calculate the molarity of 0.750 mol of na₂s in 1.80 l of solution. molarity: calculate the molarity of 20.9…

Explanation:

Step1: Recall molarity formula

Molarity ($M$) = $\frac{n}{V}$, where $n$ is the number of moles and $V$ is the volume of the solution in liters.

Step2: Calculate molarity for $Na_2S$

Given $n = 0.750$ mol and $V=1.80$ L. $M=\frac{0.750\ mol}{1.80\ L}=\frac{0.750}{1.80}\ mol/L \approx 0.417\ mol/L$

Step3: Calculate moles of $MgS$

The molar - mass of $MgS$: $M_{MgS}=24.31\ g/mol + 32.07\ g/mol=56.38\ g/mol$. $n=\frac{m}{M_{MgS}}$, where $m = 20.9$ g. $n=\frac{20.9\ g}{56.38\ g/mol}\approx0.371\ mol$

Step4: Convert volume of $MgS$ solution to liters

$V = 753\ mL=753\times10^{- 3}\ L = 0.753\ L$

Step5: Calculate molarity for $MgS$

$M=\frac{n}{V}=\frac{0.371\ mol}{0.753\ L}\approx0.493\ mol/L$

Answer:

For $Na_2S$: $0.417\ mol/L$ For $MgS$: $0.493\ mol/L$