Question

Given that the molar mass of NaOH is 40.00 g/mol, what mass of NaOH is needed to make 2.500 L of a 2.000 M NaOH solution?
Use Molarity equals StartFraction moles of solute over liters of solution EndFraction..
0.1250 g
5.000 g
32.00 g
200.0 g

Answer 1

To calculate the mass of NaOH needed to prepare a 2.500 L solution at a concentration of 2.000 M, we can use the formula for molarity:

\[
M = \frac{\text{moles of solute}}{\text{liters of solution}}
\]

First, we will calculate the number of moles of NaOH required:

\[
\text{moles of NaOH} = M \times \text{liters of solution} = 2.000 \, \text{mol/L} \times 2.500 \, \text{L} = 5.000 \, \text{mol}
\]

Next, we will convert moles of NaOH to grams using its molar mass:

\[
\text{mass of NaOH} = \text{moles of NaOH} \times \text{molar mass of NaOH} = 5.000 \, \text{mol} \times 40.00 \, \text{g/mol} = 200.0 \, \text{g}
\]

Therefore, the mass of NaOH needed to make 2.500 L of a 2.000 M NaOH solution is **200.0 g**.