750.0g of water that was just boiled (heated to 100.0/c loses 78.45KJ of heat as it cools.What is the final temperature of water
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Answer:
a) Percentage by mass of carbon: 18.3%
Percentage by mass of hydrogen: 0.77%
b) Percentage by mass of chlorine: 80.37%
c) Molecular formula:
Explanation:
Firstly, the mass of carbon must be determined by using a conversion factor:
The same process is used to calculate the amount of hydrogen:
The percentage by mass of carbon and hydrogen are calculated as follows:
%C= 18.3%
%H=0.77%
From the precipation data it is possible obtain the amount of chlorine present in the compound:
= 0.43g AgCl
Let's calculate the percentage by mass of chlorine:
%Cl== 80.37%
Assuming that we have 100g of the compound, it is possible to determine the number of moles of each element in the compound:
Dividing each of the quantities above by the smallest (0.77mol), the subscripts in a tentative formula would be
≈ 2
≈3
The empirical formula for the compound is:
The mass of this empirical formula is:
mass of C + mass of H + mass of Cl= 24g +1+ 106.35 =131.35g
This mass matches with the molar mass, which means that the supscript in the molecular formula are the same of the empirical one.