Heat Of Solution Lab Report 4t1c4w

Heat of Solution Lab INTRODUCTION In this experiment, change in water temperature was tested by dissolving different types of salt into water. The objective of this experiment was to find the most effective deicing agent of the three salts tested. Salt was added to 30mL of water at room temperature, the most effective salt for deicing roads would be the salt which raised the water’s temperature the most. The expected outcome was that the calcium chloride would cause the greatest increase of temperature in the distilled water. Since this was true, it means that calcium chloride causes an exothermic reaction, and released the most heat energy into the water. uses salt during the winter season to remove snow and ice from roads and sidewalks to keep people safe. It is important that the salts they chose be tested for effectiveness and environmental impact.

PROBLEM What effect does the type of salt have on the change in temperature of water in °C?

HYPOTHESIS If calcium chloride is added to water, then the temperature of the water will increase because it causes an exothermic reaction where the salt releases heat into the water.

VARIABLES Independent Variable: Type of salt (sodium chloride, calcium chloride, ammonium chloride) Dependent Variable: Change in temperature of the water (°C) Constants: -Volume of distilled water (30 mL) -Mass of salt (5 grams) -Stirring (2 minutes) Control: 30 mL of distilled water which has no salt added, that is stirred for 2 minutes. Take the initial and final temperature.

MATERIALS           

50 mL beaker 120 mL of distilled water Graduated cylinder Thermometer (Celsius) Stopwatch (use phone) 3 spatulas, one spatula per salt (5 grams) 1 weigh boat 3 digital scales, one per salt 5g of Sodium Chloride, NaCl 5g of Calcium Chloride, CaCl₂ 5g of Ammonium Chloride, NH₄Cl

SAFETY      

WEAR GOGGLES AND AN APRON AT ALL TIMES HANDLE ALL GLASSWARE CAREFULLY DO NOT MIX THE DIFFERENT SALTS TOGETHER CLEAN UP ALL SPILLS IMMEDIATELY NO FOOD OR DRINKS ALLOWED IN THE LAB WASH HANDS AFTER CLEANUP IS COMPLETE

PROCEDURE 1. Measure out 30 mL of distilled water using the graduated cylinder. 2. Pour the 30 mL of distilled water into the 50 mL beaker. 3. Using the thermometer, record the initial temperature of the water ℃. Record data in data table 1. 4. Place empty weigh boat on the digital scale and zero the scale 5. Using the spatula, measure 5g of sodium chloride into the weigh boat.. 6. Pour the sodium chloride into the beaker containing 30 mL of distilled water 7. Stir solution constantly using the thermometer for two minutes with the stopwatch (on phone). 8. Record the final temperature of the water using the thermometer (℃) in data table 1. 9. Discard of the solution in the labeled waste beaker in the hood. 10. After data has been recorded, clean the weight boat, beaker, and the thermometer, with the Alconox soap and water. 11. Completely dry all materials using paper towels. 12. Repeat steps 1-11 using calcium chloride instead of the sodium chloride. 13. Repeat steps 1-11 again using ammonium chloride instead of the sodium chloride. 14. Repeat steps 1-3 and 7-11 to find the control.

RESULTS Data Table 1: The effect of Salt (g) on the Change in Temperature (℃) of Water Type of Solute

Initial Temperature Final Temperature (℃) (℃)

Change in Temperature (℃)

Sodium Chloride

24

23

-1

Calcium Chloride

24

38

14

Ammonium Chloride

24

16

-8

Distilled Water (Control)

24

24

0

Calculations The Change in Temperature is calculated by subtracting the initial temperature by the final temperature. Formula: Final Temperature-Initial Temperature=Change in Temperature

