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Topic: pH of Ba(OH)2 * 8 H2O  (Read 5994 times)

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Offline Edher

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pH of Ba(OH)2 * 8 H2O
« on: February 18, 2006, 07:19:17 PM »
Saludos,

      I'm having trouble understanding this problem:

Calculate [H3O]  and pH in saturated Ba(OH)2(aq), which contains 3.9g Ba(OH)2 * 8H2O per 100 mL of solution.  

( * means times)

The       * 8H2O is throwing me off. I don't know how to take it into account in the equation. Also, when finding the molarity of BaOH2 do I have to add the weight of 8 moles of water to the calculation?

Thank you for your time,
Edher
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Offline plu

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Re:pH of Ba(OH)2 * 8 H2O
« Reply #1 on: February 19, 2006, 12:36:42 PM »
The water molecules there are simply a part of the solid 3.9 grams that you are dissolving into solution (these kinds of solids are referred to as "hydrates").  When you calculate the moles of solid you are dissolving, you must take into account the water molecules as part of the molecular formula.  Other than that, the Ba(OH)2 is just another base.
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Offline Donaldson Tan

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Re:pH of Ba(OH)2 * 8 H2O
« Reply #2 on: February 25, 2006, 07:59:55 PM »
Quote from: Edher on February 18, 2006, 07:19:17 PM
. which contains 3.9g Ba(OH)2 * 8H2O

This is the formula of the salt crystal you used to dissolve. It tells in 1 mole of the crystallised Ba(OH)2. there is 8 moles of water and 1 mole of Ba(OH)2. The water in the chemical formula is known as the water of crystallisation.

the molar mass of Ba(OH)2* 8H2O
= molar mass of Ba(OH)2 + 8 x molar mass of water

« Last Edit: February 25, 2006, 08:00:14 PM by geodome »
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