Chemical Reactions

Observations During the Experiment

• When we mixed the salt to the water we noticed that there was a decrease in the temperature of the mixture.
• The mass of the iron and water that was used before the experiment was 50g.
• A red colored substance has formed around the iron.
• As the red colored substance formed there a sight temperature increase where it formed on the iron.
• The red colored substance is very brittle and can be scratched off with sand paper.
• The mass of the iron and the red colored substance, when the experiment was finished is 50g.

     Iron with 20% saltwater

Nathan and Marta are doing an experiment to determine the effect of different types of water on the rusting of iron. They decide to use tap water, a 10% water solution, and a 20% saltwater solution. In order to make the saltwater solution they must dissolve salt into the water. They added a piece of iron to each of the mater mixtures for one week and made sure the system was closed so that no water could escape. They didn't add anything else to the iron. The picture above is how they found the iron that was treated with the 20% saltwater solution. Observations that were made during the experiment are listed to the right of the picture

 

1. Where did a physical change occur and where did a chemical charge occur? Explain how you know.

 

2. Identify where an exothermic reaction and an endothermic reaction occurred. Explain how you know.

Hi experts,

I designed an experiment to test the effect of increasing the saltconcentrations on the corrosion rate of iron nail. I had thecontrol (no salt), 0.63%, 6.3%, 14.5% and 29% (% mass/mass). After2 weeks when I got the nails out and wiped all of them with papertowel, I found that there is a black substance sticking on thenails immersed in the 0.63% and 6.3%, where in 6.3% salt solution,the black was the most. After the 3rd week, the 6.3% had less thanthe 0.63%. Note that in the 14.5 % and 29 %, no black substance wassticking. I found that as the salt concentrations increase, thereis more red rust.

My question is:

1) Why is less salt causing more black substance sticking? when Iresearched on the Internet, I found that the black substance wasmost likely to be FeO (as it is sticky) and they say that it formsin anaerobic conditions and that red rust (Fe2O3) forms when oxygenavailability is more and I also found that more salt decrease theoxygen solubility. If this is so, shouldn't the least saltconcentrations have the least black rust and the most red rust asthere is the maximum amount of Oxygen? (i.e. black forms inanaerobic or when oxygen amounts are little and red forms whenthere is more oxygen).

Please help me, I have to find trends in my data and explain themin details. Any help will be appreciated.

Thank you in advance
Best Regards

I am doing an experiment on saponification. we conducted a hard water test at the end with 4 different test tubes. this experiment went as follows

"Hard Water Reactions.

Place about one-third spatula full of the soap you have prepared in a 50-mL beaker containing 25 mL of water.

Warm the beaker with its contents to dissolve the soap.

Pour 5 mL of the soap solution into each of 5 test tubes (nos. 1, 2, 3, 4, and 5).

Test no. 1 with 2 drops of a 5% solution of calcium chloride (5% CaCl2), no. 2

with 2 drops of a 5% solution of magnesium chloride (5% MgCl2), no. 3 with 2 drops of a 5% solution of iron(III) chloride (5% FeCl3), and no. 4 with tap water. The no. 5 tube will be used for a basicity test, which will be performed later.

Record your observations on the Report Sheet. "

OUR RESULTS ARE AS FOLLOWS

test tube #4 (water) : Solution turned an thick orange color, no transparency

Test tube #3 (iron III chloride): Solution turned an thick orange color, no transparency

test tube #2 (magnesium chloride): Solution turned an extremely cloudy color, no transparency

test tube #1 (calcium chloride): Solution turned a cloudy white color, solid particle was formed in the middle along with a few bubbles on the top

my question is, what do the results for each test tube mean? i am having trouble writing up my discussion. the full lab link is as follows: http://www.seattlecentral.edu/faculty/ptran/bastyr/Summer%2006/organic/Organic%20Exp/Experiment4Preparation%20and%20properties%20of%20a%20soap1.pdf

