a solution is made by dissolving 25 g NaCl in enough water to make 1.0 L solution. Assume that density of the solution is 1.0 g/mL. calculate the mass percent, molarity, molality, and mole fraction of NaCl.
whats wrong
25 g NaCl 1.0 L solution
1.0 g/mL
25 g NaCl/58.44 g NaCl= .428 mol
25g/58.44g x100= 42.8% mass percent
1000g solvent (H20)
molarity- .428 mol/1.0 L= .428 M
molality- .428 mol/1 kg= .428 molal
whats wrong? idk
responded below.
mass % should be 2.5%. M and m are right.
There doesn't appear to be anything wrong with the calculations you provided. The mass percent, molarity, molality, and mole fraction of NaCl are correctly calculated based on the given information. However, it's important to note that the density of the solution is 1.0 g/mL, which suggests that the density of water is 1.0 g/mL as well. In reality, the density of water is slightly less than 1.0 g/mL at room temperature.
Based on the information you provided, there doesn't appear to be anything wrong with your calculations. You correctly determined the mass percent, molarity, and molality of the NaCl solution. However, you didn't calculate the mole fraction of NaCl.
To calculate the mole fraction of NaCl, you need to know the moles of the solvent (water) as well. Since the density of the solution is 1.0 g/mL and you have 1.0 L of solution, the mass of the solution is 1000 g (1.0 g/mL * 1000 mL = 1000 g).
To find the moles of water, you can use the molar mass of water, which is 18.015 g/mol. Divide the mass of the water by its molar mass:
1000 g water / 18.015 g/mol = 55.49 mol water
Now, to calculate the mole fraction of NaCl (X_NaCl), you can use the following formula:
X_NaCl = moles of NaCl / (moles of NaCl + moles of water)
X_NaCl = 0.428 mol NaCl / (0.428 mol NaCl + 55.49 mol water)
Simplifying this equation will give you the mole fraction of NaCl.
I hope this explanation helps! Let me know if you have any additional questions.