6-2B Lab: Factors affecting Reaction Rate

Lab 6-2B: Factors Affecting Reaction Rate

Purpose:

The purpose of this lab was to explore the different factors that can have an affect on reaction rate. The factors investigated were temperature, surface area and presence of a catalyst.

Materials:

Part 1

·        Two 400 ml beakers

·        Ice water

·        Hot water

·        Thermometer

·        3 effervescent (carbon)

·        Stopwatch

Part 2

·        3 small test tubes

·        Test tube rack

·        Dish soap

·        6% hydrogen peroxide solution (H₂O₂)

·        Potassium iodine (KI)

·        Copper(II) chloride (CuCl₂)

·        Sodium chloride (NaCl)

Part 3

·        Mortar and pestle

·        Sodium carbonate

·        4 small test tubes

·        Test tube rack

·        Dilute hydrochloric acid solution (HCl)

General Procedure (refer to page 278-279 in the textbook)

1. Part 1: Effect of temperature
2. Effect of adding a catalyst
3. Part 3: Effect of surface area

Results

Part 1:

Hot water 

Cold water

Temperature	Time for effervescent tablet to dissolve	Extra Observations
4 degrees Celsius	5:55 minutes (limit) -it was half way dissolved but stopped reacting so for it to have fully dissolved would have taken over 13 minutes	-Little froth -slow bubbles -very pale blue	Cold water
48 degrees Celsius	3:15 minutes	-immediate reaction -lots of froth -lots of bubbles -brighter blue liquid	Hot water
26 degrees Celsius	Prediction: 10 minutes Actual time: 10-11 minutes (stopped at 5 min and it was halfway dissolved)	-froth -bubbles -pale blue liquid	Combined water

Part 2

Temperature	Observations
4 degrees Celsius	-Turned an orange yellow colour fast -Lots of froth (almost overflowed) -Took a second then froth “dramatically” increased in height	Potassium Iodide
48 degrees Celsius	-turned blue fairly fast -some froth and bubbles	Sodium Chloride
26 degrees Celsius	-Stayed clear/slightly pink -no froth	Copper Chloride

Part 3

(crushed sodium carbonate on left, solid  on right side)

·        Crushed sodium carbonate reacted faster (when placed into hydrochloric acid)

·        Solid sodium carbonate reacted slower (when placed into hydrochloric acid)

Analyze

1. The rate of reaction between changes in temperature is as follows: the higher the temperature the faster the reaction rate, the slower the temperature the slower the reaction rate. This effect can be explained through kinetic molecular theory in which when heat is added particles start to move faster, more energy is created and particles are more likely to bump into each other with harder collisions.  
2. My partner, Celina and I predicted for the tablet to dissolve in roughly 10 minutes in combined temperature water. We took the average of the time it took for the tablet to dissolve both in hot and cold water and adding on an extra 2 minutes (reasoning that 8 minutes seemed too quick). Our prediction was proved correct because after 5 minutes of observation the tablet was ½ dissolved.  Using basic arithmetic we can concluded that the tablet would completely dissolve in roughly another 5 minutes (give or take).
3. (a) The two solutions that could have acted as catalysts were Potassium Iodide and Sodium Chloride. Both they solutions showed an almost immediate reaction when added into the soap and 6 percent hydrogen peroxide solution; they changed the colour of the solution and started to froth and create bubbles.

(b)  Potassium Iodide sped up the reaction the most making me conclude that it was the best overall catalyst.  With only a small piece of solid the solution immediately started to froth, change colour and almost overflowed from the beaker.  

4.      A 5g of sodium carbonate powder has more surface area than 5g lump of sodium. Although they both have the same mass  the powder exposes surface area on each little “piece” that composes the mass   while the lump only exposes the surface area of the top of each particle while hiding inside the surface area of the other particles that compose it

5.      The more surface area exposed the more surface area is exposed to molecules therefore more collision can happen meaning more possibilities and therefore a higher reaction rate.  In part 3 of this lab (step 14) the rate of the sodium carbonate decomposition was greater with the powder than the solid because the powder had more surface area exposed.  The more surface area is exposed to molecules the more collision can happen meaning more possibilities/surface area for them to bump into one another and therefore a higher reaction rate.

Conclude and Apply

1.      Three methods I would suggest to decrease the reaction rate would be to

a.      Use a solid version of the powder: less surface area exposed meaning a smaller chance for particles to collide therefore the reaction rate decreases

b.      Dilute the concentration of the acid

c.      Cool down the acid: lower temperature means that particles move slower and therefore have a smaller chance with colliding with one another and therefore the reaction rate decreases.

d.      Add a catalyst like Potassium iodide: it will lower the energy of a reaction therefore speeding it up and will line up the molecules so that they can collide easier.

Conclusion

From this experiment I learned that some ways to increase reaction rate would be to add a catalyst, increase temperature and create more surface area. I also learned that amongst Potassium Iodide, Copper chloride and Sodium chloride, Potassium iodide and Copper chloride were catalysts and that Potassium iodide speedup the reaction rate the most.