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Osmotic Pressure and Equilibrium constant

  • Thread starter WK95
  • Start date
  • #1
139
1

Homework Statement


An aqueous solution contains 0.84 g/L of an organic detergent. The osmotic pressure of this solution is 54.4 torr, at 25°C. What is the molar mass (in g/mol) of this detergent?

Homework Equations


##pi=MRT##
##R=0.08206L*atm/(mol*K)##

The Attempt at a Solution


##pi=MRT##
##M=pi/(RT)##
##M=(54.4 torr * 1 atm/760 torr)/(0.08206L*atm/(mol*K))(298.15 K)##
This is wrong but I;m not sure why and how to get the right asnwer.

Homework Statement


What is the equilibrium constant expression for the following reaction:

PtCl42−(aq)↔Pt2+(aq) + 4Cl−(aq)

Choose from the list below and enter the letters alphabetical order. (e.g. For an equilibrium constant of [Cl-]4eq[Pt2+]eq enter AH.)

A) [Pt2+]eq E) [Cl-]-1eq I) [PtCl42-]4eq
B) [Cl-]eq F) [PtCl42-]-1eq J) [Pt2+]-4eq
C) [PtCl42-]eq G) [Pt2+]4eq K) [Cl-]-4eq
D) [Pt2+]-1eq H) [Cl-]4eq L) [PtCl42-]-4eq



Homework Equations



The Attempt at a Solution

 

Answers and Replies

  • #2
3,812
92

Homework Statement


An aqueous solution contains 0.84 g/L of an organic detergent. The osmotic pressure of this solution is 54.4 torr, at 25°C. What is the molar mass (in g/mol) of this detergent?

Homework Equations


##pi=MRT##
##R=0.08206L*atm/(mol*K)##

The Attempt at a Solution


##pi=MRT##
##M=pi/(RT)##
##M=(54.4 torr * 1 atm/760 torr)/(0.08206L*atm/(mol*K))(298.15 K)##
This is wrong but I;m not sure why and how to get the right asnwer.

Homework Statement


What is the equilibrium constant expression for the following reaction:

PtCl42−(aq)↔Pt2+(aq) + 4Cl−(aq)

Choose from the list below and enter the letters alphabetical order. (e.g. For an equilibrium constant of [Cl-]4eq[Pt2+]eq enter AH.)

A) [Pt2+]eq E) [Cl-]-1eq I) [PtCl42-]4eq
B) [Cl-]eq F) [PtCl42-]-1eq J) [Pt2+]-4eq
C) [PtCl42-]eq G) [Pt2+]4eq K) [Cl-]-4eq
D) [Pt2+]-1eq H) [Cl-]4eq L) [PtCl42-]-4eq



Homework Equations



The Attempt at a Solution

It's quite difficult to follow what you have done here.

For the first part, please define the variables used.

For the second part, use the subscript and superscript tags or LaTeX to format your working.
 
  • #3
20,235
4,265
The osmotic pressure satisfies the same equation as the ideal gas law. In your problem solution, you need to use the density of the detergent.

[tex]ρ=\frac{p_iM}{RT}[/tex]

You need to solve for M.
 

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