Question

calculate the mass required to prepare 2.5 L of 1.0 M NaOH solution. Given that the molar mass for NaOH is 40 g/mol.

Answer 1

Answer:

$100\; \rm g$ of ${\rm NaOH}\; (s)$ would be required.

Explanation:

The quantity of solute in a solution of concentration $c$ and volume $V$ would be $n = c \cdot V$.

It is given that volume $V = 2.5\; \rm L$ for the solution in this question. It is also given that the concentration of the $\rm NaOH$ solute in this solution is $c = 1.0\; \rm M$, which is the equivalent to $c = 1.0\; \rm mol \cdot L^{-1}$.  

Apply the equation $n = c \cdot V$ to find the quantity of $\rm NaOH$ in this solution:

$\begin{aligned}n &= c \cdot V \\ &= 1.0\; \rm mol \cdot L^{-1} \times 2.5\; \rm L \\ &= 2.5\; \rm mol\end{aligned}$.

Multiply the quantity $n$ of $\rm NaOH$ in this solution with the formula mass $M$ of ${\rm NaOH}\!$ to find the corresponding mass:

$\begin{aligned}m &= n \cdot M \\ &= 2.5\; \rm mol \times 40\; \rm g \cdot mol^{-1} \\ &= 100\; \rm g\end{aligned}$.

Thus, this solution would contain $100\; \rm g$ of ${\rm NaOH}$.

It would thus take $100\; \rm g$ of ${\rm NaOH}$ to prepare this solution.

Answer 2

Answer:

The required mass to prepare 2.5 L of 1.0 M NaOH solution is 100 g

Explanation:

We do this by preparing the equation:

Mass = concentration (mol/L) x volume (L) x Molar mass

Mass = 1.0 M x 2.5 L x 40 g/mol

Mass = 100 g