Nov 23, 2015 Experiment 5 Advance Study Assignment: Identification of a Compound
ID: 918765 • Letter: N
Question
Nov 23, 2015 Experiment 5 Advance Study Assignment: Identification of a Compound by Mass Relationships 1. A student attempted to identify an unknown compound by the method used in this experiment. She found that when she heated a sample weighing 0.5032 g, the mass dropped to 0.2663 g. When the product was converted to a chloride, the mass went back up, to 0.3747 g .7479 Is the sample a carbonate? Yes) no (Circle one) a. Please provide your reasoning below. It xems to be ecau wnun nuated, the cosoonote Gives ope an oida and (oa) wnich redwcs h mass, bur wnan convert ed to ntoridk, inweaces bece b. What are the two compounds that might be in the unknown? Write the balanced chemical equation for the overall reaction that occurs when each of these two original compounds is converted to a chloride. If the compound is a hydrogen carbonate, use the sum of Reactions 1 and 2. If the sample is a carbonate, use Reaction 2. Write the equation for a sodium c. d. How many moles of the chloride salt would be produced from one mole of the oniginal compound? e. How many grams of the chloride salt would be produced from one molar mass of the original Molar masses: NaHco, 8401 g/mol Na.co,05.99 g/mol Naasa.fddgrnol KHCO, 100.r8 g/mol K,CO, 138.21 g/mol KCI 74,55s/mol If a sodium salt, 0.5032 g original compound- g chloride If a potassium sal, g original compound g chloride (continued on following page)Explanation / Answer
1a. The answer is NO.
The sample is not a carbonate, but a hydrogen carbonate. We found an important decrease of mass when heating the sample.
( Read the first page)..
1b. NaHCO3 or KHCO3
( Read the first page)..
1c.
2NaHCO3 = Na2CO3 + H2O + CO2
Na2CO3 + H+ + Cl- = 2NaCl + H2O + CO2
…………………………………………………
2NaHCO3 + 2H+ +2Cl- = 2NaCl +2H2O + 2CO2
Replace Na by K and write an other set of equations.
1d.
2NaHCO3 + 2H+ +2Cl- = 2NaCl +2H2O + 2CO2
2 mol…………………………2mol
1 mol…………………………x
X= 1 mol (the answer)
1e.
The original salt was NaHCO3 or KHCO3
If a Na salt,
84.01g NaHCO3 produces…………………58.44 gNaCl (if no water loss at heating)
0.5032 g…………………………………….x
X= 0.3500 g NaCl
If a K salt,
100.12 g KHCO3 produces…………………74.55 g KCl (if no water loss at heating)
0.5032 g…………………………………….x
X= 0.3747 g KCl (this is the value you have as experimental data)
1f
Theoretical Q for NaHCO3
Q = (0.3500- 0.5032)/0.5032 = …
Theoretical Q for NaKCO3
Q = (0.3747- 0.5032)/0.5032 = …
1g
Experimental Q
Q = (0.3747- 0.5032)/0.5032 = …
1h. KHCO3
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.