Answer:
The highest molality will be for the NH₄NO₃ . Option 5.
Explanation:
In order to determine which of the salts has the highest molality we must know the moles of each
10 g / 149.89 g/mol = 0.0667 moles NaI
10 g / 166 g/mol = 0.0602 moles KI
10 g / 147.4 g/mol = 0.0678 moles of RbNO₃
10 g / 80 g/ mol = 0.125 moles of NH₄NO₃
To determine molality we convert the mass of solvent (water) from g to kg
800 g . 1kg / 1000 g = 0.8 kg
Molality means the moles of solute in 1kg of solvent
0.0667 moles NaI / 0.8 kg of water = 0.083 m
0.0602 moles KI / 0.8 kg of water = 0.0752 m
0.0678 moles of RbNO₃ / 0.8 kg of water = 0.0847 m
0.125 moles of NH₄NO₃ / 0.8 kg of water = 0.156 m
