the molarity of a solution containing 7.1 g of sodium sulfate in 100 ml of an aqueous solution is ______. a…
the molarity of a solution containing 7.1 g of sodium sulfate in 100 ml of an aqueous solution is ______. a 1 m b 0.5 m c 0.05 m d 2 m
Answer
Explanation:
Step1: Calculate molar mass of sodium sulfate ($Na_2SO_4$)
The molar mass of $Na$ is approximately 23 g/mol, $S$ is 32 g/mol and $O$ is 16 g/mol. So, $M_{Na_2SO_4}=2\times23 + 32+4\times16=142$ g/mol.
Step2: Calculate number of moles of sodium sulfate
The formula for number of moles $n=\frac{m}{M}$, where $m = 7.1$ g and $M = 142$ g/mol. So, $n=\frac{7.1}{142}=0.05$ mol.
Step3: Convert volume of solution to liters
The volume $V = 100$ mL. Since 1 L = 1000 mL, $V=100\div1000 = 0.1$ L.
Step4: Calculate molarity
The formula for molarity $M=\frac{n}{V}$. Substituting $n = 0.05$ mol and $V=0.1$ L, we get $M=\frac{0.05}{0.1}=0.5$ M.
Answer:
B. 0.5 M