Chemistry, in a BAG!

Materials:



-9 sandwich bags



-phenol red




-calcium chloride (rock salt)




-sodium bicarbonate (baking soda)




-water




-safety goggles




Procedure:
PUT ON SAFETY GOGGLES-



PHENOL RED STAINS, CALCIUM CHLORIDE IS AN IRRITANT.

1. Place all four chemicals in a baggie, liquids in one corner and solids in the other, and make sure that they do not touch by pushing the baggie with your hand in between the corners.

2. Prepare to take observations.




3. Remove your hand from under the bag and begin mixing the materials.







4. Record observations.




5. Throw away baggie.




6. Place phenol red and calcium chloride in opposite corners of a new baggie and separate them as in step 1.




7. Repeat steps 2, 3, 4, and 5 with the phenol red and calcium chloride baggie.




8. Place phenol red and sodium bicarbonate in opposite corners of a new baggie and separate them as in step 1.




9. Repeat steps 2, 3, 4, and 5 with the phenol red and sodium bicarbonate baggie.




10. Place water and calcium chloride in opposite corners of a new baggie and separate them as in step 1.




11. Repeat steps 2, 3, 4, and 5 with the water and calcium chloride baggie.




12. Place water and sodium bicarbonate in opposite corners of a new baggie and separate them as in step 1.




13. Repeat steps 2, 3, 4, and 5 with the water and sodium bicarbonate baggie.




14. Place phenol red, water, and calcium chloride in opposite corners of a new baggie and separate them as in step 1.




15. Repeat steps 2, 3, 4, and 5 with the phenol red, water, and calcium chloride baggie.




16. Place phenol red, water, and sodium bicarbonate in opposite corners of a new baggie and separate them as in step 1.




17. Repeat stets 2, 3, 4, and 5 with the phenol red, water, and sodium bicarbonate baggie.




18. Place phenol red, sodium bicarbonate, and calcium chloride in opposite corners of a new baggie and separate them as in step 1.




19. Repeat steps 2, 3, 4, and 5 with the phenol red, calcium chloride, and sodium bicarbonate baggie.




20. Place water, sodium bicarbonate, and calcium chloride in opposite corners of a new baggie and separate them as in step 1.




21. Repeat steps 2, 3, 4, and 5 with the water, sodium bicarbonate, and calcium chloride baggie.

OBSERVATIONS:
All four materials:

Turned yellow, produced a gas, exothermic reaction, and later endothermic reaction

Phenol red and calcium chloride:

Turned magenta, produced heat

Phenol red and sodium bicarbonate:



Turned magenta, became a bit cold




Water and calcium chloride



Became very hot, water became almost opaque




Water and sodium bicarbonate



Became a bit cold, water became almost opaque




Phenol red, water, and calcium chloride



Became hot, dark magenta color




Phenol red, water, and sodium bicarbonate



Became a bit cold, was reddish-magenta







Phenol red, calcium chloride, and sodium bicarbonate:



Became warm, then cold, produced gas and was yellow







Water, calcium chloride, and sodium bicarbonate



Became warm, produced gas







Lab Questions:



1. Based on the results of the controlled experiments, what combination of substances seems to be responsible for the observed temperature change in the overall reaction?

Water or phenol red mixed with calcium chloride produced heat, and water or phenol red mixed with sodium bicarbonate caused an endothermic reaction.


2. Was there a temperature change observed in any of the controlled experiments that was NOT observed in the overall reaction in part A? Explain.

No, the controlled experiments became both hot and cold, and so did the overall reaction.


3. What color change was observed in the overall reaction? Do the controlled experiments provide any evidence concerning the combination of chemicals responsible for the observed color change?

It became yellow; yes, phenol red, sodium bicarbonate, and calcium chloride became yellow also.


4. Are temperature or color changes always observed at the same time as the formation of gas bubbles? Explain.

No, usually the gas bubbles appear before the temperature change, but after the color change.


5. What controlled experiments were done to evaluate if a liquid is necessary for the observed effects in part A? Does any reaction occur in the absence of water?

All of the experiments without water; yes, phenol red causes reactions with different substances without water being present.

6. What evidence suggests that a new chemical substance is produced in the overall reaction of the substances mixed in part A? What combination of chemicals may be responsible for the new substance?

The filling of the baggie with gas is a key to identifying if a new chemical is produced. Obviously, the gas wasn't compressed inside the baggie when we closed it, so the gas must have been created by the chemical reaction. Water, calcium chloride, and sodium bicarbonate created the gas. This may be because either (a) the calcium chloride cannot react with the sodium bicarbonate while in a solid state or (b) the water needs to react with both of these chemicals to produce a gas.

7. Let's assume that the chemical identity of calcium chloride is not changed when it is mixed with water. Suggest an experiment that could be done to test this hypothesis.

After mixing the calcium chloride and the water, you could let it sit out to evaporate the water, and if what remains in the dish has the same properties as calcium chloride, it proves that the water does not change the chemical identity for the calcium chloride.

8. Temperature changes are sometimes used as evidence to indicate that a chemical reaction has occured. Discuss whether a temperature change always indicates that a chemical reaction has occured.

I do not think so, because the calcium chloride mixing with the water produced heat, but no new chemicals were generated by the chemical reaction, and I don't think either of their chemical formulas changed.

*Sorry if the spacing is all messed up, this doesn't always save correctly for some reason.