Lab Data = kbmI -mbeaker = 61.78 g - mbeaker w / H2O = 119.30g -m volumetric Fla

Question

Lab Data = kbmI -mbeaker = 61.78 g - mbeaker w / H2O = 119.30g -m volumetric Flask = 34.87g - m Nacl = 12.00g -mbeaker w / H2O + Nacl = 131.27 g - m volumetric flask + solution = 90.91 g - BP of distilled water = 95 degree C - BP of solution = 90 degree C BP = boiling point M = mass For each calculation, show detailed work in steps. Find the percent by mass of salt in the solution. Find the molality of salt in the solution. Find the density of solution. Find the molarity of salt in the solution. Find the mole fraction of water in the solution. What was the difference in measured boiling points of water and solution? What is the expected Delta T from calculation? Are these values close?

Explanation / Answer

1) percent by mass of salt in solution = mass of salt/(mass of solution)

= 100*12/(119.3-61.78+12)

= 17.26 percent by mass

2) molality = moles of salt/mass of solvent (in kg)

= 1000*(12/58.44)/(119.30-61.78) = 3.57 m

3) density = mass of matter/volume [considering volume of salt to be negligible]

=(131.27-61.78)/(119.30-61.78) = 1.20 g/cm3

4)Molarity of salt = number of moles of salt/volume of solution = 1.2*1000*(12/58.44)/(90.91-34.84)

=4.394 M

5)mole fraction of water = moles of water/(moles of salt+moles of water)

= ((119.30-61.78)/18.01)/((12/58.44)+((119.3-61.78)/18.01))

=0.93

6)Difference in measured BP and solution = 5 degree celcius

calulated, delta(T) =0.51*2*3.54 = 3.61 degree celcius

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