Mary and Joe, two researchers, weighed out 2.00 g each of five solid compounds i
ID: 544713 • Letter: M
Question
Mary and Joe, two researchers, weighed out 2.00 g each of five solid compounds into sample vials to use later in an experiment. The five compounds were: .barium chloride magnesium nitrate . silver nitrate sodium carbonate sodium hydrogen sulfate Unfortunately, they had only numbered the vials 1-5, without identifying which number belonged to which compound, and all of the samples looked alike (they were all colourless solids). Rather than weighing out the samples again, the two researchers decided to chemically identify the compounds, But Mary and Joe argued about what strategy to use. Each researcher argued that his/her proposed strategy was the correct one, and that using the other strategy would misidentify some of the compounds. So they decided to try both strategies independently, and then compare results. Will Mary and Joe come up with the same result using different strategies, or is one of them making a fatal error? Let's find out. In this problem we will walk through each of Mary's and Joe's strategy, and you will predict the outcome of each test based on knowledge you gained during your practicals this semester. As you answer these questions, take notes of the identities of the compounds in each numbered tube as determined by Mary and Joe (a table might help). We will compare them at the end. You will definitely need the "CVB101 Constants and information for quizzes and exams" for this! Here's what Joe tried First Joe dissolved each solid as pairs in water in every possible combination. The solution containing the compounds from tube 2 and tube 4 effervesced (bubbled) From this result, Joe knew which two compounds these must be, although he did not know which compound belonged to which tube Which two compounds must be in tubes 2 and 4? (Note, this is a multiple answer question. Please tick all answers that apply.) barium chloride magnesium nitrate silver nitrate sodium carbonate sodium hydrogen sulfateExplanation / Answer
1. You must look for the reaction that may cause CO2 this is a result from an effervescent reaction so sodium carbonate Na2CO3 now let´s find the one that might have caused the reaction.
Na2CO3 with BaCl2 will produce BaCO3 which is a precipitate and NaCl which is a salt this certainly does not form buubles.
The Mg(NO3)2 will create MgCO3 which is a precipitate and it won´t create bubbles
AgNO3 won´t create bubbles
The NaHSO4 must be the one, the reaction is
2NaHSO4 + Na2CO3 ---> 2Na2SO4 + CO2 + H2O
2. compound in test tube must be Na2CO3
BaCl2 will produc BaCO3 which will precipitate
with Mg(NO3)2 you will crate MgCO3 which will precipitate
with AgNO3 you will create Ag2CO3 which will precipitate
3. In test tube 4 must be NaHSO4 (sodium hydrogen sulfate)
4. If you mix NaHSO4 with the other compounds you will create sulphates
sulphates BaSO4, Ag2SO4 and MgSO4
BaSO4 is not soluble so it will precipitate
MgSO4 is soluble
Ag2SO4 is slightly soluble, it has a low ksp but if the concentration is low it may not precipitate
So we can be sure that BaCl2 is in the tube
5. If you mix BaCl2 with AgNO3 you will produce AgCl, this salt will precipitate so we can say that we have AgNO3 in that tube .
something similary happens with MgNO3, it will create MgCl2 this is a soluble salt.