Recent questions in Analytical Chemistry

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A chemistry student is given an unknown compound and asked to identify it using mass spectrometry. The mass spectrum of the compound shows a molecular ion peak at m/z 150, a base peak at m/z 135, and a few smaller peaks at m/z 91, 77, and 65. What is the possible molecular formula of the unknown compound?

asked Jan 22 in Analytical Chemistry by Lavonda96B02 (2.3k points)

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1 answer 115 views

A chemistry student is given a sample of an unknown salt consisting of a mixture of two compounds. The student is asked to determine the percentage composition of each compound in the salt using mass balance calculations. The total mass of the sample is 10 grams, and after performing careful analysis, the student obtains the following data: One compound has a molar mass of 80 g/mol and comprises 60% of the total mass of the salt. The other compound has a molar mass of 120 g/mol and comprises 40% of the total mass of the salt. What are the percentage compositions of each compound in the salt?

asked Jan 22 in Analytical Chemistry by RosieBloom03 (1.8k points)

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1 answer 110 views

A chemistry student is given a sample of an unknown compound and is asked to determine its molecular formula and possible functional groups using mass spectrometry. The mass spectrum of the compound shows a molecular ion peak at m/z 158 and three intense fragmentation peaks at m/z 132, 104, and 77. Using this information, determine the molecular formula and possible functional groups of the unknown compound.

asked Jan 22 in Analytical Chemistry by GlenSchramm (1.7k points)

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1 answer 68 views

A chemistry student is given a sample of a solution containing a known amount of sodium chloride (NaCl) dissolved in water. The student needs to determine the concentration of the NaCl in the solution, using mass balance calculations. The student has access to a balance and other necessary laboratory equipment. What is the concentration of NaCl in the solution given to the student? How much NaCl is present in the solution, and how much water was used to dissolve it?

asked Jan 22 in Analytical Chemistry by CharleyPrior (1.8k points)

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1 answer 108 views

A chemistry student is given a sample of a compound containing sulfur, oxygen, and carbon. The student needs to determine the mass percentages of each element in the compound using mass balance calculations. The sample has a total mass of 5.00 grams, and the student devises an experiment to isolate each of the three elements by chemical reactions, and the mass of each element is recorded as follows: 1.20 g sulfur, 1.80 g oxygen, and 2.00 g carbon. What are the mass percentages of sulfur, oxygen, and carbon in the compound?

asked Jan 22 in Analytical Chemistry by RosettaMcinn (1.7k points)

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1 answer 18 views

A chemistry student is given a 25 mL sample of a solution containing an unknown amount of sodium chloride. After adding excess silver nitrate solution to the sample, the student records the mass of the resulting precipitate to be 2.655 grams. Using mass balance calculations, determine the mass percentage of sodium chloride in the original solution.

asked Jan 22 in Analytical Chemistry by AlisiaBarwel (2.1k points)

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1 answer 100 views

A chemistry student is given a 10 mL sample of a solution containing chloride ions and sulfate ions, and is asked to determine the mass of each ion present in the sample. The student knows that the total mass of the solution is 12.25 g, and that the density of the solution is 1.225 g/mL. The student also knows that the mass percent of chloride ions in the solution is 5%, and the mass percent of sulfate ions is 10%. Using mass balance calculations, what is the mass of chloride ions and sulfate ions present in the sample?

asked Jan 22 in Analytical Chemistry by KaiRazo33412 (1.9k points)

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1 answer 71 views

A chemistry student is asked to determine the concentration of copper ions in a 500 mL solution of copper sulfate. The student has access to a balance, a pipette, and standard solutions of sodium hydroxide and sulfuric acid. Using the mass balance calculations, what is the concentration of copper ions in the solution?

asked Jan 22 in Analytical Chemistry by Precious09K0 (2.0k points)

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1 answer 70 views

A chemistry student is asked to determine the concentration of a particular compound in a sample of drinking water. The student collects a 100 mL water sample and adds a known amount of a standard solution containing the compound. After allowing the solution to equilibrate, the student measures the concentration of the compound in the new solution using a spectrophotometer, to be 0.0125 M. Assuming mass balance, calculate the concentration of the compound in the original drinking water sample.

asked Jan 22 in Analytical Chemistry by Kurt09Q6154 (1.9k points)

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1 answer 118 views

A chemistry student has a sample of an unknown compound containing carbon, hydrogen, and oxygen. The mass of the sample is 2.50 g. After combustion, the student finds that 1.80 g of carbon dioxide, 0.75 g of water, and 0.20 g of oxygen are produced. Using mass balance calculations, determine the empirical formula of the unknown compound.

asked Jan 22 in Analytical Chemistry by Shelia708886 (2.1k points)

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1 answer 114 views

A chemistry laboratory is provided with a 10 mL solution containing a mixture of sodium chloride and potassium chloride. After adding an excess of silver nitrate, it has been observed that 0.476 grams of AgCl precipitate out. Determine the mass of each component (NaCl and KCl) in the original solution using mass balance calculations.

asked Jan 22 in Analytical Chemistry by JEAMolly3713 (2.3k points)

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1 answer 98 views

A chemist has a sample of an unknown compound with a mass of 5.00 g. After analyzing the sample, the following results were obtained: 0.50 g of oxygen, 1.25 g of carbon, and 3.25 g of hydrogen. Calculate the molecular formula of the unknown compound using mass balance calculations.

asked Jan 22 in Analytical Chemistry by KreogMoore5 (6.4k points)

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1 answer 81 views

A chemist analyzed a sample of unknown substance and found that it contains 55% carbon, 9.17% of hydrogen and the rest of the mass is oxygen. What is the percentage by mass of oxygen in the sample?

asked Jan 22 in Analytical Chemistry by GracieGainfo (2.2k points)

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1 answer 75 views

A 5 g sample of a mixture containing sand and salt is dissolved in water. The solution is filtered, and the sand is collected and dried. The dried sand has a mass of 3 g. Using mass balance calculations, determine the percentage of salt in the original mixture.

asked Jan 22 in Analytical Chemistry by PrincessDial (2.0k points)

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1 answer 86 views

A 15.0 g sample of a mixture containing sodium chloride and sodium nitrate is dissolved in water, and then silver nitrate is added until no more precipitation occurs. The mass of the precipitate is found to be 20.4 g. What is the mass percentage of each component in the mixture?

asked Jan 22 in Analytical Chemistry by TommyBarfiel (2.2k points)

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1 answer 92 views

A 5 g sample of a mixture containing sand and salt is dissolved in water. The solution is filtered, and the sand is collected and dried. The dried sand has a mass of 3 g. Using mass balance calculations, determine the percentage of salt in the original mixture.

asked Jan 22 in Analytical Chemistry by TammiTolbert (2.1k points)

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1 answer 93 views

A 15.0 g sample of a mixture containing sodium chloride and sodium nitrate is dissolved in water, and then silver nitrate is added until no more precipitation occurs. The mass of the precipitate is found to be 20.4 g. What is the mass percentage of each component in the mixture?

asked Jan 22 in Analytical Chemistry by AlishaGuy35 (2.5k points)

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