Chemthink Questions

1. The starting materials in a chemical reaction are the Reactants
2. The ending materials in a chemical reaction are the Products
3. The arrow indicates a Reaction has taken place
4. All reactions have one thing in common: there is a rearrangement of chemical bonds
5. Chemical reactions all involve breaking old bonds and forming new bonds, or both.
6. In all the reactions we still have all of the atoms at the end that we had at the start.
7. In every reaction  there can never be any missing or new atoms when the reaction is over
8. Chemical reactions only rearrange bonds in the atoms that are already there.
9. 2H2+O2--->2H2O
10. 2h2 + 2O2 = 4H2O
11. The idea is called Law of Conservation of Mass
12. There must be the same atoms and the same number of mass before the reaction (in the reactants) and after the reaction (in the products).
13. 2Cu + O2 = 2CuO
14. Reactants: Cu: 1 O: 2 Products: Cu: 1 O: 1
15. To balance this equation, we have to add CuO molecules to the products because this reaction doesn't make lone  atoms
16. When we added a molecule of CuO, now the number of O2 atoms is balanced but the number of Cu atoms doesn't match. Now we have to add a Cu atom.
17. 2Cu + 1O2 ---> 2CuO
18. 2CH4 + 3O2---> 2H2O + 2CO2
19. N2 + 3H2---> 2NH3
20. 2KClO3---> 2KCl + 3O2
21. 4Al + 3O2---> 2Al2O3

1) Chemical reactions always involve breaking bonds, making bonds, or both.
2) The Law of Conservation of Mass says that the same atoms must be present before and after the reaction.
3) To balance a chemical equation, you change the coefficients in front of each substance
until there are the same number of each type of atoms in both reactants and products

We did four experiments. Each one had a different result and a different chemical reaction. The first one we did was ethanol + oxygen + fire = carbon dioxide + water. Ethanol was in a 2 liter bottle and was shaken until it became a gas. The cap was removed from the bottle and the tip of the bottle was next to an open flame. The oxygen mixed with the ethanol. The ethanol, oxygen mixture caused the bottle to shoot backwards and increase the size of the flame. As a  product of this, carbon dioxide and water were made. I thought the bottle would implode from the pressure, but instead it shot backwards. This kind of reaction was combustion. It was combustion because fire was used to get the products water and carbon dioxide.

In the second one, baking soda and vinegar was poured into a beaker and carbon dioxide was formed. A candle was placed on the cart and the CO2, being heavier than air, poured out onto the candle. The carbon dioxide replaced the oxygen around the flame on the candle, eliminating one of the three essentials of fire-oxygen. It put out the flame because the CO2 replaced the oxygen. That is what I thought was going to happen so my hypothesis was correct. The chemical reaction in this one was acid and base because vinegar was an acid (the ph level was high) and the baking soda was a base because the ph level was lower.

In the third one, zinc was added to hydrochloric acid. My thoughts were that it would bubble up and produce large amounts of gas in the beaker it was in. The zinc did bubble up and because of that, the water turned green. After it kept bubbling for a few seconds, a flame was introduced, it sped up the process. The zinc bubbled faster and the flames only stayed on the top layer of the hydrochloric acid. Steam was also produced making it single displacement because the zinc combined with the chlorine and went away from the hydrogen.

In the fourth experiment hydrogen peroxide was added to potassium iodide. When dish soap was also added, a big tightly packed foam formed and spilled out of the container. Before the experiment started, I thought that something slimy and foamy would form and spill out of the container. The hydrogen peroxide and potassium iodide created gas and the dish soap trapped the gas in it. That is why the foam was created. The chemical reaction taking place was decomposition because in the chemical equation, H2O2 was broken down into H2O and O2.

