If exactly 100.0 grams of NaCl (molecular mass = 58.44 g/mol) are dissolved in 300 grams of water (molecular mass = 18.02 g/mol), the mole fraction of NaCl is
a) 1.71
b) 0.0932
c) 0.250
d) 0.103
e) 4.75
moles NaCl = grams/molar mass.
moles H2O = grams/molar mass
total moles = nH2O + nNaCl
XNaCl = n NaCl/total moles.
To find the mole fraction of NaCl in the solution, we first need to calculate the number of moles of NaCl and water separately.
First, calculate the number of moles of NaCl:
Number of moles of NaCl = mass of NaCl / molar mass of NaCl
Number of moles of NaCl = 100.0 g / 58.44 g/mol
Number of moles of NaCl = 1.71 mol
Next, calculate the number of moles of water:
Number of moles of water = mass of water / molar mass of water
Number of moles of water = 300 g / 18.02 g/mol
Number of moles of water = 16.65 mol
The mole fraction of NaCl can be calculated by dividing the moles of NaCl by the total moles of the solution:
Mole fraction of NaCl = moles of NaCl / (moles of NaCl + moles of water)
Mole fraction of NaCl = 1.71 mol / (1.71 mol + 16.65 mol)
Mole fraction of NaCl = 1.71 mol / 18.36 mol
Mole fraction of NaCl ≈ 0.0932
Therefore, the mole fraction of NaCl in the solution is approximately 0.0932.
Answer: b) 0.0932