In all, based on the observations made throughout this part of the experiment and discussed in the results above, the confirmation of silver was justified since lead and silver each have distinct characteristics and unique responses that were expected to occur with each reagent. The observations that would have been made if lead was present, such as the critical formation of yellow precipitate when K2CrO4 was added, was negative. However, the results that were expected if silver was present were all justified with clear and evident results gathered throughout each step, and characterized based on insolubility, the formation of white precipitate when HNO3 was introduced, and the confirmed acidic solution. PART B With regards to Part B, once the initial two steps of this step were conducted, K2CrO4 was added. This reagent served to help identify whether Ca2+ or Ba2+ was present based on solubility and the presence of precipitate. On the principle of solubility, since the anion CrO42- forms mostly insoluble ionic compounds in water with most cations, Ca2+, could be identified due to that specific cation being one of the few exceptions.9 As a …show more content…
A false positive, an error that arises when the test results are positive even though the sample being studied is not present, could have occurred if the solution was cloudy prior to the addition of K2CrO4 and NH4OH.10 A cloudy solution meant that there was a possibility of contamination where remnants of precipitation that were examined in Part A still remained. These remnants, which could have held lead or silver would have posed a problem, especially if lead was suspended in the cloudy liquid, since Pb2+, like Ba2+, can react with K2CrO4, to form yellow precipitate. The consequence to this similarity would have resulted in a potential false positive with the cation in this step to be incorrectly identified as Ba2+ when it was actually mistaken for
The purpose for this experiment was to determine why it was not possible to obtain a high percent yield when Calcium Nitrate Ca(〖NO_3)〗_2 with a concentration of 0.101 M was mixed with Potassium Iodate KIO_3 with concentration of 0.100 M at varying volumes yielding Calcium Iodate precipitate and Potassium Nitrate. Filtration was used to filter the precipitates of the solutions. The percent yield for solution 1 was 87.7%, and the percent yield for solution 2 was 70.8%. It was not possible to obtain a high percent yield because Calcium Iodate is not completely soluble and some of the precipitates might have been rinsed back to the filtrates when ethanol was used to remove water molecules in the precipitate.
At this point the identity of the unknown compound was hypothesized to be calcium nitrate. In order to test this hypothesis, both the unknown compound and known compound were reacted with five different compounds and the results of those reactions were compared. It was important to compare the known and unknown compounds quantitatively as well to ensure that they were indeed the same compound. This was accomplished by reacting them both with a third compound which would produce an insoluble salt that could be filte...
The sand is If the water with Alka-Seltzer tablets is stirred during the reaction, then the rates of reactions will increase because the particles will be forced to make contact with each other and... ... middle of paper ... ...results anomalies because they are the outcome of dissociation of calcium and magnesium ions,. Evaluation: What is the difference between My results were very reliable, because by looking at my graphs I can see a trend that relates to my scientific background. It is also evident that I have obtained a reliable set of results when I see that.
In this experiment it includes testing water, using Silver Nitrate, waying out salt, and using lamps. When Starting before pouring your water test the water with silver nitrate to make sure it has not been contaminated.
Solid A was identified to be sodium chloride, solid B was identified to be sucrose, and Solid C was identified to be corn starch. Within the Information Chart – Mystery White Solid Lab there are results that distinguishes itself from the other 4 experimental results within each test. Such as: the high conductivity and high melting point of sodium chloride, and the iodine reaction of corn starch. Solid A is an ionic compound due to its high melting point and high electrical conductivity (7), within the Information Chart – Mystery White Solid Lab there is only one ionic compound which is sodium chloride, with the test results of Solid A, it can be concluded that is a sodium chloride. Solid B was identified as sucrose due to its low electrical
Possible errors include leaving in the test strips for too long, draining too much water into the aquatic chamber (overfilling/watering), and inverting the tubes for a shorter amount of time than required. Although there are many possible human errors that could be committed in this lab, it is important to note that the tools used for water testing could be expired and could therefore not work as well at detecting the proper levels for dissolved oxygen, pH, and nitrate.
The purpose of this experiment is to use our knowledge from previous experiments to determine the theoretical, actual, and percent yields of the lead chromate from the reaction of solutions of potassium chromate and lead nitrate (Lab Guide pg. 83).
The experiment was mostly successful because the results were as they were referred on the table. The directions were followed completely as was listed on the board. The instructions were easy enough to follow and perform. There was a list of five tests that were to be done. The indole test was easy to perform and there was no color change on the card. The second test was the Citrate test and the results turned a beautiful blue color in the tube, which showed the results were positive. The Methyl red test was a yellow orange color, which was a negative result. If it was positive it would have turned red color. The Voges Proskauer test resulted in a beige color, which was also showed negative. When looking up the organism E. aerogenes it listed
carbonate and hydrochloric acid,. I will look at the various factors. affecting the reaction and select one variable to change, while the others keep constant in order to carry out a detailed investigation. Formulae = ==
Regarding, the copper and sodium chloride, no visible change occurred after 5 minutes had passed. The copper metal remained at the bottom of the test tube undeterred by the NaCl. There may not have been a reaction because copper is lower on the reactivity series than sodium.
In the experiment, there was a very obvious pattern and many effects on the metals that did react with the acid.
HYPOTHESIS: Once I pour the baking soda solution on the silver it will remove the tarnish from the silver because aluminum is a more active metal than silver causing the silver sulfide to bond to the aluminum.
Refer to Chemistry Lab # 2 – Investigating Changes. No changes have been made in this experiment. Methods = == ==
...se due to the acidic environment. The BOD result will be less than it should be. The pH level should be monitored as well as the temperature. [4]