100 Greatest Chemistry Discoveries

100 Greatest Discoveries:

A Greek Philosopher discovered the first 4 main elements: earth, water, fire, and the primary air. Priestly (very well known for science) discovered mercury and created the first technology to contain a controlled amount of liquids and gasses that could be heated at a set temperature. He created and discovered many different elements including oxygen. A man named Jon Dalton, showed how elements combined in different proportion change and made up the word atomic weight. Joseph Lusoc then saw how mixed gasses produced twice the volume (when mixed) of the original gasses. Avogadro said that gas was made of many different molecules instead of just one substance. Vowler created inorganic urea on accident and Kekulai developed new ways to show bonds between molecules. Mendeley found 63 different elements and constructed cards to show their properties. He saw a pattern and eventually created the periodic table. Davy was the one who found out that compounds are made of several elements and when electricity is added to them, it can create new elements. This was called electrochemistry, and it led to aluminum, semiconductors, solar panels, LED displays, and rechargeable Li batteries. Robert Bunsen and Gustav Kerchief saw how elements put into fire changed the color of the flame. With this and the observation of light in a prism, he invented the first spectroscope. Today, the spectroscope is used to search for water and life on other planets from earth. Joseph Thompson discovered the electron while he was a professor at England Cambridge. He also realized that some atoms were radiant because of the electron configuration. Gilbert Louis developed the first model of an atom and saw how atoms can give up and accept electrons from other valence electrons of other atoms. On top of that, he found out how to create compounds. Shortly after him, Rebeck Rell tried to see which minerals emitted radiation. His technique was to put the mineral on unexposed photogenic plate. He did that with uranium and found it was the most radiant element out there. Marie and Pierre Curie continued on that idea and tried to isolate the elements responsible for radioactivity in uranium. She found that it was radium and it was a million times more radioactive than uranium. Later, man found out that there were many benefits from radioactive things in all areas of life. Shortly after they died from radiation poisoning, Jon Hyett created plastic which was essentially a way to exploit cellulose. Leo Baekeland discovered the first synthetic plastic and found that plastic was a polymer which is a chain of molecules. Carbon nanotubes were then found by Robert Kerl. He was looking for what interstellar matter was made of and in the process found this. They were only made of 60 atoms, no more, no less. It was also 100 times stronger than steel.

Dissolving of Alka-Seltzer

Title: Temperature and the Dissolving of Alka-Seltzer

State the Problem: How will temperature affect the speed at which the Antacid tablet dissolves?

Hypothesis:  If the temperature goes up, then the antacid tablet will dissolve faster because there will be more room for the antacid molecules to go in the water because the water molecules will have more room in between then from the heat.

If the temperature goes down, then the tablet will dissolve slower because there will be less room for the tablet molecules to go in the water because the water molecules will have less room in between them from the lack of heat.

Materials:

• 500 ml beaker
• graduated cylinder
• Vernier temperature probe
• Computer
• Logger pro software
• Vernier computer interface
• 4 alka-seltzer tablets, stopwatch, hot plate, 5 ice cubes

Procedures:

For the hot water test, you must first fill a beaker with 266 ml of water. Then place the temp probe inside beaker on hot plate, and heat on high until 50ºC. Use the stopwatch to record the amount of time it takes to dissolve. Use the probe to take the temp and record it on the computer by clicking run once the tablet is in the water and clicking stop when it is done dissolving. Also record the temperature and the time in your lab notebook.

For the room temp test, you must first fill a beaker with 266 ml of room temp water and put the probe inside the beaker. Drop one tablet into it and click start. Use the stopwatch to record the amount of time it takes to dissolve. Once it is done dissolving, click stop and the software will have recorded the time and temp. Also record the temp and time in your lab notebook

For the cold water test, you must first fill a beaker with 133ml of water and put 5 ice cubes in it. Stir the ice water for about 30 seconds so the temp evens out. Put the probe in the water and drop the antacid tablet in. Use the stopwatch to record the amount of time it takes to dissolve. Click run and once the tablet is done dissolving, click stop. Record it in your lab notebook. The computer will do it automatically.

For the boiling water test, you must first fill a beaker with 266 ml of water and put it on a hotplate. Put the probe in and wait till it is at 100ºC. Use the stopwatch to record the amount of time it takes to dissolve. Drop the tablet in and click start. Once it is done dissolving click stop. Record the information in your lab notebook.

Data and Analysis:

This picture is showing the logger pro system recording the data for the hot water test. At this moment, the water was at about 100 degrees and getting ready to start cooling.

