# Thread: Chem - salt problem AJ

1. Hi, Can you help me on doing the steps to answer this problem?

Given:
Mass of Salt = 10 grams
Total Volume = 1 litres
--> the salt is dissolved into this volume to make a solution.
pH of the Solution = 13.07
--> salt is completely ionized in the solution.

Required: Molecular Weight of the salt.

Correct me: (given the mass; we need to find the number of mole)
Step 1 - find concentration using the pH.
pH = -log[A], where [A] is the concentration of the solution.
Step 2 - find the number of moles is the solution.
n (# of moles) = Volume (total volume) x Molarity (from step one)
Step 3 - find the molecular weight by dividing the mass by the number of moles.
MW (molecular weight) = mass divided by the # of moles.

2.

3. Hey, I got the correct steps and the right answer. Thanks anyways.

4. Yeah, i totalyl agree with the understanding better than memorizing.

The more you memorize, the more you forget and the more you will have a failuer in exam and wateva field.

I used to memorize all the science subject last time instead of understanding. I had alomost spent all the time and i had been very tired of the science subjects.

Pls...understand the subject before yuo really want to memorize it cos
understand gain 75%, and memorizing only gain 25%

understading + memorizing = 75% + 25%
= 100%

HAHAHA :wink:
cheers

5. LOL. Thanks for your comment.

Cheers!

6. Just in case someone has a similar problem.

The correction is in step 1. Since this is a basic solution, find the OH concentration (by using the fact that [H+][OH]=1x10^-14). Then apply this found concentration to the rest of the steps.

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