Calculations: (Sodium Chloride) 38°-24°=14°

SUMMARY In the experiment, calcium chloride produced the greatest change in temperature from 24℃ to 38℃ with a 14℃ difference in temperature. The salt with the least change in temperature was the sodium chloride which decreased in temperature by 1℃, starting at 24℃ and ending at 23℃ Ammonium chloride decreased the most in temperature, but by 8℃, starting at 24℃ and ending at 16℃. The control on the other hand didn’t change in temperature at all, starting and ending at 24℃ and stayed the same. The graph represents the data because it shows how each bar changes with the data relative to the x-axis. For example the calcium chloride increased by 8℃ and the bar increased above the x-axis. Also Ammonium chloride decreased from the x-axis 8℃, to show that the ammonium chloride decreased the waters temperature. Sodium chloride also decreased the water’s temperature, and made the bar decrease but not as drastically as ammonium chloride. The control does not have a bar to represent it because the temperature stayed the same, and didn’t change in temperature.

CONCLUSION The hypothesis of this experiment suggests that the calcium chloride salt would be the most effective salt for increasing the temperature of the distilled water. Based on the data that we recorded, the hypothesis was proven to be correct.

The data states that calcium chloride increases the temperature of the water substantially more than the other salts did. The data shows that the sodium chloride decreased the temperature of the water by -1℃. The calcium chloride’s change in temperature ended up as an increase of 14 ℃. The ammonium chloride’s change in temperature was -8℃. Since the calcium chloride’s change in temperature was

the greatest increase, this data proves the hypothesis correct. Calcium chloride has the largest increase in temperature because when it comes in with ice, it forms a brine faster than any of the other solutes, which lowers the freezing point of the ice. The Calcium Chloride mixed with water causes an exothermic reaction which releases heat energy into the water. This salt was the only to increase the temperature of the water. Ammonium Chloride and Sodium Chloride both created an endothermic reaction with the water because the temperature decreased and heat energy went from the water into the salt. Based off of this, we know that calcium chloride is the most effective to deice roads because it increased the temperature the most.

VALIDITY One improvement that could be made to the experimental design is to have more than 5 grams of each type of salt. With using only 5 grams of salt in each trial, there is only a slight change in temperature. If the experimental design was changed to using 10 grams of each type of salt, there would be a more obvious change in temperature which would lead to more clear and valid results. Three variables that were held constant in this experiment were volume of distilled water (30 mL), mass of salt (5 grams), and stirring (2 minutes). Keeping the volume of water constant affects how much the salt changes the temperature of the water. If their were different masses of salt in each trial, then the results would be invalid because a person would not know how that change was different between salts. Having the salts the same mass would make the experiment more valid because the results would not vary because of the mass of the salt, but because of the type of salt if you were to make the masses different what would change about the data?? give an example.. Finally, stirring each type salt constantly for two minutes with the thermometer, the water is key to the experiment’s validity because it dissolves the salt into the water for the same??? why is this important to keep constant? how would the data change if you did not do this each time? at a faster pace.

ENVIRONMENTAL IMPACT Every winter across the United States, millions of pounds of deicing agents are poured onto roads and sidewalks to improve ways of travel. It is believed that in the U.S, 22 million pounds of salt are used each year to keep the roads clear. Although we believe that this is very helpful, it’s also very harmful. As the snow and ice melts, it carries the now chemical filled water into local streams and rivers and into the drinking water. An estimated 40 percent of the country's urban streams have chloride levels that exceed safe guidelines for aquatic life, largely because of road salt. There has been an ongoing study of a stream in southeastern New York. From 1986 to 2005, there has been an increase of 91% of sodium chloride in the water, mostly due to road salts. Salt is also highly corrosive. It corrodes cars, bridges, roadways, and other forms of infrastructure. Salt is so destructive and corrosive that in 2004 Canada declared that road salts are toxins. While eliminating ice using these deicing agents is great, we also need to consider all of the downfalls that come with it, including the destruction of infrastructure and the harming of the local ecosystems.

WORK CITED

Stromberg, Joseph. "What Happens to All the Salt We Dump On the Roads?"Smithsonian. Smithsonian, 6 Jan. 2014. Web. 8 Dec. 2015. "Deicing - The Environmental Literacy Council." The Environmental Literacy Council. Environmental Literacy Council, n.d. Web. 08 Dec. 2015.