A 4g sugar cube(sucrose: C12H12O11) is dissolved in a 350ml teacup of 80 degree water. what will be the molality of the sugar solution.
To calculate the molality of the sugar solution, we need to find the number of moles of sucrose and the mass of the solvent.
Step 1: Find the number of moles of sucrose (C12H22O11)
The molar mass of sucrose (C12H22O11) can be calculated by adding the molar masses of carbon, hydrogen, and oxygen:
12 * 12.01 g/mol (C) + 22 * 1.01 g/mol (H) + 11 * 16.00 g/mol (O) = 342.34 g/mol.
Now use the molar mass to calculate the number of moles of sucrose:
Number of moles of sucrose = Mass of sucrose / Molar mass
Number of moles of sucrose = 4 g / 342.34 g/mol = 0.01168 mol
Step 2: Find the mass of the solvent
The 350 ml of water weighs approximately 350 g since the density of water is about 1 g/ml (at room temperature).
Step 3: Calculate the molality
Molality (m) is defined as the number of moles of solute per kilogram of solvent.
Mass of solvent in kg = Mass of solvent in g / 1000
Mass of solvent in kg = 350 g / 1000 = 0.35 kg
Molality (m) = Number of moles of solute / Mass of solvent (in kg)
Molality (m) = 0.01168 mol / 0.35 kg = 0.03338 mol/kg
Therefore, the molality of the sugar solution is approximately 0.03338 mol/kg.
To find the molality of a sugar solution, you need to know the amount of solute (in moles) and the mass of the solvent (in kilograms). In this case, the solute is the sugar (C12H22O11), and the solvent is the water.
To find the amount of sugar (solute) in moles, we can use the molar mass of sucrose. The molar mass of sucrose is about 342.3 g/mol, which means that one mole of sucrose is approximately 342.3 grams.
To find the moles of sugar in the solution, you can use the mass of the sugar given. In this case, you are given a 4g sugar cube, so the number of moles of sugar is calculated as follows:
Number of moles = mass of sugar / molar mass
Number of moles = 4g / 342.3 g/mol
Now, we need to convert the volume of the water from milliliters to liters, as molality is typically expressed in moles of solute per kilogram of solvent.
To convert 350 ml to liters, you can divide by 1000:
Volume of water = 350 ml / 1000 ml/L = 0.35 L
Finally, we can calculate the molality of the sugar solution using the formula:
Molality = moles of solute / mass of solvent (in kg)
Molality = moles of sugar / mass of water (in kg)
We already calculated the moles of sugar (solute), and now we need to determine the mass of the water (solvent). Since the density of water is approximately 1 g/mL, we can assume that 0.35 L of water has a mass of 0.35 kg.
Now, we can substitute the values into the molality equation:
Molality = (4g / 342.3 g/mol) / 0.35 kg
Calculating this expression, we find the molality of the sugar solution.
0.021 mol/kg
molality = m = mols/kg solvent
mols sucrose = grams/molar mass
You don't know kg solvent. volume is 350 mL, look up density of water at 80 C, then mass = volume x density and convert mass in grams to kg.
Post your work if you get stuck.