This picture is showing the logger pro system recording the data for the cold water test. At this moment, the water was at about 4 degrees over a 100 second time span.

This picture is showing the logger pro system recording the data for the room. At this moment, the water was at about 21 degrees.

1.This is the room temperature water and shows that it took almost 50 seconds to dissolve in about 22ºC.

2.This is the cold water and it shows that it took a much longer time to dissolve at a colder temperature. Almost 1 minute 50 seconds. That is much longer than the ones with higher temperatuers

3.This is the graph with the hot water. It was heated to about 50ºC and it took the shortest time for the antacid tablet to dissolve.

4.The boiling water was at about 98ºC and took about 22 seconds to dissolve. It weird because it took longer here than the hot water and this one was hotter.


Conclusion:

The hypothesis was proven correct because it did take a longer time for the tablet to

dissolve in the cold water than the warmer ones. Each time the temperature went up, it took a less amount of time for the tablet to dissolve, except for the boiling water. It took longer for it to dissolve than the hot water even though it was hotter...at least twice as hot. The first 3 tests supported my hypothesis but the boiling water did not and I do not know why. The only variable was the temperature, so we know that my hypothesis was correct because the temperature changed the dissolving time.

Glue and Borax Lab

Title: Cross Linking Elmers glue with Sodium Borate

Problem: How is a polymer formed by using glue and sodium borate?

Hypothesis:  If the glue and borax and water is mixed together, the molecules will combine into a chain making it stick to itself, feel rubber, and bounce because when the molecules form a chain, it makes it a polymer and polymers have those properties.

Materials:

• 500mL Water
• 25mL Elmer's glue
• 1 Tablespoon
• 1 tsp. Borax
• 1 graduated cylinder
• 1 600mL Beaker
• 1 250mL Beaker
• Stirring rod

Procedures:

Fill the 600mL Beaker with 100mL of water. Then add one tablespoon (about 3 teaspoons)  of borax powder. Stir until the borax is completely dissolved. the borax did not completely dissolve in ours. Measure out 25 mL of Elmer's glue into the 250mL beaker. Add 5ml of water and gently stir. the glue solution did not get thicker, but a little bit thinner. Mix 40mL of the borax solution to the glue solution. Stir vigorously and watch the new solution change in texture and appearance. Our new solution very thick and looked creamy.  Take out the polymer and dump out the extra runny liquid. At first, ours was very wet, but as we performed the tests, it dried. Also, it was very slimy. The polymer had a faint glue smell to it.After this there are test that can be performed. The first test done was the slime rating. 5=very slimy, and 1=not slimy. Our slime/polymer was about a 2 or 3. The next test was the slow poke test. Roll the polymer into a ball and slowly poke your finger into the polymer. After that we did the quick poke test. Roll the polymer into a ball and quickly poke your finger into the polymer. Next was the slow pull test. Slowly pull apart the polymer. After that test was the quick pull test, the bounce test, and the blob test.  

Observation / Results:
slow poke- Finger is pushed into the slime, it wasn't super easy and it required some force.
quick poke- Finger does not go into the goop, finger goes to one side and the goop to the other.
slow pull-Expands, can pull apart like a spring but only went back together after some pressure
quick pull- Comes apart easily and quickly
bounce- 10 centimeters (small blob bounces higher, big blob bounced lower)

This image shows the glue  and borax before it is mixed.

This images shows the glue and borax forming the polymer as it is mixed because they clong together.


Analysis:
1) How is slime visco-elastic?
Our slime was visco-elastic because when being formed, it was thick,  and had a sticky consistency. It could be stretched like elastic.

2) What are the physical properties that change as a result of the addition of sodium borate to the Elmer's glue?
When the borax solution was added, the glue solution got thicker and became more solid.

3) What would be the effect of adding more sodium borate to your cup(your thoughts only)?
I think that adding more sodium borate to the glue solution might make more slime, and the process of changing from a liquid to a solid might go faster. There might not be as much liquid left.  

