How many grams of sucrose,C12H22O11 must be dissolved in 750.mL of water to prepare a 0.250 molal solution?
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64.1806
НЙДю
To determine the number of grams of sucrose (C12H22O11) that must be dissolved in 750 mL of water to prepare a 0.250 molal solution, we can follow these steps:
Step 1: Understand the problem
We want to find the mass of sucrose required to make a 0.250 molal solution. A molal solution represents the number of moles of solute per kilogram of solvent.
Step 2: Find the molar mass of sucrose
The molar mass of sucrose (C12H22O11) can be calculated by adding up the atomic masses of carbon, hydrogen, and oxygen. The atomic masses are:
Carbon (C) = 12.01 g/mol
Hydrogen (H) = 1.01 g/mol
Oxygen (O) = 16.00 g/mol
Now we can calculate the molar mass of sucrose:
Molar mass of C12H22O11 = (12 * 12.01) + (22 * 1.01) + (11 * 16.00) = 342.3 g/mol
Step 3: Convert moles to kilograms
To convert the molal concentration to mass, we need to convert the volume of the solvent (water) to kilograms. Since the given volume is in milliliters (mL), we need to convert it to kilograms.
1 mL of water weighs approximately 1 gram (g), and 1000 grams (1 kg) make up 1 kilogram.
So, 750 mL = 750 g = 0.75 kg
Step 4: Calculate the number of moles
The molality (molal concentration) is given as 0.250 mol/kg. Since we know the molality and the mass of the solvent, we can calculate the moles of sucrose:
Moles of sucrose = molality * mass of solvent in kg
Moles of sucrose = 0.250 mol/kg * 0.75 kg
Step 5: Calculate the mass of sucrose
Now, we can calculate the mass of sucrose in grams by multiplying the number of moles with the molar mass:
Mass of sucrose = Moles of sucrose * molar mass of sucrose
Mass of sucrose = (0.250 mol/kg * 0.75 kg) * 342.3 g/mol
If we calculate this expression, we find that the mass of sucrose that must be dissolved in 750 mL of water to prepare a 0.250 molal solution is approximately 64.62 grams.
.250=gramsSucrose/(molmassSucrose*.750)
solve for gramsSucrose.