Question

рассчитать молекулярный вес мочевины ,если водный раствор ,содержащий 0,368 г мочевины в 200 см3 воды при 20 градусах,имеет осматическое давление 74 630 Па.

Answer 1

закон менделеева-клайперона: PV=mRT/M

M=mRT/PV=60

Answer 2

Calculation of Molecular Weight of Urea

To calculate the molecular weight of urea, we need to know the mass of urea and the number of moles of urea in the given solution. The molecular weight of urea can be calculated using the formula:

Molecular weight (g/mol) = Mass of urea (g) / Number of moles of urea

Let's calculate the number of moles of urea first.

Given: - Mass of urea = 0.368 g - Volume of water = 200 cm³ - Osmotic pressure = 74,630 Pa

To calculate the number of moles of urea, we can use the ideal gas law equation:

Osmotic pressure = (Number of moles of solute / Volume of solvent) * R * Temperature

Where: - R is the ideal gas constant (8.314 J/(mol·K)) - Temperature is in Kelvin

Since we are given the osmotic pressure in Pascals, we need to convert it to atmospheres (atm) before using the equation. 1 atm = 101325 Pa.

Converting the osmotic pressure to atm: Osmotic pressure (atm) = 74,630 Pa / 101325 Pa/atm

Now, let's calculate the number of moles of urea:

74,630 Pa / 101325 Pa/atm = (Number of moles of urea / 0.2 L) * 0.0821 L·atm/(mol·K) * 293 K

Simplifying the equation, we get:

Number of moles of urea = (74,630 Pa / 101325 Pa/atm) * 0.2 L / (0.0821 L·atm/(mol·K) * 293 K)

Now that we have the number of moles of urea, we can calculate the molecular weight using the given mass of urea:

Molecular weight (g/mol) = 0.368 g / Number of moles of urea

Let's calculate the molecular weight of urea using the given values.

Calculation:

1. Convert osmotic pressure to atm: - Osmotic pressure (atm) = 74,630 Pa / 101325 Pa/atm - Osmotic pressure (atm) = 0.736

2. Calculate the number of moles of urea: - Number of moles of urea = (0.736 atm * 0.2 L) / (0.0821 L·atm/(mol·K) * 293 K) - Number of moles of urea = 0.00599 mol

3. Calculate the molecular weight of urea: - Molecular weight (g/mol) = 0.368 g / 0.00599 mol - Molecular weight (g/mol) = 61.4 g/mol

Therefore, the molecular weight of urea is approximately 61.4 g/mol.