4) After making the observations on the dried glue, how does the water affect the elasticity of the polymer? What is elasticity?  
Elasticity is basically how stretchy something is. The technical definition is the tendency of a body to return to it's original shape after being stretched or compressed. If there is more water,then the elasticity is usually higher. If there is too much water, there is too much extra liquid left over.

5) Find and circle the repeating unit in the polymer below.  
The repeating unit is vinyl alcohol.


6)What is the structural formula of the poly(vinyl alcohol) monomer circled above?
CH2CHOH

7) In the picture below, circle the borax cross linking agent.


Conclusion: The solutions did mix and turned into a polymer after the water was gone, so my hypothesis was proven correct. It did bounce and had a very rubbery texture. It also stuck to itself very well and was hard like a big piece of rubber. It was not very stretchy when it was dry, but it was when there was a lot of water in it. There were not any errors in this experiment and my hypothesis was completely correct. To modify this experiment, maybe we could have observed the polymer under different temperatures.

Sodium Polymer Lab

Title: Sodium Polymer Lab

Problem: How will sodium silicate affect the strength of the polymer?

Hypothesis: If sodium silicate is added to the ethyl alcohol, then the polymer will be stronger because the water is being taken out and replaced by the ethyl alcohol.

Materials:

• Sodium Silicate 12 mL
• ethyl alcohol 3 mL
• 2 small beakers
• stirring rod
• paper towels

Procedures: First, we poured the 2 solutions together and mixed it up until it was very chunky. After that, we started to mold it into a sphere. We had to wet it a little bit to mold it because it was not easily molded but with a little water and pressure, it became easier. After we made it into a sphere, we did some tests and it did bounce and when the water dried out, we had to wet it again because it would start to crumble, so the water held the 2 solutions together.

Data and Analysis:
1. It is clear and clumpy. When you squeeze it together, it forms one piece and you can mold it.
2. They are both moldable and have properties that make it bounce.
3.They are both moldable, bouncy, and hold their shape.
4. There was a reaction because a solid formed when the mixed together.
5. The water makes it moldable, and when squeezed, it comes out and since there is no water
left, it becomes non moldable and it crumbles.
6. Ours was the biggest and most spherical. Other people didn't have a good sphere, but it still bounced. Theirs did not bounce as high as ours and their diameter was smaller.
This was the polymer while it was being mixed. The water was still in it and that is why it is all together. It started crumbling after we took it out because the water started to dry up. At this point, it felt like dry deodorant.
This is what it looked like after we added a little more water and started to mold it into a sphere. It wasn't completely done and it broke easily because there was too much water in it. It was white and and had swirls in it, so it almost looked like a marble.
This was the finished product. It was bouncy, shiny and looked like a marble very much. It was large because we used all of the product that we made. We rolled and squished it into a sphere, so it was just like a bouncy ball. Occasionally, we had to add a little bit of water to it to keep it from drying out and crumbling.

Conclusion: My hypothesis was proven correct because the polymer did become stronger when there was less water in it. The water held the 2 solutions together very well and that is why they stayed combined and the water gave it all the properties of sticking together, being bouncy, and being moldable. It was just like the other polymer that we made before, except it looked and felt a little different. The other one felt rubbery while this one felt like dried deodorant when water was added to it. When it was in a sphere though, it felt smooth and just a little sticky. A way we could modify it is by testing the properties of it at different

Temperature and Solubility

Title: Effect of Temperature on Solubility of a Salt

Problem: How does temperature affect the crystallization of KNO3?

Introduction:

In the lab, the independent variable is the potassium nitrate. The salt (KNO3) is put in every test tube, and different amounts are put into each one. The solubility of salt in the water is being affected by the temperature. The higher the temperature the more energy there is in the water, this makes it easier for the potassium nitrate to break apart and dissolve into the water. The effects of the temperature on solubility is important because when making scientific solutions, it is important to know what you need to use when making them.

Hypothesis:
If the temperature rises, the KNO3 will dissolve faster because of more energy in the container provided by the heat.

