The second case study was covered in an article by Science News. In this study, two different types of water were used, distilled and tap water. The tap water was heated to 100 degrees Celsius and the distilled water was cooled to 25 degrees Celsius. They were placed into identical copper containers. The test was completed 27 times and each time the hotter tap water froze before the cooler water.
Heats of Solution and Reaction Name: Cindy Hernandez Purpose: The purpose of this experiment is to decided if the chemical reactions are exothermic and endothermic. By finding the differences between each temperature. Overview: For this lab, we had three different chemicals involved NH4Cl, H2SO4, and NaOH. What we did with these chemicals was that we added water, except NaOH we added HCl, was that we combined both mixtures to determine if there was a temperature change. The reason why we're determining if their was a chemical reaction is to identify if it is exothermic or endothermic.
Materials: 3 beakers Thermometer 3 Alka-Seltzer tablets Stopwatch Mortar and pestle Source of hot water Ice cubes Graph paper Procedures: Hot water- Run water from the hot tap until it is hot as possible Fill beaker with 80 mL of hot water Use thermometer to take temperature of water. Record in data table. Remove 1 Alka-Seltzer tablet from package Drop into the water. Measure the time it takes for the tablet to completely dissolve. BE READY WITH THE STOPWATCH.
We selected a spirit burner and recorded the name of the fuel into our table; we also included the mass of the whole burner. We then clamped the steel can so that the spirit burner will fit under it. We light the wick of the spirit burner and placed it underneath the can. After we used the thermometer and to gently stir the water when the temperature increased by 20 we put the lid on the burner to put the flame out, we then recorded the new mass of the whole burner including the lid and fuel inside. We repeated thus experiment twice with each fuel, using clean water each time.
n (3) Solutions of aqueous sodium hydroxide and hydrochloric acid react to form water and aqueous sodium chloride. co NaOH(s) → Na+(aq) + OH–(aq) ∆H1 = ? Chemistry with Vernier py In this experiment, you will use a Styrofoam-cup calorimeter to measure the heat released by three reactions. One of the reactions is the same as the combination of the other two reactions. Therefore, according to Hess’s law, the heat of reaction of the one reaction should be equal to the sum of the heats of reaction for the other two.
Next we will measure equal amount of water. Boil hot tap water first, then cold tap water and last room temperature bottled water. The cup used to measure all three types of water will be the same. Independent Variable - hot water, cold water, room temperature water Dependent Variable - Amount of water ( 3 cups) Controlled Variable - Pot size, Heat. The outcome of this experiment will help us determine which water rolling boils faster thus saving time.
First I made a water bath by filling the 100 mL beaker with cool tap water. I then placed crushed ice in the 100 mL beaker so the water level was just below the top of the beaker. I sprinkled a little salt in the ice water and mixed it well. I then filled the test tube half full with distilled water and set the test tube in the 24 well plate. I inserted the digital thermometer into the test tube and took reading every 30 seconds until the readings remained constant.
At first we dried the crucible in the flame three times and let it come to a constant mass by measuring the weight each time. To determine percentage of water in Epsom salt, we measured about 2g of the salt into three different, dried crucibles. The crucibles were first heated gently, then intensely to drive off all the water. The final data was reported as percent hydrate with 95% confidence level. RESULTS & DISCUSSION Weights of the crucible.
Hydrate Lab The purpose of this lab is to analyze the percent water in a crystalline hydrate and to indentify the hydrate from a list of possible unknowns. The solid hydrate will be heated to remove the water, and the percent can be found by measuring the mass of the solid before and after heating. The hydrate will be indentified by comparing the percent water in the hydrate with the percent water calculated for the possible unknown. Before the lab there are pre-lab questions: 1. Describe the three general safety rules for working with a Bunsen burner.
For observing the reaction, use 8oz of water at four different starting temperatures: hot tap water, cold tap water, water heated in microwave, and ice water. a. For the hot and cold tap water, run the water until the temperature stabilizes. Fill the pyrex measuring cup to 8 oz. b.