Lab Grade 9 - How Hot is the Water

How Hot Is The Water? Drake DePasquale, Lauren Zaur, Briana Duran, Brenda Guzman CHM 101 IA: Meron Teame Monday: 4:40-6:30 pm 19 November, 2025 Introduction The goal of this lab was to use the first law of thermodynamics to determine the temperature of the heated H2O. The first law of thermodynamics states that heat cannot be created nor destroyed; it can only be transferred. Applying this to the experiment, this helped determine the temperature of the H2O without directly measuring it. Three different trials were conducted and recorded in a data table to demonstrate how different temperatures of H2O change when mixed. Furthermore, after the experiment was completed, calculations revealed that the temperature of the heated H2O at the end of the experiment. Overall, one of the most important aspects of the lab is understanding how temperature changes are related to heat transfer when executing this experiment. Procedures The first step of the experiment was to collect materials. The materials included an electronic scale, one cup of heated H2O, one cup of cold H2O, a thermometer, and two Styrofoam cups. First, an empty Styrofoam cup was placed on the electronic scale, then tared to present the mass of the H2O that would be weighed out. Next, cold H2O was poured into one of the Styrofoam cups, filling it to approximately one-third of its volume. The cup containing the cold H2O was placed on the electronic scale again, displaying the mass of the cold H2O, which was then recorded in the data table. Then the thermometer was placed in the cup containing the cold H2O to determine its temperature. Afterwards, hot H2O was then poured into the second Styrofoam cup, filling one-third of its volume. The hot H2O was then poured into the cup containing cold H2O immediately after being poured. The thermometer was used once more to mix the liquid, then left in the cup for a minute to display the temperature of the final H2O product. Once the temperature had been taken, the styrofoam cup was then placed onto the scale, and the mass was recorded. This process was repeated for two more trials, in which the cold and hot H2O were filled to one-third of the cup each time. During the trials, the mass of the liquids varied, as did the combination of hot and cold H2O; meanwhile, the temperature of the cold H2O remained constant. Results Table 1 Trial # Mass of Cold H2O Temperature of Cold H2O Temperature of Combined Hot and Cold H2O Mass of Hot H2O (total mass - cold mass) Trial 1 68.887g 2°C 39°C 78.361g Trial 2 77.373g 2°C 33°C 57.162g Trial 3 73.788g 2°C 38°C 79.496g Calculations for the Initial Temperature of the Hot H2O MColdC∆TCold = –(MHotC∆THot) ​ MCold = mass of cold H2O ​ C(both) = 4.184 ​ ∆TCold = final temperature – initial cold temperature ​ MHot = total mass – cold mass ​ ∆THot = final temperature – initial hot temperature Trial 1 (68. 887)(4. 184)(39 − 2) =− ((78. 361)(4. 184)(39 − 𝑇𝑖) ​ 10664. 26 =− (327. 86(39 − 𝑇𝑖)) ​ 10664. 26 =− (12786. 54 − 327. 86𝑇𝑖) ​ 10664. 26 =− 12786. 54 + 327. 86𝑇𝑖 ​ 23450. 80 = 327. 86𝑇𝑖 ​ 71.50°C = Ti Trial 2 (77. 373)(4. 184)(33 − 2) =− ((57. 162)(4. 184)(33 − 𝑇𝑖)) ​ 10035. 59 =− (239. 17(33 − 𝑇𝑖)) ​ 10035. 59 =− (7892. 61 − 239. 17𝑇𝑖) ​ 10035. 59 =− 7892. 61 + 239. 17𝑇𝑖 ​ ​ 17928. 20 = 239. 17𝑇𝑖 74.96°C = Ti Trial 3 (73. 788)(4. 184)(38 − 2) =− ((79. 496)(4. 184)(38 − 𝑇𝑖)) ​ 11114. 24 =− ((332. 61)(38 − 𝑇𝑖)) ​ 11114. 24 =− (12639. 18 − 332. 61𝑇𝑖) ​ 11114. 24 =− 12639. 18 + 332. 61𝑇𝑖 ​ 23753. 42 = 332. 61𝑇𝑖 ​ 71.42°C = Ti Average Temperature Found 71. 5 + 74. 96 + 71. 42 = 217. 88 217. 88 ÷ 3 = 72. 6 °C Percent Error 𝑓𝑜𝑢𝑛𝑑 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒−𝑘𝑛𝑜𝑤𝑛 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 | 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝐸𝑟𝑟𝑜𝑟 = || | × 100 𝑘𝑛𝑜𝑤𝑛 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 | 72.6−72 | × 100 = 0. 833% | 72 | Discussion The purpose of the lab was to identify the temperature of the hot H2O without directly measuring it, and to utilize the concept of the first law of thermodynamics. From the three trials, the average calculated hot H2O temperature was 72.6 °C, whereas the actual temperature of the hot H2O was 72 °C. After calculations were complete, a percent error of 0.833% was found. This means that the purpose of the experiment was achieved, as the calculated temperature value was extremely close to the actual temperature of the heated H2O. One possible error that may have occurred is the heating of the cold H2O in the second trial. This is because the cold cup of H2O was held in a group member's hand for a lengthy period of time before conducting the second trial. This likely means that a heat transfer could have occurred, further displaying the first law of thermodynamics. Having an isolated cup that is resistant to heat may prove to be much more effective in finding accurate temperatures. Another error that occurred was a difference in the time before measuring in each trial. Trial two was the only trial where the temperature was recorded and measured a significant time after stirring. Compared to trial two, trials one and three, the H2O solutions were given different amounts time to mix before the temperature was taken. This means that results may be more accurate for trials one and three. Overall, a key takeaway uncovered from this experiment was to ensure the consistency of variables across different trials.