calculate the molality of a solution formed by dissolving 27.8g of LiI in 500mL of water
mols LiI = grams/molar mass = ?
m - mols LiI/kg solvent = ?
Calculate the molality of a solution formed by dissolving 27.8g lit in 500ml of water.
Calculate the molality of a solution formed by dissolving 27.8g lit in 500ml of water.
To calculate the molality of a solution, you need to know the mass of the solute and the mass of the solvent. In this case, the solute is 27.8g of LiI (lithium iodide) and the solvent is 500mL of water.
Step 1: Convert the volume of the solvent from milliliters to liters.
Since 1 liter is equal to 1000 milliliters, we can convert 500mL to liters by dividing by 1000.
500mL ÷ 1000 = 0.500 liters
Step 2: Convert the mass of the solute to moles.
To convert the mass of LiI to moles, we need to use the molar mass of LiI. The molar mass of lithium (Li) is approximately 6.94 g/mol, and the molar mass of iodine (I) is approximately 126.9 g/mol. Add those together to find the molar mass of LiI:
6.94 g/mol + 126.9 g/mol = 133.84 g/mol
Now, divide the mass of the solute by the molar mass to find the number of moles:
27.8g ÷ 133.84 g/mol = 0.2076 mol
Step 3: Calculate the molality.
Molality (m) is the number of moles of solute divided by the mass of the solvent in kg.
The mass of the solvent is already in liters, but we need to multiply it by the density of water to convert it to kilograms. The density of water is approximately 1 g/mL, so the mass of the solvent is:
0.500 liters × 1000 g/L = 500 g
Now, convert the mass of the solvent from grams to kilograms by dividing by 1000:
500 g ÷ 1000 = 0.500 kg
Finally, divide the number of moles of solute by the mass of the solvent in kilograms to find the molality:
0.2076 mol ÷ 0.500 kg = 0.415 mol/kg
Therefore, the molality of the solution formed by dissolving 27.8g of LiI in 500mL of water is approximately 0.415 mol/kg.