Colligative Properties

Flashcards on colligative properties, including concentration units, normality, molarity, molality, mole fraction, Raoult's Law, vapor pressure lowering, boiling point elevation, freezing point depression, osmosis, and osmotic pressure.

What is a binary solution?

A solution consisting of two components, a solute and a solvent.

What is the name given to the number of gram equivalents of solute dissolved in one litre of a solution?

Normality (N)

How do you calculate the equivalent mass of a substance?

Ratio of the molecular mass of the substance to its charge number (either positive or negative).

What formula relates the mass of solute (w), volume of solution (v), equivalent mass (E), and normality (N)?

N = (w * 1000) / (E * v)

What is the formula of Molarity?

M = (w * 1000) / (M' * v)

What is the formula for Molality?

m = (w * 1000) / (M' * w')

What is the formula for calculating the mole fraction of a component A (XA) in a solution?

XA = nA / (nA + nB), where nA is the number of moles of component A and nB is the number of moles of component B.

What is the definition of colligative properties?

Properties of solutions that depend only on the number of solute particles and not on the nature of the solute.

List the four colligative properties?

Relative Lowering of Vapor Pressure (RLVP), Elevation in Boiling Point (EBP), Depression in Freezing Point (DFP), and Osmotic Pressure (OP).

What is Raoult's Law?

The vapor pressure of a solvent in a solution is equal to the product of the vapor pressure of the pure solvent and the mole fraction of the solvent: psolv = (p0solv) * (xsolv).

According to Raoult's Law, what is relative lowering of vapor pressure?

Relative Lowering of V.P is equal to the mole fraction of solute

What equation is used to determine the molecular mass of a non-volatile solute by lowering of vapor pressure?

m = (w * M * P0solv) / (W * (P0solv - Psoln))

What is the principle behind Ostwald-Walker's method for determining the lowering of vapor pressure?

A non-volatile solute lowers the vapour pressure of a solvent.

Define elevation of boiling point (∆Tb).

The increase in the boiling point of the solvent on the addition of a solute to it.

What is the relationship between the elevation in boiling point (∆Tb) and the molality (m) of the solution?

∆Tb = Kb * m, where Kb is the molal elevation constant or ebullioscopic constant.

Why is boiling point elevation (ΔTb) a colligative property, but boiling point is not?

Boiling point elevation (ΔTb) is a colligative property because it depends on solute concentration, while the boiling point itself is not, as it is affected by multiple factors, including the nature of the liquid.

Define depression of freezing point (∆Tf).

The lowering of the freezing point of a solvent on the addition of a solute.

What is the relationship between the depression in freezing point (∆Tf) and the molality (m) of the solution?

∆Tf = Kf * m, where Kf is the molal depression constant or cryoscopic constant.

Define Osmosis

The spontaneous flow of the solvent molecules through a semi-permeable membrane from pure solvent to solution OR from less concentrated solution to more concentrated solution is called Osmosis.

Define Osmotic Pressure (π).

The excess pressure which must be exerted on the solution side in order to prevent the flow of solvent molecules towards the solution side through semi-permeable membrane.

What is the Van't Hoff equation relating osmotic pressure (π), molarity (C), gas constant (R), and temperature (T)?

π = CRT

What is the formula for calculating the molecular mass using osmotic pressure?

m = (w * R * T) / (π * v)

Define Isotonic solutions

Solution Have the same solute concentration as another solution, resulting in no net movement of water

Define Hypotonic Solutions

Solution Have a lower solute concentration than another solution, causing water to move into the cell.

Define Hypertonic Solutions

Solution Have a higher solute concentration than another solution, causing water to move out of the cell.