1. How do we make use of stoichiometry to determine molecular mass of the origin

ID: 813832 • Letter: 1

Question

1. How do we make use of stoichiometry to determine molecular mass of the original alkai metal carbonate?

2. What is the molecular ratio of the calcium carbonate formed to the original alkali metal carbonate?

3. What would you anticipate as potential sources of error in making this determination?

4.What are the molecular formulas and molar masses of the possible alkali metal carbonates?

5. An unknown metal carbonate was analyzed gravimetrically and yielded the following:

a. Mass of dried M2CO3 1.972g

b. Mass of filter paper 0.598g

c. Mass of filter paper + CaCO3 2.436g

d. Mass of CaCO3 __________ (c-b)

e. Moles of CaCO3 __________

f. Moles of M2CO3 __________(=e)

g. Molar mass of M2CO3 __________(a/f)

h. Identity of M2CO3 ___________

i. Percent error ______________

a. Mass of dried M2CO3 = 1.972g

b. Mass of filter paper = 0.598g

c. Mass of filter paper + CaCO3 = 2.436g

d. Mass of CaCO3 = 1.865

e. Moles of CaCO3 = mass / mol wt = 1.865 / 100 = 0.01865

f. Moles of M2CO3 = 0.01865(=e)

g. Molar mass of M2CO3 1.972 / 0.01865= 107.29 (a/f)

so mass of metal = 105.73 - 60 = 45.73

h. Identity of M2CO3 = Na2CO3

i. Percent error ______________

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