13. What is the concentration of a 0.500 M NaCl solution in terms f a. mass perc
ID: 716878 • Letter: 1
Question
13. What is the concentration of a 0.500 M NaCl solution in terms f a. mass percent b. mole fraction (assume the density of the solution is 1.00 g/mL, show your work) 14. Which aqueous solution would have the highest boiling point? a. 0.025 m CaCl b. 0.030 m NaCl c. 0.100 m glucose (C&H1206) d. 0.030 m Fe(NO)s 15. Which aqueous solution would have the highest melting point? a. 0.025 m CaCl2 b. 0.030 m NaCl c. 0.100 m glucose (CsH1206) d. 0.030 m Fe(NO)s 16. The vapor pressure of pure ethanol at 25°C is 59mM Hg. What is the vapor pressure of a solution composed of 4.630 g of tannic acid (Cr&Hs20%, molar mass 1701.19 g/mol) is dissolved in 50.00 mL of ethanol (C2HsO)? Show your work. 17. The osmotic pressure of an aqueous solution containing an g of an unknown peptide is 0.6117 atm. To make the solution, 0.1054 g of the protein was dissolved in enough water to make 2.000 mL. What is the molar mass of this peptide? Show your work.Explanation / Answer
13) concentration of NaCl = 0.5 M
a) Molarity(M) = %bymass*d*10/Mwt
%bymass = x
d = density = 1.00 g/ml
M.wt = molarmass of NaCl = 58.5 g/mol
0.5 = x*1*10/58.5
%bymass = x = 2.925%
b) 0.5 mol NaCl present in 1 L solution.
molefraction of NaCl = mol of NaCl/total moles
total moles = moles of NaCl + moles of water
moles of water = (1000-0.5*58.5)/18 = 53.93 mol
molefraction of NaCl = 0.5/(53.93+0.5)
= 0.0092
14) greater the no of ions, greater the boiling point of solution.
answer: d.0.030 m Fe(NO3)3
15) greater the no of ions, LOWEST the freezing point of solution.
answer: b.0.03 m NaCl
16)
raoults law
P0-P/P0 = i*Xsolute
P0-P/P0 = n2 / n1+n2
i = vanthoffs factor of solute(tannic acid) = 1
P = vapor pressure of solution = ?
p0 = vapor pressure of pure ethanol at this temperature = 59 mmhg
n1 = no of mol of solvent = (50*0.789/46) = 0.858 mol
n2 = no of mol of solute particles(KCl) = (4.63/1701.19) = 0.00272 mol
(59-x)/59 = 1*(0.00272/(0.00272+0.858))
P = vapor pressure of solution = 58.8 mmhg
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