Don't know how to do the calculations based on all these factors.

Unless otherwise stated, 5% HCl means 5% w/w.

Try this one:

What masses of 37% HCl(aq) stock solution and water should be mixed to prepare 1 kg of 5% HCl(aq)?

Now this one:

What volumes of 37% HCl(aq) stock solution (density = 1.19 kg/L) and water should be mixed to prepare 1 L of 5% HCl(aq) (density = 1.02 kg/L)?

Hi Dan, I went to do the questions you posted and I'm not sure if I'm right

First one: Consider in terms of kg

So, 37kg+63kg+x=total mass

To find x, 37/(63+x)=5 so x=677kg

37+63+677=777 for the total mass to be 1kg, mass of 37% HCl water=100/777 and mass of water added=677/777=0.87kg

Is this correct?

For the second question I'm not very sure how to answer it. I tried to equate the total mass/ total volume to 1.19 but i didn't get it. Here is my working total mass=100kg total volume=63kg=63l so density=100kg/63L=1.59kg/L . How is this wrong?

I tried it again after some thinking and here are my new workings:

Consider in kg and using first answer,

100kg+677kg/xL=1.02kg/L so xL=762L

however it needs to be 1L instead of 762L so, 777/762=1.02kg. In order to get the respect amounts i split them into 100kg/762L+677kg/762L

so the new mass of solution is 0.131kg and mass of water is 0.89kg. For their initial densities, 0.131kg/V1=1.19kg/L so V1=0.11L and 0.89kg/V2=1kg/L so V2=0.89L

Is this correct? Also, is taught in high school chemistry? Because i did not learn about these stuff.