Question

I tried doing the first few but I'm not sure if I'm doing right and I need help with the last few. the last picture is the equation page. thank you!

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,上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)

Answer 1

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