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to introductionChemical Reactions Lab
(adapted from the GEMS
hall of science series of labs)
Introduction:
The combination of two or more chemicals to react to form a third chemical is called a reaction. Reactions are indicated by one or more of the following things, a color change, a heat change, the release of gas. In this lab we will see all three and then try to sort out what is happening.
The chemicals we will be using for this lab are: Calcium Chloride (CaCl2), Baking soda (NaHCO3), and phenol red.
The mixing will take place in a plastic sealed zip lock bag, this way the gas released can be observed as well as the other parts of the reaction.
Purpose:
The purpose of this lab is for students to experience the different
types of reactions that we have studied in class.
Materials List:
| vial
= film canister graduated cylinder measuring spoon stick for leveling zip lock bag phenol red Calcium Chloride Baking Soda goggles apron gloves Styrofoam cup\ for temp/time thermometer / experiments pencil/paper buckets |
Safety Notes:
In this lab you will be combining three chemicals and observing their reactions. In the first stage you will carefully mix all three of the chemicals in the plastic bag. It is important that you measure carefully!! Follow the directions carefully.
In the second phase you will try to figure out (deduce) what is causing the heat, gas, and color change. Before conducting any of the experiments you must first write down a hypothesis, or what you think will happen. After you have done this you may measure and mix. You will always keep the proportions the same as in the first trial, can you explain WHY?
In all you will be conducting four experiments, Between each experiment you will need to carefully wash out your plastic bag and film can in the sink. You MUST wear the rubber gloves when washing out the bags.
Safety Notes: Do NOT taste anything in this lab.
You must wear your goggles at all times in this lab.
Buckets have been provided for you if you think that your bag looks like it is going to burst open, place it in the bucket and do NOT look over the edge.
Procedure
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OBSERVE EACH
REAGENT (chemical) ALONE:
Calcium Chloride (CaCl2)
Baking Soda (NaHCO3)
Phenol Red Solution
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Begin the experiment by combining all the chemicals in the ratio described below.
( 5ml=1 teaspoon )
1. Put 5 milliliters of Baking Soda (NaHCO3) into a zip lock bag.
2. Put 10 milliliters of Calcium Chloride (CaCl2) into the same bag.
3. Measure 10 ml of Phenol Red solution, and pour into a vial ( use a graduated cylinder to measure liquid ).
4. Put the vial into the bag ( standing upright ) and make sure the bag is well sealed.
5. Tip the vial of Phenol Red solution.
Record your Data
Describe your preliminary results here ( Data )
CaCl2 + NaHCO3 + Phenol Red ( C19H13O5S)
--------yields -------> _____________________________________________________________
Now, try to figure out what combination of chemicals is causing the heat by creating your own experiments.
The HEAT experiments
Combine any two of
the three
chemicals in the same ratio as used above, determine what caused the temperature
change
Repeat your experiment 3 times each with a different combination
of chemicals
Describe your first experiment:
your plan:
_______________+ ___________________---------------> ___________________________
your idea of what will happen when you combine these two things: (hypothesis)
What happened?
What can you conclude?
Describe your second experiment:
your plan:
_______________+ ___________________---------------> ___________________________
your idea of what will happen when you combine these two things: ( hypothesis )
What happened?
What can you conclude?
Describe your third experiment:
your plan:
_______________+ ___________________---------------> ___________________________
your idea of what will happen when you combine these two things: ( hypothesis )
What happened?
What can you conclude?
Conclusion
Which chemicals caused the heat, why do you think this happened?
Design an experiment that will allow you to measure the temperature of your combination at regular intervals of time. ( I suggest every 15-30 seconds. )
Write out your procedure below.
Create an appropriate data table. Check these with me, then begin your experiment.
Graph the results of your experiment . ( If possible use the computer to do the graphing. )
When you have completed these steps, change 1 of the quantities of a chemical or one of the chemicals and redo the experiment. Do this at least one time.
Graph your data.
Optional Extension
What would happen if you substituted a different type of liquid into the reaction, not water or phenol red, but lemon juice or milk for example?
What must you keep constant in your new experiment? Try it and discuss the results.
1. During the lab many types of reactions occurred. Describe the process that you used for deducing the reagents that when combined formed the heat, cold, gas, and color change.
2. What was the purpose of the Phenol Red in the experiment?
3. Now that you know the chemical formula of this reaction and something about reaction types, what type of reaction would you classify this as ? (single or double displacement, synthesis or decomposition) Defend your position, there are two reactions in all.
4. What was the limiting reagent that determined how much gas was produced? How do you know?
5. If you had more time, how would you design an experiment to measure the temperature change as a function of time more accurately?
6. What would happen if you substituted a different type of liquid into the reaction, not water or phenol red, but coke or an acid for example? Try it and discuss the results. What must you keep constant in your new experiment?
7. How would you improve or change this lab?
8. What have you learned from doing this lab that you didn't already know?
Need help ? check here Chem4Kids!
Your Chemistry Website! at the reactions section.
Interested in more home labs? Check here you can with beakman and jax or look at the web activities page
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