repelled the glass rod. Hence, the aluminum must be positive while the glass rod was negative. Through this example, I learned that opposite charges attract while the same charges repell

ed like a magnet would. This is because if the bottom tape and the top tape attracted together, they have opposite charges because when the top tape was ripped from the bottom tape, the top tape became positive while the bottom tape became negative. So, if the top tape is positive, then it would attract to something negative like the glass.

We also tested the conductivity of certain materials, like brass, silver, iron, zinc, copper, plastic, cardboard, and glass. The equipment we used included two battery sets, wire clips, and a light bulb. We found all the metal products were connected to the wires, the batteries, and the light bulb, the light bulb lit because the electrons flowed through the wires to the light bulb. The nonmetal products, however, did not conduct electricity because the light bulb did not light up.

Like I said in my last blog, this week was full of new things! I understand everything and it was easy to learn. We even had 3 experiments this week! I don’t know how next week will top it!

Chem Blog Week 22

This week, I learned more about the complexities of finding the number of moles. Also this week we had the MME/ACT testing so I was not in class for most of the week so this blog will be a short one. We practiced more with mole calculations and the concept and the mole but I am still a little shaky with how to find the number of particles or the number of moles or the mass.  It probably showed on the assessment we took online. I can describe what the mole represents and how it works in writing but the calculations mess me up. I am also able to find molar mass with the periodic table. This both connects with the electrolysis lab from last week and the things we learned earlier. Hopefully I will be ready before the reassessment because I tutor in chemistry and if I don’t have a grasp on the concept, neither will the person I tutor. I will ask my friends for some help about it.

Because this week was the ACT’s I will talk more about that than anything. I felt as if I was too calm compared to other people but I feel I did alright overall. I struggled on the science but I saw comfort that others also had some trouble with that subject as well. Even though my strongest subject is science. But it’s not really about your knowledge of science but your ability to understand graphs and charts and given information that was given. I’ll try to find something that would help me improve my test taking strategies. The other tests went well and the test went by quickly but when it was over I was exhausted!

Next week I am guessing that since we did not get to do much this week next week will be twice as busy. But I am okay it!

Chem Blog Week 21

This week in chemistry we learned the connection between molar mass and density that if you know molar mass you are able to determine the density of the the element. In the case of our electrolysis experiment, hydrogen and oxygen.

This week, my group and I did an electrolysis experiment. I was so excited because ever since we saw the process of electrolysis on the SMARTBoard I wanted to try it out for myself. We had to hook up two probes to two metals ends at the bottom of the trough. We had to fill the trough with sodium chloride water solution. But, why not water? This is the part I felt I wasn't so sure of, but I think it had to do with the fact that sodium chloride could conduct electricity in order for the hydrogen and oxygen particles to chemically split from each other.

Then we use two graduated cylinders (one for hydrogen and the other for oxygen) and put them on top of the metal ends making sure that they are still full. This was a little hard but we were able to do so in a few attempts .This reminded me of the experiment a while ago with the trough but I think this was a bit simpler because instead we had to scoop the tubes with the solution and slowly tilt them to the bottom of the trough, then tilt it again toward the metal end and cover it with the tube without going over the top of the tube. It felt like doing brain surgery with the amount of caution to flip over a test tube!

Then, after that ordeal was over with, we then cranked the machine and repeatedly turned the handle clockwise. We then kept track of the volumes for each of the tubes filled with the hydrogen and oxygen. Every time we recorded the data, there was twice as much volume of the hydrogen as there was oxygen.

We ended up finding out that compared to hydrogen oxygen is much denser even though hydrogen has twice as much volume. This adds up because we now know that the molar mass of oxygen is 16 g/mol and that hydrogen is only 1 g/mol.

This week was very fun because we did a group lab and that is one of my favorite aspects of chemistry and science in general: the experiments! With this experiment I was able to get a greater grasp of molar mass and of the fixed ratio of compounds. Feel confident with the concepts of this week hopefully I do this well next week. I am not sure what is to come next week but I trust that I won’t be disappointed with what I learn next!