1-The mineral limestone is used to reduce the acidity of soil. Limestone consist
ID: 902481 • Letter: 1
Question
1-The mineral limestone is used to reduce the acidity of soil. Limestone consists primarily of calcium carbonate, CaCO3.Calcium carbonate reacts with hydrochloric acid to from calcium chloride,water,and carbon dioxide. Balance the following equation for this reaction
If an amount of hydrochloric acid containing 3.20*10-2 moles of HCL is needed to react completely with the calcium carbonate in a 2.00 g sample of limestone. what is the per cent by wieght of CaCO3 in the limestone?
2-Pyrolusite is an ore containing MnO2. The metal oMn can be extracted from the ore by reacting it with Al. The equation for the process(known as the thermite reaction)
a-If reaction of 1.89g of Al produces 0.500 mole of Mn,what is the precent yield for the reaction?
b-If 10.50g of MnO2 is allowed to react with 3.00g of Al, what is the maximum number of grams of manganese Mn that can be produced ?
Explanation / Answer
CaCO3+ 2HCL ---> CaCl2+ CO2+ H2O
No of moles of HCl = 3.20*10-2 moles
No of moles of caco3 reacted = 3.20*10-2/2 = 0.016 mole
molarmass of CaCO3 = 100.0869 g/mol
mass of CaCO3 = 0.016*100.0869 = 1.6014 grams
mass percentage of CaCO3 in stone = 1.6014/2*100 = 80.07%
2.
3MnO2+4Al ----> 2Al2O3+3Mn
a.
No of moles of Al = 1.89/27 = 0.07 mole
from the reaction
3 mole Mno2 = 4 mole Al = 3 mole Mn
No of moles of Mn PRODUCES = 0.07*3/4 = 0.0525 mole
precent yield for the reaction = 0.5/0.0525*100 = 952%
b. No of moles of MnO2 = 10.5/86.9368 = 0.121 mole
No of moles of Al = 3/27 = 0.11 mole
limiting reagent = MnO2
No of moles Of Mn = 0.11*3/4 = 0.0825 mole.
mass of Mn = 0.0825*55 = 4.5375 grams
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