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# Mole calculation need help

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1. Hi, could I get some help with Q3 pls? I have answered all 3 parts of the question and need some checking pls! For c, what would be the volume of Sr(OH)2 ? I got 2 answers, one is using the v of h2o and one is using the volume of water and the metal. Thanks!
2. I am not sure about my answers so any help would be amazing... Thanks.
3. Just a guess, but maybe the volume could be 0.25dm3 (water) - vol of hydrogen?
Which would be 0.07527... I think :/
4. (Original post by coconut64)
I am not sure about my answers so any help would be amazing... Thanks.

Same
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5. (Original post by surina16)
Just a guess, but maybe the volume could be 0.25dm3 (water) - vol of hydrogen?
Which would be 0.07527... I think :/
I thought it would be the total volume of the reactants since sr dissolves in water... no?
6. (Original post by TeachChemistry)
Same
Hi, thanks so much for helping. But could you pls explain why the volume of sr(oh)2 is the same as water not the total volume of the metal and the water? The metal dissolves in the water, why isn't the volume of the metal considered ? Thanks
7. (Original post by coconut64)
Hi, thanks so much for helping. But could you pls explain why the volume of sr(oh)2 is the same as water not the total volume of the metal and the water? The metal dissolves in the water, why isn't the volume of the metal considered ? Thanks
Metal vol insignificant.
8. (Original post by TeachChemistry)
Metal vol insignificant.
Why?
9. (Original post by coconut64)
Why?
Think about what you actually have left at the end of the reaction.

250 g (or cm3 assuming a density of water of 1 g/cm3) of water minus 0.25 g of water that reacted with the strontium plus 0.86 g of strontium hydroxide now present. Density of final solution is not going to be a million miles away from density of pure water.

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