I need help on these questions. They all seem pretty similar i think? i don't know what formula i am suppose to use. And what does nonvolatile mean? is that like a clue or something?
1) 2.6 g of the nonvolatile solute sucrose (C12H22O11) is added to 465 g of water at 25oC. What will be the partial pressure of the water vapor over this solution?
_____ mmhg
2) The partial pressure of water above a solution of water and a nonvolatile solute at 25oC is 19.5 mm Hg. What is the mole fraction of the solute?
3)The boiling point elevation of a solution consisting of 2.53 g of a nonvolatile solute in 96.3 g of benzene is 0.7690 C. What is the molecular weight of the unknown solute?
____g/mol
( for this one i know i am suppose to figure out the moles of it then divide the grams by the mole. HOW DO I FIND OUT THE MOLES??)
For 1 and 2, I'll bet you can find the equations in your text under Raoult's Law. For #3, use delta T = Kb*m. You will need to look up Kb for benzene (look under boiling point elevation constant).
a gaseous organofluorine compound has a density of 0.355 g/l at 307 degrees celsius
To solve these questions, you need to use different formulas related to the properties of solutions. Let's break down each question and explain the relevant formulas and concepts.
1) The first question asks for the partial pressure of water vapor over the solution. This problem involves the concept of "nonvolatile," which refers to a solute that does not evaporate easily. To solve this, we need to use Raoult's Law, which states that the partial pressure of a solvent is equal to the product of its vapor pressure (in pure form) and the mole fraction of the solvent in the solution.
The formula is: P₁ = P₀₁ * X₁
Where:
P₁ is the partial pressure of water vapor over the solution.
P₀₁ is the vapor pressure of water (which can be looked up in a table) at the given temperature.
X₁ is the mole fraction of water in the solution.
2) The second question asks for the mole fraction of the solute based on the given partial pressure of water above the solution. The mole fraction is the ratio of moles of solute to the total moles of the solution. To solve this, we will use Raoult's Law again but rearrange the formula to solve for X₁ (mole fraction).
The formula is: X₁ = P₁ / P₀₁
Where:
X₁ is the mole fraction of the solute.
P₁ is the partial pressure of water vapor over the solution.
P₀₁ is the vapor pressure of water (at the given temperature).
3) The third question involves the boiling point elevation caused by adding a nonvolatile solute to the solvent. This problem deals with colligative properties, specifically boiling point elevation. The formula to calculate the boiling point elevation is:
∆Tb = Kb * m
Where:
∆Tb is the boiling point elevation.
Kb is the molal boiling point constant (which can be given or looked up in a table) for the solvent.
m is the molality of the solute in the solution.
To find the molecular weight of the unknown solute, you will need to convert the given mass of the solute into moles. You can do this using the formula:
moles = mass / molar mass
Where:
moles is the number of moles of the solute.
mass is the mass of the solute given in the question.
molar mass is the molecular weight of the solute.
Once you have the number of moles of the solute, you can calculate the molality (m) using the formula:
m = moles of solute / mass of solvent (in kg)
Finally, you can rearrange the boiling point elevation formula to solve for the molecular weight of the unknown solute:
molar mass = ∆Tb / (Kb * m)
Where:
molar mass is the molecular weight of the solute.
∆Tb is the boiling point elevation from the question.
Kb is the molal boiling point constant for the solvent.
m is the molality of the solute.
Remember to convert the units in the formula to be consistent (e.g., grams to kilograms, Celsius to Kelvin) before plugging in the values.
I hope this helps! Let me know if you have any further questions.