Possible margin of errors
Possible margin of errors
1. Clean, rinse, and fill a buret with NaOH solution just as you did in last week's experiment. Record the molarity of the NaOH and the initial NaOH volume reading from the buret (+0.02 mL).…
To calculate the percent composition of a component in a compound you have to find the molar mass of the compound by adding up the masses of each atom…
To begin the experiment, the unknown needs to be determined as an acid or a base by using litmus paper or a pH strip. For the rest of the experiment, if the substance is being handled, gloves and goggles must be worn. Use a clean and dry Erlenmeyer flask and weigh it. Then, some of the unknown will be measured and poured into the flask. Also way the flask and the unknown.…
Before 1982 the US penny was made of pure copper. Because of the high cost of copper, the US government changed the composition of the penny. As of 1982, pennies have been made of mostly zinc, with a thin copper layer on the outside. The first step in finding the % of copper is to make solution out of the penny. In other words “liquefy” the penny. To differentiate between the copper and zinc; zinc is clear and copper turns blue. During this lab, we will be making several standard solutions of this penny solution. To find out each solutions concentration, we will find its molarity by using the formula:…
Undoped and Ce doped ZnO thin films were prepared by the sol-gel process. Zinc acetate dehydrate was dissolved in a mixture of absolute ethanol and monoethanolamine (MEA) yielding to a precursor concentration of 0.4 M .The MEA to zinc acetate molar ratio was set to 1. For doped films, cerium nitrate was added to the mixture with an atomic percentage fixed at 0.1, 0.3, 0.5, 0.7, and 0.9 at.% Ce, respectively.…
Start off by weighing two paracetamol tablets using some accurate scales. Record the mass down (1.15g). This had to be as accurate and precise as we could get it so we had the correct weight to start the experiment. Without this then the results we found at the end would not be accurate. A problem that could be faced with this is that the scales may not have been fully set to zero. Also it takes time for it to fully reach its weight on the reading so you may move them too quick before the right weight has been set.…
Objective: The purpose of this experiment is to determine the percent composition of pennies using oxidation-reduction and double displacement reactions as well as titration techniques. We will take a post 1982 penny and place in a strong acid dissolving the zinc core and leaving behind the copper coating. We will figure out the percent composition from the mass of copper and zinc using titration and precipitation.…
In trial one the percent mass of NaNO2 in the unknown mixture was 59.30%. In trial two, the percent mass of NaNO2 was 63.47%. Lastly in trial three, it was determined that the percent mass of NaNO2 was 60.11%. Based on these results the average percent mass of the NaNO2 was 60.96% with a standard deviation of 2.209. Lastly, the percent relative standard deviation was determined to be 3.623. Thus, the percent precision was found to be 96.38% suggesting that the process used to determine these results was fairly consistent.…
moles of HCl that is actually needed. To determine the percent zinc in the penny, the…
zinc and the hydrochloric acid combined to create zinc chloride. You know the mass of zinc used, and the mass of zinc chloride…
Lab #18 Stoichiometry In this lab, we reacted aluminum foil with a copper chloride solution, and determined the amount of metal that should be produced, given the amount of aluminum used. First, we obtained a piece of aluminum with a mass of 0.809 g, and reacted it with 100 mL of Copper II Chloride, after heating the solution. Then, we filtered out the copper separated in the reaction using filter paper, massing 0.751 g. Once all the solution was filtered, we massed the new filter paper filled with copper, after letting it dry overnight. The mass of the filter paper with the copper was 3.450 g, making the mass of just the copper 2.699 g. This closely compares to the accepted mass of copper for this reaction of 2.88 g. Finally, we found the…
4) Difference in answer could be the different initial masses of zinc, how accurate on measuring the hydrochloric acid, and calculation errors.…
The percent of any compound or element can be found by using a certain formula. This formula is: % of element = Mass of element or compound/Total mass of compound x100. In order to use this formula the mass of the water and the total mass of the hydrate had to be found. The lab workers…
Synthesis and the determination of empirical formulas are two extremely important parts of chemistry. In this experiment, you will synthesize zinc iodide and determine its empirical formula. The molecular formula gives the actual number of atoms of each element in the molecule and the empirical formula gives the lowest whole number ratio of the atoms in the molecule. For instance, the molecular formula of glucose is C6H12O6 and its empirical formula is CH2O. For some molecules such as water, the empirical and molecular formulas are the same. One of the common techniques used to help determine the identity of a substance involves combustion of very small amounts of the substance. By measuring the amounts of water, carbon dioxide, and other gases produced, it is possible to determine the percentage by mass of each element in the compound. From the percentages, it is possible to calculate the empirical formula of the compound. Suppose, for example, that the combustion experiment for a compound that contains carbon, hydrogen, and oxygen gives the compositions as 40.00% carbon, 6.71% hydrogen, and 53.29% oxygen by mass. The goal is to convert mass percentages to mole or atom ratios. Whenever dealing with percentages in a calculation of this type, one of the easiest ways to proceed is to assume that you have 100 g of the substance. Thus 100 g of the substance contains 40.00 g of carbon, 6.71 g of hydrogen and 53.29 g of oxygen. As is common for many chemical calculations, the calculation of the number of moles is one of the first steps. Thinking ahead, once the number of moles is known, the ratio of moles is easily calculated.…
Nest two similar foam cups into a calorimeter. Make sure they are clean and dry Using a paper punch, make two small holes in a plastic lid that fits tightly over the foam cups. Make one hole in the center and one off to the side. Retrieve the stirring wire and thermometer. With a 50mL graduated cylinder, measure out 50mL of distilled water into a clean, dry 150mL beaker and heat on a hot plate to 70°C-80°C by slowly raising the temperature. Stir with a glass rod occasionally to make sure the heating is uniform. Measure 50mL of cold distilled water and place in the calorimeter setup. As the water is heating, also monitor the temperature of the cold water to find when it reaches equilibrium. Record the temperature of the cold water to the nearest 0.2°C. When the water being heated reaches 70°C-80°C, remove from the heat and let it sit on the lab bench, stirring occasionally. Record the temperature of the hot water to the nearest 0.2°C. Quickly, remove the lid from the calorimeter and pour in the hot water. Replace the lid. Stir for 30 seconds, then begin monitoring the temperature of the combined water. Record the highest temperature reached in the calorimeter to the nearest 0.2°C. Calculate the calorimeter constant for your calorimeter. Repeat the experiment twice more and use the mean value of the three determinations.…