Concentrated HCl is 37.5% HCl by weight and has a density of 1.19.?

Question

a) Describe the preparation of an HCl solution containing 25% HCl by weight.
b) Describe the preparation of a dilute HCl solution having a pH of 4.7

Answer 1

a)to make a solution of HCl having 25% by weight from a solution having 37.5% remark that 25/35.5=2/3. so you mix 2 parts of the concentrated solution of 37.5% with 1 part of water

b) pH of 4.7 means that concentration of H+

[H+] = 10^(-4.7) =2*10^-5M
A solution of 37.5% with a density of 1.19 contains
37.5*1.19/100=0.44625kg of HCl by litter and has a molarity of 446.25/36.5=12.2M
you must make a solution of 2*10^-5M

so dilute 2*10^-5/12.2 =1.64*10-6

In practice , I would dilute first 1000 times taking 1ml of the solution in 1 liter of water and after this taking 1.64ml of the diluted olution in 1 liter of water

Answer 2

Density Of Hcl

Answer 3

RE:
Concentrated HCl is 37.5% HCl by weight and has a density of 1.19.?
a) Describe the preparation of an HCl solution containing 25% HCl by weight.
b) Describe the preparation of a dilute HCl solution having a pH of 4.7

Answer 4

a) use the dilution equation M1V1=M2V2. You need to know how much you need (V2). Since the conversions from %s to molarity is the same you can treat 37.5% as M1 and 25% as M2, the conversion factors will cancel.

V1 = (M2/M1)*V2

So, you take V1 ammount of your 37.5% and dilute it to V2

b) pH = -log[H+], one mole of HCl yields 1 mole of H+. You would again use the dilution equation to figure out how much you need to dilute to 10^-4.7M, this solution will have a pH of about 4.7.

Realistically though, people use buffers to get a specific pH soloution in a laboratory. You calculate this by using the Henderson-Haukelbauck (sp) equation.

pH= pKa + log (A/HA) where A/HA is your salt/acid ratio