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What Is The Effect Of Salt on The Buoyancy of an Egg?
Transcript of What Is The Effect Of Salt on The Buoyancy of an Egg?
by: Dejah Washington
Ms. Amburgey’s 8th Grade Science ADV How Salty Does the Sea Have to Be for an Egg to Float? Title Testable Question: What Is The Effect Of Salt On The Buoyancy Of An Egg? Hypothesis: If more salt is added to the water, then the egg will float ,because once the salt is added to the water, the solution will become more dense than the egg. Variables: Tested (Independent) Variable: the amount of salt that is added to the water.
Outcome (Dependent) Variable: the buoyancy of the egg
Controlled Variables: The amount of water used in each cup. Materials
Bag of clear 16-oz. plastic cups
Measuring cup, liquid
Container, 1-quart (qt.)
Spoon for stirring
Spoon for egg transfer
Lab notebook Procedure 1. Take one egg out of the refrigerator and allow it to warm to room temperature.
2. Make a stock solution of 1 cup of salt dissolved in 1 qt. of water, as follows:
a. Pour 3 cups of water into your 1-quart container.
b. Add 1 cup of salt.
c. Stir to dissolve.
d. Add more water to make 1 qt.
e. Stir to mix completely.
3. Make a two-fold serial dilution of the stock solution, as follows:
a. Label four of the plastic cups 1–4. Label the fifth cup Tap water. Cup 1 will be for the stock solution, cups 2–4 will be for the dilutions.
b. Add 3/4 cup of your stock salt solution to cup 1.
c. Add 3/4 cup plain tap water to cups 2–5.
d. Measure out 3/4 cup stock solution, and add it to cup 2. Mix.
e. Measure out 3/4 cup of the solution from cup 2 and add it to cup 3. Mix.
f. Measure out 3/4 cup of the solution from cup 3 and add it to cup 4. Mix.
g. What are the relative salt concentrations of cups 1–4? Procedure 4. Now, starting with cup 5 and working your way up, test the egg in each solution to see if it will float. Use a soup spoon to lift the egg in and out of the cups.5. In which cup did the egg first float? (Save this solution for step 7.) If the egg floated in more than one cup, did you notice any difference in how it floated?6. Now you know, within a factor of 2, how much salt it takes to float an egg. How can you narrow down the range further to get a more precise estimate? By doing another serial dilution, of course. 7. This time you will start your dilution with same the salt concentration in which the egg first floated.
a. Figure out a new serial dilution with smaller steps. For example, you could try diluting the solution by 20 percent with each step. That means with each step, the new concentration should be 80 percent of the original concentration.
b. What amounts of stock solution and water do you need to use? (Remember that you will need enough solution to more than cover the egg.)
c. Write up your new dilution procedure in your lab notebook, including the calculated salt concentrations for each cup.
d. Make the new dilution series. Remember to start with salt concentration where the egg first floated. (If you don't have enough solution from the original serial dilution, make some more by starting from the stock solution.) Procedure 8. As before, test the egg in each cup, starting with the lowest salt concentration. In which cup did the egg float first?
9. If you want, make another dilution series, with even smaller steps, to improve the precision of your estimate.
10. Repeat the entire procedure with the four other eggs. Plot the densities for all five eggs on a chart. How much variation in density is there from egg to egg? Procedure Data TRIAL 1 CUP CONTENTS FLOAT 5 4 3 2 1 160 ml tap water no 345 ml solution no 150 ml solution no 150 ml solution no 145 ml solution yes Data TRIAL 2 CUP CONTENTS FLOAT 5 4 3 2 1 160 ml tap water no 345 ml solution no 150 ml solution no 150 ml solution yes 145 ml solution yes DATA TRIAL 3 CUP CONTENTS FLOAT 5 4 3 2 1 160 ml tap water 345 ml solution 150 ml solution 150 ml solution 145 ml solution (no extra water) (no extra water) (no extra water) no no no no yes PICTURES PICTURES CUP #1 CUP #2 CUP #3 CUP #4 CUP #5 GRAPH no yes Did the egg float? trial 1 trial 2 trial 3 cup #1 trial 1 trial 2 trial 3 cup #2 trial 1 trial 2 trial 3 cup #3 trial 1 trial 2 trial 3 cup #4 trial 1 trial 2 trial 3 cup #5 = trial 1 = trial 2 = trial 3 Analysis: 1.What patterns or trends do you see in the graph/data? Cup number 1 was the only cup where the egg floated in each trial. 2.What factors could have influenced your data? Cup number one consisted of 3/4 cup of the solution, while the other cups consisted of the solution and extra water added. There was more salt in cup 1 than any other cup. This could be why the egg only floated in cup number 1. Conclusion The data supported my hypothesis because there was more salt and less water in cup number one than in any other cup. In cups 2-4 there was less salt and more water. In cup 5 there was no salt at all. The egg floated the highest in cup number 1, where there was a higher quantity of salt. Once the salt was added to the water, the solution became more dense than the egg. Research ONR. (n.d.). Resources: Experiments—Saltwater vs. Freshwater, which is Denser? Retrieved December 29, 2012, from http://www.onr.navy.mil/Focus/ocean/resources/water2.htm
I learned that an egg has a greater density than freshwater, but not saltwater. eHow.How Does Salt Water Make An Egg Float?
Retrieved December 29,2012 from http://www.ehow.com/how-does_4962595_salt-water-make-egg-float_.html
I learned that if you add salt to the freshwater without stirring it, that will cause the egg to float in the middle of the water, not on top.