Question

27.0 L of HCl gas at STP is dissolved in water, giving 785 mL of solution. What is the molarity of the HCl solution? 9.46 M

Answer 1

Answer:

Molarity = 1.53 M

Explanation:

At STP,  

Pressure = 1 atm  

Temperature = 273.15 K

Given, Volume = 27.0 L

Using ideal gas equation as:

$PV=nRT$

where,  

P is the pressure

V is the volume

n is the number of moles

T is the temperature  

R is Gas constant having value = 0.0821 L.atm/K.mol

Applying the equation as:

1 atm × 27.0 L = n × 0.0821 L.atm/K.mol × 273.15 K  

⇒n = 1.20 moles

Given that volume = 785 mL

Also,  

$1\ mL=10^{-3}\ L$

So, Volume = 785 / 1000 L = 0.785 L

Considering:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

$Molarity=\frac{1.20}{0.785}$

Molarity = 1.53 M