Analysis : The Unknown Metal Carbonate

either barium (Ba 2+ ) or calcium (Ca 2+ ). Part C consisted of a series of cation flame tests using metal

Your mass precision should be reported to a thousandth of a gram, i.e. 0.302. (Use 3 significant figures.)

12. Determine the percent error using the equation and knowing that the actual specific heat of lead is 0.130 J/g(oC): (10 points)

Though the experiment was carried out smoothly, errors may have occurred that led to an actual mass of 4.166 g for the crude chalcone. After the

Based the data collected, the identity of the unknown #42 is lithium chloride. Because the unknown compound produced a bright red pinkish flame, shown in Table 1, the possible cations based on the CRC Handbook were lithium or strontium 1.The known 1M lithium chloride also produced the same colored flame as the unknown, suggesting that the unknown compound has lithium. Since lithium produces no precipitate with the compounds in Table 2 and strontium produces a precipitate with the same compounds, the observations in Table 2 indicate that the unknown’s cation is lithium 4. Using the solubility table, process of elimination, and the results in Table 3 the possible anions for the unknown compound were chloride and bromide4. The production of precipitate

Then we took 8.35mL of salt water and put it in the evaporating dish which we placed over a Bunsen burner until all the water was dried out. The mass of the evaporating dish with the solid was 83.39g which means the mass of the sodium chloride was 0.622g. Next we took the mass and divided it by the volume of the solution which was 8.35mL and got 0.074 as the original concentration. To the get molarity of the salt solution we had to divide the concentration by the mass of the sodium chloride and then multiply by 1000mL to get 1.3M of salt solution. Final thing we had to do was determine the number ions present in 8.35mL so we took 1.3 moles of NaCl and divided it by 1000mL then multiplied by 8.5mL to get 0.01105 number of Na ions and Cl. The data was as I expected for part A because I followed step by step instructions on how to convert from grams to moles and moles to number of molecules and for part B my answer of 1.3 molarity of salt solution matched with key provided on LoudCloud.

The errors in the lab which could best explain the slight disparity between the measure of the experimental and theoretical masses would be pouring the limiting reagent into the excess reagent, and the inability to completely gather the precipitate into the filter paper. However, since copper(II) sulfate was present on our the filter paper, it would add to the mass, therefore, the mass lost would have to be slightly greater than that gained as to create the slight disparity between the experimental and theoretical masses. Stoichiometric predictions are valid as long as errors in the experimental trial are taken into consideration. Furthermore, the experimental mass could be more similar to stoichiometric predictions if the excess reagent was poured into the limiting reagent, and if more than one trial were conducted. Additionally, the results of this lab, as well as any other lab, would be more thorough and conclusive if it was conducted more

With the mass of oxygen found, 0.02 grams, the percent compositions of magnesium and oxygen can be found by dividing their masses by the total mass of the new compound:

The crude and pure yields of the unknown acid were 0.137 g and 0.049 g, respectively.

After heating the extracted solution in the 50ml beaker for weighing purposes, some of the water might condense back into the liquid state (in the form droplets), thereby leading to an increase in the calculated weight of Potassium chloride. Therefore

The purpose of this lab was to become familiar with the three different balances and two different methods used to find the weight and mass of chemicals and compounds in the ChemLab program. The lab was performed by using three different types of balances, and the direct weighing and weighing by difference methods.

The volume of carbon dioxide gas produced from a reaction was measured in order to determine what carbonate sample was used. A gas assembly apparatus was used to capture the gas from a reaction between an unknown carbonate and 6M hydrochloric acid; three trials were performed. The mass of the unknown carbonate was determined, and the reaction occurred in a test tube. The volume of gas produced by the reaction was measured, and the partial pressure of carbon dioxide was calculated after the partial pressure of water vapor was determined using Dalton’s Law of Partial Pressures. The percent mass of carbon dioxide gas was then calculated, and the average mass percent was compared to the table of known carbonates. It was concluded that the unknown carbonate sample used in the reaction was magnesium carbonate.

The main objective of this experiment is to carry out qualitative analysis to identify metal cations in unknown solution 1.

5. Equivalence Point: 24% error, Gravimetric determination: 17% error. The gravimetric determination was more accurate because an exact amount of precipitate was formed.

4g of Na CO x 1 mol of Na CO 4g of CaCl x 1mol of CaCl