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-Kam

LAB 6-2B: Factors affecting reaction rate

Purpose: 

• To observe how various factors (temperature, surface area and the presence of a catalyst) affect the rate of chemical reactions.

Materials: 

Part 1 (Temperature):  

•  Two 400 ml beaker
•  Ice water
•  Hot water
•  Thermometer
•  3 Effervescent tablets (Denture cleaners)
•  Stopwatch

Part 2 (Catalyst): 

•  3 Small test tubes 
•  Test tube rack 
•  Dish soap
•  6% Hydrogen peroxide solution (H2O2)
•  Potassium iodide (KI) 
•  Copper(II) chloride (CuCl2)
•  Sodium chloride (NaCl)

Part 3 (Surface Area):

•  Mortar and pestle 
•  Sodium carbonate 
•  4 Small test tubes 
•  Test tube rack 
•  Dilute hydrochloric acid solution (HCL)

Procedure: 

•  Refer to page 279 of textbook

Results: 

Part 1 (Temperature):

	Hot Water	Cold Water	Warm Water
Temperature	57˚C	5˚C	27˚C
Approximate time it took to dissolve	After around 3 minutes about half of the effervescent tablet was dissolved, therefore we can estimate that it would have taken approximately 6 minutes for it to completely dissolve.	After around 8 minutes about half of the effervescent tablet was dissolved, therefore we can estimate that it would have taken approximately 16 minutes for it to completely dissolve.	After around 5 minutes about half of the effervescent tablet was dissolved, therefore we can estimate that it would have taken approximately 10 minutes for it to completely dissolve. I originally estimated around 11 minutes

Part 2 (Catalyst):

Fast	KI (Potassium iodide): This compound produced the most foam in the shortest period of time. The solution was yellowy orange in color. It eventually overflowed out of the tube. Thus it was the most reactive out of the three.
Medium	CuCl2 (Copper II chloride): This compound also produced foam although less than the potassium iodide it reacted fairly quickly. The solution was bluish green in color and the compound in the middle of the three.
Slow	NaCl (Sodium chloride): There was almost no foam and not a significantly visible reaction.  There was slight bubbling and fizzing. The solution was clear and the compound with the slowest reaction rate between the three.

Part 3 (Surface area): 

	Result:
Sodium sulphate lumps	Instantly fizzed but then settled, there were bubbles that continuously rose but then stopped anticlimactically.
Powdered sodium sulphate	Instantly fizzed but less dramatically than the lumps towards the beginning. Once stirred the reaction seemed to be faster compared to the lumps but then settled again towards the bottom.

Discussion:

Analyse

     1. What is the relationship between rate of reaction and change in temperature?

• The relationship between the rate of reaction and change in temperature is that the reaction rate will become faster if the temperature is higher and slower if the temperature is lower. This is due to kinetic molecular theory, if the temperature is higher the molecules move faster causing more collisions which results in a faster rate of reaction.

    2. Compare your prediction in step 4 of the length of time it would take an effervescent tablet to dissolve at middle temperature with how long it actually took.

• Through the results from the hot and cold water I predicted it to take around 11 or 12 minutes for the effervescent tablet in middle temperature water to completely dissolve. In reality during our experiment we estimated it to have taken around 10 minutes.

      3. 

       a) Which of the solutions that were added to the hydrogen peroxide solution may have acted as a catalyst?

• Because there was the same hydrogen peroxide and dish soap put in all three test tubes the only different factor among them were the solutions placed in to them which were all ionic. They all reacted although at different rates therefore they were all catalysts.

   b) Which catalyst sped up the reaction the most?

• Potassium Iodide was the catalyst which sped up the reaction the most.

     4. Which has more surface area, a 5g lump of sodium carbonate or 5g of sodium carbonate powder?

• We know that the 5g of sodium carbonate powder has more surface area because it is the same thing but crushed up therefore making more surface area and more surface for the molecules to hit as opposed to a lump where there is less surface area exposed.

     5. How did the surface area affect the rate of sodium carbonate 

decomposition in step 14?

• In this experiment at first the surface area didn't make much of a difference, in fact the lump reacted faster than the powder. However after we mixed the test tube containing the powder it reacted somewhat faster but it wasn't a drastic change. When surface area is increased, it allows for the dilute hydrochloric acid molecules to collide with more sodium carbonate atoms at a time, rather than only coming in contact with the atoms on the surface.

Conclude and Apply

     1. Suppose a reaction involved a finely ground powder reacting with a concentrated acid. Suggest three methods of decreasing the reaction rate.

• To decrease the reaction rate of a reaction involving a powder and a concentrated acid we could do multiple things. Firstly we could decrease the temperature of the acid causing the molecules within to slow down. Another way to decrease the reaction rate is to substitute the finely ground powder with a lump so that there is less surface area to react on and lastly we could refrain from using a catalyst which would slow down the reaction significantly.

Conclusion

• In conclusion through this experiment I was able to observe how temperature, surface area and the presence of a catalyst will significantly alter the rate of a reaction. I have now witnessed that the higher the temperature, the larger the surface area and the presence of a catalyst all contribute to a faster chemical reaction. Although all the experiments went well and we acquired accurate information we could have done part 3 in a better way to receive more prominent results. We should have used less powder and possibly even smaller lumps of sodium sulphate to make the results more obvious to the eye. All in all I really enjoyed this experiment and it has given me valuable knowledge that will help me aspire to my academically science-based future. 