Materials:

• Computer
• Vernier computer interface
• Logger Pro
• Temperature Probe
• 2 Utility Clamps
• Four 20 times 150 mm-test tubes
• Test tube rack
• Ring Stand
• Hot Plate
• Stirring rod
• Potassium Nitrate (KNO3)
• Distilled water
• 400 mL beaker
• 10 mL graduated cylinder or pipet
• 250 mL beaker

Procedure:

Get and wear goggles. Label each test tube 1-4. In the test tube labeled 1, put 2 ml KNO3. In the test tube labeled 2, put 4 ml KNO3. In the test tube labeled 3, put 6 ml KNO3. In the test tube labeled 4, put 8 ml of KNO3. Add 5 ml distilled water to each one. Open the Logger Pro software and connect the Vernier computer interface to the computer. In channel 1, attach the temperature probe. Fill a 400 mL beaker three-fourths full of tap water. Place it on a hot plate situated on (or next to) the base of a ring stand. Heat the water bath to about 90°C and adjust the heat to maintain the water at this temperature. Place the Temperature Probe in the water bath to monitor the temperature and to warm the probe. Use the utility clamp to fasten one of the test tubes to the ring stand. Lower the test tube into the water. To dissolve all of the KNO3, Test Tubes 3 and 4 need to be heated to 95º C than Test Tubes 1 and 2. Use the stirring rod to stir the mixture until the KNO3 is completely dissolved. Don’t leave the test tube in the water bath any longer than is necessary to dissolve the solid. When the KNO3 is dissolved click the collect button and put the temperature probe into the test tube. Bob the probe up and down in the tube while waiting for crystals to form. Once crystals start to form, click keep. Put the solubility value in the edit box and press the enter key. After the data pair has been saved, return the test tube to the test tube rack and place the Temperature Probe in the water bath for the next trial. Repeat the same steps with the other 3 test tubes. When the data is finished collecting, click stop . Record the temperature (in °C) from the four trials in the data table.

Data and Analysis:
The water in the third and second test tube cooled causing the solubility to rise. The hot water dissolved the salt because the molecules separated and there was room for the salt particles, but when it cooled, there was no longer any room since the molecules pul ed together, so the solubility had to rise since the molecules were forced to crystalize. The first and second solubility rose with higher temperatures because there was more room for the molecules to stay dissolved when they were cooled. At 110g of KNO3 in 100g water at 27.7ºC , it would be unsaturated. At 60g of KNO3 in 100g water at  35.8ºC, it would be saturated. At 140g of KNO3 in 200g water at 76ºC, it would be saturated. Yes because the small amount of solute has room to dissolve in the 50ºC of water since the molecules will be separated a pretty good deal.
No because that much of solute does not have room to dissolve with the other molecules still that close together because of the temperature. I would say about 15 g of solute because the molecules wouldn’t make enough room for anymore salt than 15 g. Also, because 40 g of solute was used in 90ºC water, so since it is about cutting the degree in half, the amount of solute would be to.

Test Tube Number	Amount of KNO3 used per 5 mL H20	Amount of KNO3 used per 100 g H20
1	2.0	40
2	4.0	80
3	6.0	120
4	8.0	160

Original Graph taken from Logger Pro:
Graph we had to make do to the error:
Lab setup:



Beaker setup:

Trial	Solubility (g / 100 g H₂0)	Temp (℃)
1	40.0	24.7
2	80.0	35.8
3	120.0	76
4	160.0	84

Conclusion:

In the end, my hypothesis was wrong. As it was colder, it was more soluble as shown in Graph 1. There are changes that could have been made like adding more KNO3 or adding more water. If you added more KNO3, I think it would take a colder temperature to dissolve it. If you added water, there would be no telling what could happen after seeing the data.  You could also use other element combinations to see other reactions. Those different changes could discover something completely new. We did have a couple of errors during our experiment. For instance, when we were graphing our data and we stopped recording, we hit the keep button which messed with the chart. It graphed the data in the wrong areas as shown in our first graph where the shape is rhombus. If we didn’t catch this our data would have been thrown off. Due to this mistake, we had to make our own chart with what we had as the right data and when you do this it is risky because you could put the wrong data in. Another error in our data is that when we were doing each test, we needed the starting temperature to be at 90 degrees but sometimes we could not get the temp to stay at exactly 90 which will also cause a difference in our data.