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Topic: Concentration Problems  (Read 4660 times)

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Offline xwrathbringerx

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Concentration Problems
« on: June 07, 2009, 01:15:55 AM »
Hey guys

Could someone please help me with these questions? I could do all the questions before these, which simply used the formula C = n/V and a little manipulation but I don't get how to apply the formula, etc. into these problems. :P Please help?

1. To determine the solubility of calcium hydroxide, a chemist took 25 mL of a saturated calcium hydroxide solution and found that it reacted completely with 8.13 mL of 0.102 mol/L hydrochloric acid. Calculate the molarity of the calcium hydroxide solution and the solubility of calcium hydroxide in g per litre.

2. A solution was made by dissolving 22.22 g of calcium chloride in enough water to make a 500 mL solution. This was then reacted with 0.5 mol/L sulfuric acid to produce insoluble calcium sulfate. Calculate the volume of sulfuric acid needed to react and the mass of calcium sulfate produced.

3. What mass of insoluble lead bromide is formed when 30 mL of 0.050 mol/L potassium bromide is added to an excess of lead nitrate solution.

4. 50 mL 0.20 mol/L sodium hydroxide was mixed with 50 mL 0.30 mol/L magnesium chloride. A precipitate of magnesium hydroxide was formed. Calculate the concentration of sodium ions, magnesium ions and chloride ions.

Thanx a lot!

Offline Borek

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Re: Concentration Problems
« Reply #1 on: June 07, 2009, 04:52:35 AM »
SUrely you must have some ideas, you just don't think they will work. Show them.

If you have completely no idea what to do, start with the reaction equation. Check what you can calculate using it.
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Offline xwrathbringerx

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Re: Concentration Problems
« Reply #2 on: June 07, 2009, 07:44:53 PM »
I seriously have no clue how the questions work  :-\

Offline Borek

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Re: Concentration Problems
« Reply #3 on: June 08, 2009, 03:03:07 AM »
Reaction equations. Pretty please... with sugar on top.
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Offline xwrathbringerx

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Re: Concentration Problems
« Reply #4 on: June 15, 2009, 04:00:07 AM »
Hi I've managed to solve the 1st 3. Could someone please help me with the fourth????

1. To determine the solubility of calcium hydroxide, a chemist took 25 mL of a saturated calcium hydroxide solution and found that it reacted completely with 8.13 mL of 0.102 mol/L hydrchloric acid. Calculate the molarity of the calcium hydroxide solution and the solubility of calcium hydroxide in g per litre.

2. A solution was made by dissolving 22.22 g of calcium chloride in enough water to make a 500 Ml solution. This was then reacted with 0.5 mol/L sulfuric acid to produce insoluble calcium sulfate. Calculate the volume of sulfuric acid needed to react and the mass of calcium sulfate produced.

3. What mass of insoluble lead bromide is formed when 30 mL of 0.050 mol/L potassium bromide is added to an excess of lead nitrate solution.


4. 50 mL 0.20 mol/L sodium hydroxide was mixed with 50 mL 0.30 mol/L magnesium chloride. A precipitate of magnesium hydroxide was formed. Calculate the concentration of sodium ions, magnesium ions and chloride ions.


Attempted Solution:

1. Write the balanced equation.

2. Calculate the no. of moles of sodium hydroxide.

3. Calculate the no. of moles of magnesium chloride.

4. ???

..

Please, any help???

Offline AWK

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Re: Concentration Problems
« Reply #5 on: June 15, 2009, 05:25:58 AM »
This is a problem with a limited reagent
AWK

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