Ask a question
0 0

chemistry find mass

i am so confused why i find two different answers while i did in two different ways!
I have 60ml 1M HCL    The question asks me to find the mass of HCl.
1. m=0.06L*(1mol / 1L)*(36.458g/mol) = 2.18748g
2. m=density*volume= 1g/cm3*60ml= 60g
Tutors, please sign in to answer this question.

4 Answers

1. It is correct.
2. It can work if you convert mole density to mass density. The density here means the density of HCl, not the density of water. Here is the work:
1M of HCl = (36.458g/L) of HCl
density*volume = (36.458g/L)(0.06 L) = 2.18748 g of HCl
1 M Hcl solution contain 1 mole of Hcl in one liter solution ..
that mean nearly 36.5 gm of Hcl is dessolve in 1 liter(1000ml) solution
then  grm of Hcl in 6o ml solution...=60*36.5 =2190 gm/1000 =2.190 gm of Hcl in 60 ml 1M solutiion.
Your calculation in 1. is right.
In 2. you are calculating the mass of the entire 60 mL aqueous solution, most of which is just water. Its density is a little higher than that of water, depending on the concentration. For this low concentration (3%), you can safely use 1 g/cm³.
Who said that density of HCL solution is 1?


is my first calculation right???  
i just assume the density is near water.... 
Yes, Qing, your first calculation is right. Andre correctly pointed out that your second version just calculated the mass of the whole solution, water plus HCl.