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Answer:
6.82g
0.59moles
Explanation:
1. What is the mass sample of 0.0500 moles of zinc chloride ?
Given parameters:
Number of moles ZnCl₂ = 0.05moles
Unknown:
Mass of the sample = ?
Solution:
To find the mass of a substance using the number of moles, it would be pertinent to understand what mole is.
A mole is a substance that contains the avogadro's number of particles.
It relates to the mass using the expression below;
Mass of a substance = number of moles x molar mass
Molar mass of ZnCl₂;
Atomic mass of Zn = 65.4g/mol
Cl = 35.5g/mol
Molar mass = 65.4 + 2(35.5) = 136.4g/mole
Mass of a substance = 0.05 x 136.4 = 6.82g
2. How many moles of potassium sulfide are in a 65.50g sample?
Given parameters:
Mass of K₂S = 65.5g
Unknown:
Number of moles = ?
Solution:
The number of moles of any substance is related to mass using the expression below;
Number of moles =
Molar mass of K₂S = 2(39) + 32 = 110g/mol
Number of moles = = 0.59moles
Answer:
92.04%
Explanation:
Given:
Mass of CO₂ obtained = 53.0 grams
Mass of calcium carbonate heated = 1.31 grams
Now,
the molar mass of the calcium carbonate = 100.08 grams
The number of moles heated in the problem = Mass / Molar mass
= (1.31 grams) / (100.08 grams/moles)
= 0.013088 moles
now,
1 mol of calcium carbonate yields 1 mol of CO₂
thus,
0.013088 moles of calcium carbonate will yield = 0.013088 mol of CO₂
now,
Theoretical mass of 0.013088 moles of CO₂ will be
= Number of moles × Molar mass of CO₂
= 0.013088 × 44 = 0.5758 grams
Thus, the percent yield for this reaction =
or
the percent yield for this reaction =
or
the percent yield for this reaction = 92.04%