# Standard solutions : I'm confusedWatch

Announcements
#1
In a book it says to make a standard solution you calculate the mass of sodium hydroxide needed in the solution. Then you place a weighing bottle on a digital balance and weigh out the required mass of solid approximately and tip it into a beaker.

You then weigh the weighing bottle and subtract the mass of the bottle from the mass of the bottle and the solid together to get the precise mass of the solid you weighed out.

My question is, wouldn't this mass be less than the one you wanted to measure out? Is there an error in the book?
Last edited by Mad Man; 3 weeks ago
0
3 weeks ago
#2
It doesn't matter if the precise mass of solute used is slightly less than desired, you can calculate the exact concentration of the solution using the precise value. This is fine in a school practical but in industry obviously a more accurate mass would be needed.
0
#3
(Original post by alannah66)
It doesn't matter if the precise mass of solute used is slightly less than desired, you can calculate the exact concentration of the solution using the precise value. This is fine in a school practical but in industry obviously a more accurate mass would be needed.
How is it exact if the mass isn't precise? Can't I just change the order in which I do it. So measure the mass of the weighing boat and THEN weigh out the mass of the solute ensuring that the mass isn't exceeded. For example if the weighing boat weighs 2 g ensure that you weigh 22 g of solute?
0
#4
bump
0
#5
Or can't you place the weighing boat on the balance, set it to zero and then add the solid?
0
#6
Hello? #
0
#7
I really need help here please.
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• Bournemouth University
Wed, 19 Feb '20
• Buckinghamshire New University
Wed, 19 Feb '20
• University of Warwick
Thu, 20 Feb '20

### Poll

Join the discussion

Yes (46)
31.08%
No (76)
51.35%
Don't know (26)
17.57%