you have to prepare 200ml of a 0.2M NaCl solution. calculate the mass of NaCl you will need
How many mols do you need? That's M x L = ?
Then mols NaCl = grams NaCl/molar mass NaCl = ?
To calculate the mass of NaCl you will need to prepare a 0.2M NaCl solution, you need to know the molar mass of NaCl.
The molar mass of NaCl is calculated by summing the atomic masses of sodium (Na) and chlorine (Cl). The atomic masses of sodium and chlorine are approximately 22.99 g/mol and 35.45 g/mol, respectively.
So, the molar mass of NaCl = 22.99 g/mol + 35.45 g/mol = 58.44 g/mol.
Now, using the formula for calculating molarity:
Molarity (M) = moles of solute / volume of solution in liters
We know the desired molarity (0.2M), and we have the volume of the solution (200 mL = 0.2 L).
So, let's rearrange the formula to solve for moles of solute:
moles of solute = Molarity x volume of solution in liters
moles of solute = 0.2M x 0.2 L = 0.04 moles
Now, to find the mass of NaCl needed, we'll use the equation:
mass = moles of solute x molar mass
mass = 0.04 moles x 58.44 g/mol
Therefore, the mass of NaCl you will need to prepare a 0.2M NaCl solution is approximately 2.34 grams.