5.85g of sodium chloride is dissolved in 250mL of solution. Calculate: a)the molarity of the solution b)the mass percentage of the solute. can we use the given volume(i.e,250mL as total volume of the solution or volume of water in this problem?
2.2%
Molarity 0.4
chemistry
Gemeda
Molarity 0.4
To solve this problem, you need to use the given volume of 250 mL as the total volume of the solution. The molarity of the solution can be calculated using the formula:
Molarity (M) = moles of solute / volume of solution in liters
To calculate the molarity:
a) Convert the given mass of sodium chloride from grams to moles.
To do this, we need to know the molar mass of sodium chloride, which is the sum of the atomic masses of sodium (Na) and chlorine (Cl):
Molar mass of Na = 22.99 g/mol
Molar mass of Cl = 35.45 g/mol
Add the molar masses together to get the molar mass of NaCl:
Molar mass of NaCl = 22.99 g/mol + 35.45 g/mol = 58.44 g/mol
Now, divide the given mass of sodium chloride (5.85 g) by the molar mass of NaCl to get the moles of sodium chloride:
Moles of NaCl = 5.85 g / 58.44 g/mol
b) Calculate the volume of the solution in liters.
Given volume = 250 mL
To convert mL to liters, divide by 1000 (since 1 L = 1000 mL):
Volume of solution = 250 mL / 1000 mL/L = 0.250 L
c) Divide the moles of sodium chloride by the volume of the solution in liters to obtain the molarity:
Molarity (M) = Moles of NaCl / Volume of solution
Now, substitute the values into the formula to calculate the molarity.
Molarity = (5.85 g / 58.44 g/mol) / 0.250 L
Simplify the calculation:
Molarity = 0.1 mol / 0.250 L
Molarity = 0.4 M
Therefore, the molarity of the solution is 0.4 M.
To calculate the mass percentage of the solute, you need to find the ratio of the mass of sodium chloride to the total mass of the solution, and then multiply by 100 to express it as a percentage.
Mass percentage of solute = (mass of solute / mass of solution) * 100
a) The mass of the solute is the given mass of sodium chloride, 5.85 g.
b) To find the mass of the solution, you need to know the density of the solution, as the volume alone cannot determine the mass of the solution. The density of the solution is typically given or can be measured experimentally.
Once you have the mass of the solution, substitute the values into the formula to calculate the mass percentage of the solute.
2.3
Molarity 0.4
Mass percentage 2.2 %
The problem tells you that the total solution is 250 mL. However, in the absence of more information I think you must use it both ways.
mols NaCl = grams/molar mass, then M = mols/L soln.
% w/w = (g solute/(250+5.85)*100 = ?
Technically I don't think you can calculate % w/w since you don't know the density of the solution.