# How many litres of hydrogen chloride gas at STP are required to prepare 2.0L or 2.0M of Hyrdochloric acid?

Hydrochloric acid is commonly prepared by bubbling gaseous hydrogen chlored into distilled water. How many litres of hydrogen chloride gas at STP are required to prepare 2.0L or 2.0M of Hyrdochloric acid?

I am just confused on where to start.

HCL = Hydrogen Chloride

HCL (aq) = Hydrochloric Acid

Molecular Mass I determined was 36.46094

I need

N=2mol

C=2mol

So am I trying to find the mass number, like converting grams into litres? But that only works with water.

These are the two formulas available.

C = N/V

C1V1 = C2V2

Update:

I understand, I really wish my teacher gave us a constants sheet with STP on it. However if STP, the volume is always 22.4? I always thought STP was 273K, 101.325Kpa. So its moles = volume/22.4L. Got it, Thx for the quick reply, I'll best answer you asap.

Relevance

Hi!

At STP the Volume is 22.4 litres

Molar volume at STP = 22.4 litres / mole ( It can be written as for any idea gas)

Molarity = 2.0 M or 2.0 moles / litre

Litres = 2.0 litres

Find the moles of HCl(g) = 2.0 moles / litre * 2.0 litres

Moles = 4.0 moles

Now 4.0 moles of HCl

Multiply moles of HCl by molar volume at STP

4.0 moles of HCl * 22.4 litres / 1 mole

Moles cancel out and you have

89.6 litres or 90 L

Hope it helps! Good luck!

Edit:

Sorry for this late edit.

STP means standard temperature pressure.

Temperature is O degree C or 273 K

Pressure is 101.3 KPa

The volume is said to be 22.4 litres at STP . It is always 22.4 litres.

For 1 mole of any ideal gas the volume is always 22.4 litres

I am not sure you have learned this or not.

but this is idea gas law formula

PV = nRT

Now taking the number of moles as 1 and taking the stp values

Pressure = 101.3 KPa

moles = 1

R = 8.31 KPa.Litres / mole . Kelvin

T = 273 K

Now to find volume rearranging the equation we get

V= nRT/P

Volume = 1 mole * 8.31 KPa.Litres * Moles ^-1 * Kelvin ^-1 * 273 K / 101.3Kpa

if you write this down all units cancel out except Litres which is

22.39516....

or in 3 sigs

22.4 litres

This is true for any ideal gas of 1 mole.

Say O2 at stp We can do the same conversion and find Volume

We define molar volume as the volume / mole at STP or SATP depending on the conditions asked in the question.

22.4 litres/ mol = molar volume at STP

24.8 litres/mol = Molar Volume at SATP

These are two things which is helpful to remember. When the questions asks for converting from moles to litre at STP it is easier to just put this in and solve.

I could have done the pv=nRT and found the volume but that would be a longer step. Instead i can find it out like this in a matter of seconds.

PV = nRT

V = nRT / P

V = 4 moles * 8.31 * 273 K / 101.3 KPA

V= 89.58065153.....

or Volume = 90 L

The point is using molar volume it is easier and better for conversion if your given moles and finding volume at STP .

Again remember these values. It was really helpful for my gr 11 exam

AT STP = 22.4 litres

AT SATP =24.8 litres ( 2.4 is the difference between the volumes)

Hope this clear your doubts. Any questions ask again in the additional question or send me an email.

Good luck!

• Anonymous
4 years ago

Hydrogen Chloride (HCl) gas is acidic in nature because it dissolves in water (polar solvent) to dissasociate into H+ (Hydrogen ions) and Cl- (Chloride ions) ions. The H+ ions are what make it acidic. word: As a gas it isn't acidic. in easy words even as dissolved in water (or any polar solvent) does it teach acidic houses. It turns damp (so there is water cutting-edge) blue litmus paper pink proving that's acidic.