if we did not use an excess of the BaCl2 solution it would decrease the mass percentage of sulfate in the unknown sample.
The net precipitation equation would be.
Ba2+(aq) + SO42-(aq) → BaSO4(s)
If BaCl2 (Ba2+) is not taken in excess then the precipitation would not be completed as some of the sulfate ions would still be remaining in the solution. This would decrease the mass percentage of sulfate in the unknown sample.
If some tiny pieces of filter paper still remained mixed with the precipitate(BaSO4) then the mass of sulfate would increase and it gives a high mass percentage of the sulfate.
mass percentage of sulfate = (mass of sulfate/mass of sample)*100
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The second answer is not a characteristic because compounds don’t vary from sample to sample. For example NaCl (table salt) is indistinguishable from sample to sample.
I'm not positive, but I believe it would be one near the Rocky Mountains.
The energy that was released by the candy is calculates using the below formula
Q=Mc delta T
Q= heat energy
m= mass (500g)
C= specific heat capacity) = 4.18 j/g/c
delta t =change in temperature = 25- 21 = 4 c
Q= 500 g x 4.18 j/g/c x 4c = 8360 j
The answer is 27.92g . working is shown in the picture above.
