an aq. solution(NaCl) made by using 133g diluted to a total solution volume of 1 L.Calculate the molarity, molality & mass % of the solution(density of solution = 1.08g/mL)
[ans: M=1.92M, m=2.0m, 10.4 %]
i need the calculation work bcus my ans is contradict from the real ans.
~for M i got 2.28M
my calculation: M=2.28/1
but the ans is 1.92M.
~for the mass% i got 12.31%
my calculation: mass%=133/1080x100%
but the ans is 10.4%
To find the molarity, molality, and mass percent of the solution, we need to perform the following calculations step by step:
Step 1: Calculate the number of moles of NaCl.
Molar mass of NaCl (sodium chloride) = 23 + 35.45 = 58.45 g/mol
Number of moles of NaCl = Mass of NaCl / Molar mass of NaCl
Number of moles of NaCl = 133 g / 58.45 g/mol
Number of moles of NaCl ≈ 2.276 mol
Step 2: Calculate the volume of the solution in liters.
Volume of solution = Mass of solution / Density of solution
Volume of solution = 1000 g / 1.08 g/mL
Volume of solution ≈ 925.93 mL ≈ 0.926 L
Step 3: Calculate the molarity.
Molarity (M) = Number of moles of solute / Volume of solution in liters
Molarity (M) = 2.276 mol / 0.926 L
Molarity (M) ≈ 2.46 M
Step 4: Calculate the molality.
Molality (m) = Number of moles of solute / Mass of solvent in kg
Mass of solvent = Mass of solution - Mass of solute
Mass of solution = 1000 g
Mass of solute = 133 g
Mass of solvent = 1000 g - 133 g = 867 g = 0.867 kg
Molality (m) = 2.276 mol / 0.867 kg
Molality (m) ≈ 2.62 m
Step 5: Calculate the mass percent.
Mass percent = (Mass of solute / Mass of solution) × 100%
Mass percent = (133 g / 1000 g) × 100%
Mass percent ≈ 13.3%
So, after performing the calculations, the correct results would be:
Molarity (M) ≈ 2.46 M
Molality (m) ≈ 2.62 m
Mass percent ≈ 13.3%
To calculate the molarity, molality, and mass percentage of the NaCl solution, we'll need to follow a step-by-step calculation process. Let's break it down:
Step 1: Calculate the moles of NaCl in the solution.
Moles = mass / molar mass
Molar mass of NaCl = 23g/mol for Na + 35.5g/mol for Cl
Moles = 133g / (23g/mol + 35.5g/mol) = 133g / 58.5g/mol = 2.28 mol
Step 2: Calculate the volume of the solution in liters.
Volume = mass / density
Mass of the solution = 133g
Density of the solution = 1.08g/mL
Volume = 133g / 1.08g/mL = 123.15 mL = 0.12315 L
Step 3: Calculate the molarity of the solution.
Molarity = moles / volume
Molarity = 2.28 mol / 0.12315 L = 18.53 M (rounding to two decimal places = 18.53 M)
Step 4: Calculate the molality of the solution.
Molality = moles / mass of the solvent (in kg)
Mass of the solvent = mass of the solution - mass of solute
Mass of the solution = 133g
Mass of solute (NaCl) = 2.28 mol x (23g/mol + 35.5g/mol) = 2.28 mol x 58.5g/mol = 133.38g
Mass of the solvent = 133g - 133.38g = -0.38g (Since the mass of the solvent is negative, there was an error in your question as it is not physically possible. A negative mass would imply that you have removed more solute than you actually had initially.)
Calculation cannot be continued further due to the error in mass of solvent calculation. Please double-check the given data and redo the calculation.
I don't want to work the problem for you but here are the definitions. Actually, that's all you need with the data you have.
M = #moles/L soln
m = #moles/kg solvent
mass% = grams solute/100 g soln
You get moles from grams/molar mass.
You convert g to kg by dividing by 1000 (moving the decimal point to the left three places).
The density equation is
mass = volume x density.