The molarity of a solution prepared by dissolving 15.0 grams of NaCl in 100 mL water is 0.15 M.
True or False
True
Probably you want moles NaCl = grams/molar mass, then
M = mols/L soln. Technically, however, you can't solve this problem without knowing the density BECAUSE adding 15.0 g NaCl to 100 mL water is not the same as adding 15.0 g NaCl to enough water to make 100 mL of SOLUTION. If I were answering the question I would answer false and argue with the prof if s/he counted it wrong but for the reason I just cited and not the fact that 15.0 g/100 mL SOLN is 2.56M soln.
True.
To determine the molarity of a solution, we need to calculate the number of moles of solute (NaCl) and divide it by the volume of the solution in liters.
First, we need to convert the mass of NaCl from grams to moles. The molar mass of NaCl is 58.44 g/mol.
Using the formula:
moles = mass / molar mass
moles = 15.0 g / 58.44 g/mol
moles = 0.257 moles
Next, we need to convert the volume of the solution from mL to L. There are 1000 mL in 1 L.
volume = 100 mL / 1000 mL/L
volume = 0.1 L
Finally, we can calculate the molarity using the formula:
molarity = moles / volume
molarity = 0.257 moles / 0.1 L
molarity = 2.57 M
Since the molarity of the solution is given as 0.15 M, which is different from the calculated value, the statement is false.
To determine if the statement is true or false, we need to calculate the molarity of the solution and compare it to the given value.
Molarity (M) is defined as the number of moles of solute per liter of solution. Therefore, we need to calculate the number of moles of NaCl in the solution and divide it by the volume of the solution in liters.
To begin, we need to convert the mass of NaCl to moles using its molar mass. The molar mass of NaCl is the sum of the atomic masses of sodium (Na) and chlorine (Cl), which is approximately 58.44 grams/mole.
Given:
Mass of NaCl = 15.0 grams
Molar mass of NaCl = 58.44 grams/mole
Volume of the solution = 100 mL = 0.1 L (converted to liters)
First, we calculate the moles of NaCl:
moles of NaCl = mass of NaCl / molar mass of NaCl
moles of NaCl = 15.0 grams / 58.44 grams/mole
Next, we calculate the molarity of the solution:
Molarity (M) = moles of NaCl / volume of the solution in liters
Molarity (M) = (15.0 grams / 58.44 grams/mole) / 0.1 L
Now, let's calculate the molarity:
Molarity (M)= (15.0 / 58.44) / 0.1
By performing this calculation, we find:
Molarity (M) ≈ 0.256 M (rounded to three significant figures)
Comparing this result to the given value of 0.15 M, we can conclude that the statement is False. The actual molarity is approximately 0.256 M, not 0.15 M.