Question

the solubility in mol/dm3 of 20.2g of potassium trioxonitrate(V)dissolved in 100g of water at room temperature is​

Answer 1

Answer:

• 2.00 mol/dm³

Explanation:

Potassium trioxonitrate(V) is KNO₃.

1. Find the molar mass of the solute

The molar mass of KNO₃ is 39.098g/mol + 14.007g/mol + 3×15.999g/mol = 101.102g/mol.

2. Convert the mass of solute, 20.02g, into number of moles

• number of moles = mass in grams / molar mass

• number of moles = 20.2g / 101.102g/mol = 0.1998mol

3. Assume that the volume of the solution is equal to the volume of water

This is a rough approximation, but it is necessary since you do not have the density of the solution:

• density = mass / volume
• 1.00 g/cm³ = 100g / volume
• volume = 100g × 1.00g/cm³ = 100cm³

Convert 100cm³ to dm³:

• 100cm³ × 1dm³ / 1,000cm³ = 0.1 dm³

4. Calculate the solubility is mol/dm³

• 0.1998 mol / 0.1dm³ = 1.998mol/dm³ ≈ 2.00mol/dm³

It is rounded to three significant digits to match the choices.