LAB 5-1B: Properties of Acids and Bases

Purpose:

• The purpose of this lab was to determine how the properties of acids and bases can be used to classify solutions and to investigate the acid-base properties of four unknown solutions.

Materials:     

•   4x6 spot plate
•   Masking tape
•   Solutions A,B,C and D
•   4 pieces of Mg ribbon
•   4 pieces of red litmus paper
•   4 pieces of blue litmus paper
•   Bromothymol blue solution
•   Indigo carmine solution
•   Methyl orange solution

Procedure:

•   Refer to text, page 230

Results:

Mg Ribbon	Red Litmus	Blue Litmus	Bromothymol Blue	Indigo Carmine	Methyl Orange	Unknown
Bubbles	Pink	Pink	Yellow	Dark Blue	Red	A
No change	Blue	Light Blue	Blue	Green	Orange	B
Little bubbles	Pink	Light Blue	Turquoise	Dark Blue	Orange	C
No change	Red turned in to Blue	Blue	Blue	Dark Blue	Orange	D

Picture of results

Materials & Substances:

Left column to right column:

Mg ribbon – Bromothymol Blue
– Red Litmus – Blue Litmus – Indigo Carmine – Methyl Orange

Top row to bottom row:

Solution A – Solution B – Solution C – Solution D

Discussion:

Analyze

1. List the solutions in order from most acidic to least acidic (mostbasic).

• The solutions in order from most acidic to least acidic(most basic) are A, C, D, B.

2. Which solution do you think was neutral? Explain how you know.

• I think if there was indeed a solution that was neutral it would be Solution D because there were no bubbles in the solution with magnesium ribbon and both of the litmus paper color's changed the least out of all 4 solutions.

3. You used two bases. Explain how you know which solution was more alkaline(more basic).

• I know thatsolution B was more alkaline (more basic) than solution D because all the colorchanges were more extreme, especially the red litmus; it turned more bluecompared to solution D.

4. How can magnesium metal be used to distinguish between an acid and abase?

• Magnesium metal can be used to distinguish between anacid and a base because when you put it with an acid it produces hydrogen gas,which will produce visible bubbles in the solution.

Conclude and Apply

1.

(a) What color would each of the five indicators be in a solution thatis pH 3?

•     Red litmus – Red
•     Blue litmus – Pink
•     Bromothymol blue – Yellow
•     Indigo carmine – Dark blue
•     Methyl orange - Red

(b) What color would each of the five indicators be in a solution thatis pH 10?

•     Red litmus - Blue
•     Blue litmus – Blue
•     Bromothymol blue – Dark blue
•     Indigo carmine –  Green - Yellow
•     Methyl orange – Bright orange - yellow

2. Suppose you are asked to put together a test kit to determine whetherwater taken from a factory waste drain is acidic, basic, or neutral. Your kitcan contain only three tests. Which tests would your kit contain? Explain.

• If I could only have 3 tests I would put together atest kit containing Methyl orange, red litmus paper and Bromothymol blue. Thered litmus paper will clearly determine whether the solution is an acid or abase, if the result is closer towards the middle of the spectrum Bromothymolblue will narrow it down and determine if the water is slightly acidic or alittle more basic and Methyl orange will also help specify the pH level of thesolution towards the corrosive end and give a greater understanding andconfirmation.

3. Refer to the photo of the lichen Roccella tinctoria on this page,from which litmus is extracted. If this lichen were ground up and then soakedin vinegar, what color would the solution likely be? 

• If Roccella tinctoria was soaked in vinegar the solution would most likely be the color red because vinegar is acidic therefore it would have a low pH and be towards the red side of the spectrum. 

4. What is the color of seawater that has had Bromothymolblue added to it?

• The color of seawater with added Bromothymol bluewould be blue or towards the blue end of the spectrum because seawater is basic.

5. Consider the color-coded map of the world’s oceans shown to theright.

(a) Which regions of the world’s oceans appear to be most affected bythe drop in pH level?

• The regions of the world’s oceans that appear to bemost affected by the drop in pH levels are close to the poles of the earth, thenorth Atlantic towards Antarctica and the South Atlantic around the Arctic area.

 (b) Which regions are the leastaffected?

• The regions of the world that appear to be the leastaffected by the drop in pH level are the south side of the Pacific Ocean and asmaller region in the Indian Ocean.

Conclusion:

• Through this experiment I have gained a much greater understandingin how acids and bases react to different solutions, how we can use acids andbases to classify solutions and how much the pH level affects compounds andmany things around us. Through the clumsy solution pouring process thesubstances may have gotten contaminated, this is a factor that should be donemore carefully next time, possibly because of that factor some of the solutionswere hard to analyze therefore it was beneficial that we had various kinds ofindicators to confirm whether our observation of it being an acid or a base wasindeed correct. Another thing we could have done to improve our results is tosand our Magnesium ribbon to remove more oxides so that the bubbles are moreobvious to the eye.