Question

1. what is the molarity of 18 g of hcl dissolved in enough water to make a 750.0 solution?

Explanation:

Step1: Calculate moles of HCl

The molar mass of HCl is $M_{HCl}=1.01 + 35.45=36.46\ g/mol$. The number of moles $n$ of HCl is calculated by $n=\frac{m}{M}$, where $m = 18\ g$. So $n=\frac{18\ g}{36.46\ g/mol}\approx0.494\ mol$.

Step2: Calculate molarity

The formula for molarity $M$ is $M=\frac{n}{V}$, where $V$ is the volume of the solution in liters. Given $V = 750.0\ mL=0.7500\ L$. Then $M=\frac{0.494\ mol}{0.7500\ L}\approx0.659\ M$.

Answer:

$0.659\ M$