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Flaming Unicorns Experiments

 

Experiment 1:  The Mass of Dissolved Salt (2.1)

Find a Video of our experiment HERE.

Problem:

How does the dissolving of salt in water affect the mass of the salt?

 

Hypothesis:

          If we dissolve salt in water, then the mass of the salt will decrease.

 

Independent Variable:

                        Dissolved salt

Dependent Variable:

          Mass of the salt

Constant(s):

                        Amount of water (mL)

                        Amount of salt (g)

 

Materials:

      Glass baby food jar with cap (1)

      2g of salt

      Electric scale

      86 mL of water

      Half sheet of paper

      Graduated cylinder

         

Procedure:

1.      Gather materials.

2.      Pour the water into the jar.

3.      Mass the water and the jar together.

4.      Mass the salt in the cap together.

5.      Add the masses together to get the entire apparatus’s mass before the dissolving  of salt.

6.      Pour the salt into the water, and then cap the bottle.

7.      Occasionally shake the bottle to speed up the dissolving process.

8.      Mass the apparatus again to find the new mass.

9.      Subtract the old mass from the new mass to get the change in the salt’s mass.

10.   Record data.

11.   Repeat steps 1 through 10 two more times or until you feel comfortable with your results.

 

 

Note:  Not actually a real test,  food coloring was used  for emphasis.

 

Data and Results:

 

 

Trial

Before (g)

After (g)

Difference (g)

 

1

165.7

165.8

+0.1

2

166.1

166.2

+0.1

3

166.1

166.1

0

4

163.3

163.3

0

5

164.9

164.9

0

6

166.9

166.9

0

7

166.3

166.3

0

8

166.7

166.7

0

9

163.9

163.8

-0.1

10

164.7

164.6

-0.1

11

162.5

162.4

-0.1

12

163.0

162.9

-0.1

13

164.0

163.8

-0.2

14

166.0

165.8

-0.2

15

164.2

163.9

-0.3

16

165.1

164.8

-0.3

17

162.7

162.3

-0.4

18

162.3

161.8

-0.5

19

163.0

162.5

-0.5

20

165.2

164.4

-0.8

 

 

 

   

Difference in Salts’ Mass

 

 

Conclusion:

            In conclusion, our hypothesis, if we dissolve salt in water, then the mass of the salt will decrease, was incorrect. We came to this conclusion because we have more trials that stayed the same than we do increases and decreases.  The sensitivity of the scale we used was plus or minus a tenth of a gram (0.1).  So all of the +0.1 and the -0.1 trials likely represent a change of 0.0g.  According to the data, there were twelve trials where it stayed the same (taking into account the sensitivity of the scale) out of the twenty trials that were conducted altogether.  Albeit there were two trials that increased, and multiple that decreased, but we are confident in our conclusion because the majority of the trials stayed the same and most of the changes larger than 0.1 grams can be accounted for in our sources of error.

 

Sources of Error:  

            One source of error was that some of the salt got stuck in the cap, fell out, or otherwise weren’t counted in our after numbers. This would lead us to conclude that the mass was decreasing, but we know it should have stayed the same because mass is conserved in chemical reactions. Another source of error was that in some trials, the cap wouldn’t go on all the way. When we shook the jar to speed up the process of dissolving salt, a tiny bit of water leaked out. Taking into account these errors, we believe that the mass stays the same before and after salt dissolves.    

 

Credited Links

Photo: http://theflamingunicorns.tumblr.com/

 

 

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