Physical Chemistry (dissolution of a substance)

To find the freezing point depression, use the equation \DeltaT = K_f\cdot m, where \DeltaT is the change in temperature, K_f is the freezing point constant, and m is the molality of the solute. To find the molality, you need to determine the number of moles of the solute first. Use the equation m = n_solute / n_solvent, where n_solute is the number of moles of solute and n_solvent is the number of moles of solvent. To find the number of moles of the solute, use the equation n_solute = m_solute \cdot w_solute / M_solute, where m_solute is the mass of the
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Homework Statement


The dissolution of 5.25 g of a substance in 565 g of benzene at 298 K raises the boiling
point by 0.625°C. Note that Kf = 5.12 K kg mol-1, and Kb = 2.53 K kg mol-1, and the density of benzene is 876.6 kg m-3. Calculate the freezing point depression, the ratio of the vapor pressure above the solution to that of the pure solvent, the osmotic pressure,
and the molecular weight of the solute.

Pressure benzene= 103Torr at 298 K


Homework Equations



[tex]\Delta[/tex]T=Kfb (freezing point depression)

The Attempt at a Solution



For the first part I'm assuming I need to find Delta T and that is the freezing point depression but do not know how to figure out the molality (b) of the unknown substance. I know it is moles of solute per kilograms solvent but don't know how to determine the number of moles.
 
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  • #2
You have both freezing point depression and boiling point elevation in the same question.
 

1. What is physical chemistry?

Physical chemistry is a branch of chemistry that deals with the study of the physical properties and behavior of matter on a molecular and atomic level. It combines the principles of physics and chemistry to understand and explain how substances interact with each other and their surrounding environment.

2. What is dissolution in physical chemistry?

Dissolution refers to the process of a substance dissolving into a solvent to form a solution. This process involves the breaking of intermolecular forces between the solute particles and the subsequent mixing with the solvent to form a homogeneous mixture.

3. What factors affect the dissolution of a substance?

The dissolution of a substance is affected by several factors, including temperature, surface area, agitation, and the nature of the solute and solvent. Higher temperatures, increased surface area, and agitation can all increase the rate of dissolution, while the nature of the solute and solvent can also play a role in their ability to mix and form a solution.

4. What is solubility in physical chemistry?

Solubility is the maximum amount of a substance that can dissolve in a given amount of solvent at a specific temperature and pressure. It is often expressed in grams of solute per liter of solvent and can vary depending on the nature of the solute and solvent, as well as the temperature and pressure.

5. How is the dissolution of a substance measured?

The dissolution of a substance can be measured using various techniques, including gravimetry, spectrophotometry, and conductivity. Gravimetry involves measuring the change in mass of a solution before and after dissolution, while spectrophotometry measures the absorbance or transmission of light by the solution. Conductivity measures the ability of the solution to conduct electricity, which can be affected by the presence of dissolved ions.

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