Inquiry 3 Report PDF

Preview

Summary

Inquiry 3 Report...

Description

!1 Anna Balcerek SEMS 360 Inquiry 3 Report 1. Title of project: Salt vs Sugar 2. Abstract I experimented the rate of solubility of table salt and sugar in room temperature water. I predicted that sugar will dissolve faster in water than salt. The substances were poured into room temperature water, stirred and timed until they had completely dissolved. Using a t-test I was able to reject my null hypothesis. Therefore, my data supports my alternative hypothesis saying that sugar will dissolve faster in water than salt.

3. Introduction When there is more energy present, the rate of dissolving increases. So, if you heat up the solvent the molecules will have more kinetic energy. Additionally, stirring a solution will increase the rate at which the solute dissolved. Stirring the solution allows fresh solvent molecules to continually be in contact with the solute. If the solution is not stirred it will just simply take a longer time to dissolve. When a solution is not stirred, then the water right at the surface of the solute becomes saturated with dissolved sugar molecules. Therefore, it is more difficult for the solute to dissolve. Also, the surface area of the solute particles affect the rate at which it dissolves. For example, a packet of granulated sugar which exposes more surface area to the solvent will dissolve more quickly than a sugar cube. (CK-12 Foundation)

My overarching question is “What dissolves faster in water sugar or salt?” Null Hypothesis: Salt and sugar dissolve in water at the same rate.

!2 Alternate Hypothesis: Sugar dissolves faster in water than salt. Experimental variable: substance being dissolved in water Controlled variables: temperature of water, amount of water, amount of sugar, amount of salt, amount of time solution is stirred, same glass, rate of stir

The solution will be considered completely dissolved when it is completely clear and no longer foggy and white.

4. Experimental Design Materials list Water (1 cup) Two glasses for the water Timer Table salt (1 tablespoon) Table sugar (1 tablespoon) Tablespoon Safety: Wash hands after the experiment. Do not touch near eyes and face after touching salt or sugar. Procedure: 1. Fill glass with half a cup of water. 2. Pour a tablespoon of table salt into the glass of water and immediately start the timer once all of the salt has entered the water. 3. After hitting the timer, stir the solution 20 times with the tablespoon. 5. Wait for salt to dissolve completely. 6. Stop timer once salt has dissolved. 7. Repeat steps 1-6 three times. 8. Repeat the same procedure using sugar instead of salt.

!3 5. Results and Analysis Table 1:

Salt Trial

Time

1

1 min 43 s

2

1 min 47 s

3

1 min 46 s

Table 2:

Sugar Trial

Time

1

42 s

2

42 s

3

40 s

Table 1 displays the results for how long it took for a tablespoon of table salt to dissolve in half a cup of water. For trial 1, the salt dissolved in 1 minute and 43 seconds. For trial 2, the salt dissolved in 1 minute and 47 seconds. For trial 3, the salt dissolved in 1 minute and 46 seconds. Table 2 presents the time it took for a tablespoon of table sugar to dissolve in half a cup of water. The times are displayed in seconds for each of the three trials.

I performed a t-test for my data and collected the following information:

!4

Sugar Mean =

41.3 s

Standard Deviation =

0.011547

Variance =

0.000133

n=

3 Salt

Mean =

1 min 45 s

Standard Deviation =

0.020817

Variance =

0.000433

n=

3

I used the equation above to calculate my t-value which is equal to 75.497. p = 1.6 x 10^(-6) d.f. = n1+n2-2 = 4, α = 0.05 Critical point = 2.78, Since, my t-value 75.497 is higher than my critical point 2.78 and my p-value is less than 0.05, I may reject my null hypothesis.

!5 6. Conclusions After conducting three trials comparing the rates at which salt and sugar dissolve, I observed that the times collected for how long it took for sugar to dissolve were much lower than the time it took for the salt to dissolve in the water. Then, I performed a t-test to analyze my data. Since, my t-value 75.497 is higher than my critical point 2.78 and my p-value is less than 0.05, I may reject my null hypothesis. Therefore, at the 0.05 significance level, I may conclude that sugar dissolves faster in water than salt.

7. Implications and limitations The type of salt used may affect results. For example, rock salt may dissolve at a slower rate than table salt since table salt exposes more surface area to the solvent than rock salt would. The solution in the end will never become completely clear after the substances dissolve. What is considered clear may differ from person to person so, results may vary. I noticed that the sugar water solution appeared more clear compared to the salt water solution. Possibly, more water in the salt water solution would help the solution appear more clear. Therefore, it may take a greater amount of water to dissolve salt compared to sugar. Also, the temperatures of the water I used to dissolve the salt and sugar in each trial may vary because I used running tap water. Therefore, I cannot guarantee the temperature of the water was exactly the same for each trial. Additionally, the rate at which I stirred each substance may vary. Although I did stir each solution 20 times and then waited for the solute to completely dissolve, how fast I moved my hand to stir the solution may have varied between each trial since I cannot be sure if I moved my hand at the same rate each time.

!6 Works Cited CK-12 Foundation. “Rate of Dissolving.” CK-12 Foundation, CK-12 Foundation, 7 Sept. 2018, www.ck12.org/book/CK-12-Chemistry-Concepts-Intermediate/section/16.3/....