1. A 4.27g sample of a laboratory solution contains 1.45g of acid. What is the c
ID: 909777 • Letter: 1
Question
1. A 4.27g sample of a laboratory solution contains 1.45g of acid. What is the concentration of the solution as a mass percentage? The figure below is a heat curve for an unknown outerspace substance discovered by the Mars rover. By understanding the heal curve, scientists can make inferences about the composition of the planet What is the temperature of fusion, T fusion and vaporization, T vapor, for this unknown substance? Note that the units we graded For a sample of 54.6 g of this substance with a specific heat or 52.0 J/kg degree C, how much heat is added to the substance if the temperature is to change from 180.0 degree C to 220.0 degree C? Here are the solubilities of a particular solute at two different temperatures. Suppose that you hove made a saturated solution of this solute using 60.0 g of water at 20.0 degree C. How much more solute can you add it the temperature n increased to 30.0 degree C?Explanation / Answer
1) Concentration (as mass %) = (1.45 / 4.27) x 100 = 33.96 %
2) T (fusion) = 80 degree C
T (vapor) = 280 degree C
Q = m Cp (T2 - T1)
=> Q = (54.6 / 1000) x 52 x (220 - 180) = 113.6 J
3) Mass of solute in 100 g water (for saturated solution) at 20 degree C = 36.9 g
=> Mass of solute in 60 g water (for saturated solution) at 20 degree C = 36.9 x 60 / 100 g = 22.14 g
Mass of solute in 100 g water (for saturated solution) at 30 degree C = 84.5 g
=> Mass of solute in 60 g water (for saturated solution) at 30 degree C = 84.5 x 60 / 100 g = 50.7 g
=> Solute that can be added = 50.7 - 22.14 = 28.56 g
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