Liquids and Solids Purpose: The goal of this experiment is to be able to identify melting/boiling points of substances. We can then use these methods to identify unknown substances because of constants in melting/boiling points. Procedure: 1. Boiling Point a. Begin by adding 1 mL of rubbing alcohol to test tube and attach a thermometer to it.
In this step, as we watched the chemical reaction with the solids, we noticed a thinning in the substance. Also, the solids became lighter and moved to the top. When stirred, the solution began to turn green and then back to light blue, where copper began in the end of the first step. A combination reaction took place, and the balanced equation is: CuOs+H2SO4aq→CuSO4aq+H2O(I) Following this step, step 5 began, in which we added 300 mg of zinc to the solution. Once the zinc was added slowly to the solution, a gas was released and the solution began to change colors.
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.
To observe the change in properties of various synthesized copper compounds in order to identify the reactions and products being formed. Secondly, to become familiar with methods of separating compounds through decanting, heating with Bunsen burner and suction filtration system. In doing so, be able to recover copper metal and interpret the resulting percentage yield by applying the law of conservation of matter. Upon combining 20.0mL of NaOH to 10.0mL of Cu(NO3)2 and stirring the solution, there was a darkening of the initial blue color. Adding distilled water to the solution lowers the initial intensity of the blue color, bringing back to a lighter blue.
Wait for the bubbling to subside between additions so that the reaction does not overflow the flask. 6. When all the acetic acid has been added, swirl flask or stir for two minutes with a glass stirring rod. 7. When the solution is completely calm, move the flask to a hot plate and heat it to boiling.
After all the acid has been completely added and the reaction has stopped, use a pipette to add a few extra drops of acid into the beaker until the reaction stops. 7. Place the beaker on a hot plate and heat on a high setting to boil off the water. WARNING: THERE WILL BE A SMALL AMOUNT OF HYDROCHLORIC ACID BOILING OF THE MIXTURE. DO NOT PLACE YOUR FACE DIRECTLY ABOVE THE BEAKER.
Distillation is used to purify a compound by separating it from a non-volatile or less-volatile material. When different compounds in a mixture have different boiling points, they separate into individual components when the mixture is carefully distilled. The boiling point is the temperature at which the vapor pressure of the liquid phase of a compound equals the external pressure acting on the surface of the liquid. The external pressure is usually the atmospheric pressure. Different compounds boil at different temperatures because each has a different, characteristic vapor pressure: compounds with higher vapor pressures will boil at lower temperatures.
While stirring, 6 M NaOH was added drop-wise until the solution became basic, turning red litmus paper blue. A total of 3.84 mL NaOH was required to achieve this; the resulting solution appearing dark blue with cloudy precipitates. The solution was then heated gently atop a hot plate to catalyze the next reaction, with care taken to assure all residue was kept off the walls of the beaker. Heating continued until the reaction reached completion and the solution slowly changed from blue to a dark green and finally black. At this point the heat was turned off to allow the black solid in the beaker, CuO, to settle to the bottom.
4) Ignoring step 3, after step 2, you can take the solution that you have created and pour it into a 100 mL beaker. Once the solution is in the beaker, turn on the conductivity tester and gently place it in the solution (try not to touch the bottom of the beaker). Record the results. 5) Now, take the beaker with the solution already inside and place it on a hot plate. Turn on the hot plate to a medium heat.