[amorale]

What is the molarity of 70% TBHP? Given: d=0.937g/ml, FW=90.12g/mol, w/w%?

I am assuming that the density is of the 70% but not sure and idk what w/w% means.
But this is what I got

1000ml x (0.937g/ml) x (1mol/90.12g) = 10.4mol/L

Did I get it or am I missing that percentage part?

[Dan]

w/w% means weight percent, i.e. in every 100 g of solution, 70 g is TBHP.

Go in small logical steps rather than trying to throw it all into an equation.

You want to know mol/L, so...

1. What is the mass of 1 L of solution?
2. So what is the mass of TBHP in 1 L of solution?
3. How many moles of TBHP in 1 L of solution?

[Arkcon]

Well, w/w% means weight to weight percentage, as distinct from v/v% which would be volume to volume percentage.  If you know the definition of molarity, you can pick out what values you'll need to compute it, and you can see from the info you have, how to compute it.  You might also have to use the definition of density to help.  Now, while you're learning, its better to write things out in terms of what you have given, what you need to compute, to calculate the molarity.  Once you're good at it, you can save time by stringing them all into one formula like you've done.

[amorale]

Ok, I guess were I went wrong was assuming that the density given was the density of only TBHP.

So:

1000mL x (0.937g/mL) = 937g

937g x .7 = 655.9g

655.9g x (1mol/90.12g) = 7.28mol

and since this is in 1000ml or 1L

Molarity is 7.28M

Correct?

BTW thanks for advice

[Dan]

I agree

[grs35]

by using 70/90.12 you find the number of moles which is 0.77674...

M=n/V

v is the volume of the solution. we assume that we have 100 gr of the solution. if you convert it into mL you will find 106.7236 mL

plug them in the formula and don't forget to conver mL into L. The answer is 7.76 M

[Borek]

The answer is 7.76 M

It is not.

[Dan]

The answer is 7.76 M

No it isn't.

by using 70/90.12 you find the number of moles which is 0.77674...

M=n/V

v is the volume of the solution. we assume that we have 100 gr of the solution. if you convert it into mL you will find 106.7236 mL

plug them in the formula and don't forget to conver mL into L.

So:  M = 0.77674/106.7236
          = 7.28 (not 7.76)