Part 1: Separation of Iron filings

1. Mass a watchglass and record
2. Obtain a Kimwipe tissue from the top of the benches and a rodmagnet
3. Wrap the Kimwipe tissue around the magnetic end, holding thetissue tight to the rod magnet.
4. Swirl the Kimwipe in your mixture. Knock off excess sand beforemoving on to step 5
5. Carefully over the watch glass remove the Kimwipe tissue fromthe magnet so the iron falls on the the watch glass
6. Repeat steps 4 and 5 two more times, make sure you record howsuccessful this separation was � does the evaporating dish containonly iron?
7. Mass the watchglass and the collected iron.
8. Dispose of the iron in the hood.

Part 2: Separation of N

1. Mass a clean, dry, evaporating dish.
2. Pour the leftover mixture from step 1 into the evaporating dishand mass.
3. Place the evaporating dish on a hot plate in the hood.
4. Gently and slowly heat the mixture until the white fumes cease.Be patient. Depending on the amount of ammonium chloride in yoursample, this could take quite a while. A half our would not beunheard of.
5. Stir the mixture frequently to facilitate the sublimation ofthe ammonium chloride. This is crucial in order to obtain goodresults. (Use crucible tongs to hold onto the dish so it doesn�tmove as much)
6. After the white fumes disappear, turn off the hot plate andremove the evaporating dish with crucible tongs and let it cool inthe hood.
7. When the evaporating dish is cooled, mass the left overmaterial and the evaporating dish.

Part 3: Determining the amount of NaCl.

1. Measure 10 mL of distilled water in a graduated cylinder.Slowly add the water to the mixture in the evaporating dish whilecontinuously stirring with a clean, glass stirring rod. Afteradding all of the water, stir for 2 min more.
2. Assemble the gravity filtration apparatus shown in Figure1.
3. Fold a piece of filter paper as shown in Figure 2. Open up thepaper cone, and place it in the filtering funnel.

1. Position a beaker under the funnel, making sure that the funnelstem is touching the inside wall of the beaker. Pour as much of thesupernatant liquid as possible from the evaporating dish intofunnel. Collect the filtrate in the beaker.
2. Transfer the solid remaining in the evaporating dish into thefunnel, using a stream of distilled water from a wash bottle, asshown in Figure 3.
3. Re mass the watchglass from Part 1 and record this mass.
4. Pour the filtrate in the beaker into the evaporating dish
5. Place the evaporating dish containing the filtrate on a hotplate. Begin heating the solution.
6. While the solution is heating to boiling, move onto Part 4

1. Carefully remove the filter paper and residue from the funnel.Place the paper and residue onto the watchglass.
2. Place the watchglass with the filter paper and sand on top ofthe boiling salt solution to dry the sand
3. Keep the salt water boiling, until there is just a little bitof water left, or popping sounds are heard, then turn off the hotplate, and allow the heat from the hot plate to finish evaporatingand drying your salt.
4. Allow the evaporating dish and its contents to cool to roomtemperature.
5. Obtain another watch glass and mass.
6. Transfer the dried sand and filter paper from original watchglass (caution, salt has spattered onto this watch glass, so don�tknock any off, that is product you will need) onto the new cleanmassed watch glass. Replace the original watch glass onto thecooling evaporation dish
7. Mass the new watch glass, sand and filter paper all together.Discard filter paper and sand into garbage. Observe how pure yoursand looks.
8. After evaporating dish has cooled, determine the mass of theevaporating dish, watch glass plus NaCl. Record this mass. Then,discard the NaCl as directed. Wash evaporating dish and watch glassto dissolve the salt.
9. Observe how pure your salt looks.

Result and Discussion: Separation Lab

Overall percentRecovery:

A) Explain what steps(s) youcould have improved (and how) to help your percentrecovery.

b) Write a paragraph about thelab include briefly what was done, your result, were you correctand possible experimental errors- do not state human measurementerrors as errors. Be Specific, what specific human errors occurred,what measurement errors occurred, what process in the experimentcould errors have occurred.