"A student mixes four reagents together, thinking that the solutions will neutralize each other. The solutions mixed together are 50.0mL of 0.100M hydrochloric acid, 100.0mL of 0.200M of nitric acid, 500.0mL of 0.0100M calcium hydroxide, and 200.0 mL of 0.100M rubidium hydroxide. Is the resulting solution neutral? If not, calculate the concentration of excess H+ or OH- ions left in solution."
My problem is, I have no idea how to first set it up. Would I have to make additional reactions as I go through each acid and base in the solution? If not, what would I do? I can solve the problem once I figure out how to start it off, I just need a guideline to start it. Any help is appreciated, thank you.
2007-04-17 09:24:31 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Here are a few things I would consider:
I'd start with getting the formulas of the chemicals involved. For instance, I know that hydrochloric acid is HCl, so it has one mole of H+ per mole of acid.
Then I'd work out how many moles of each chemical had gone in. Take hydrochloric acid: 0.100M is 0.1 moles per litre. You have 50mL or 0.05 litres. Multiply the concentration by the volume, ie 0.1 x 0.05 = 0.005 moles.
Multiply the moles by the number of H+ ions ie. 1, and you have 0.005 moles of H+ ions.
Work out the number of moles of H+ ions and the number of moles of OH- ions. If the number is the same, the solution is neutral. The ions cancel each other out creating water.
If say, the result is that there are 0.04 moles of H+ ions and 0.06 moles of OH- ions, you would take away the number of H+ ions to give 0.02 moles OH- ions. Then add up all the volumes given and convert them to litres (Imagine it makes 0.2 litres). Then divide the number of moles by the volume (0.02/0.2 in this example) and you have the concentration in M (0.1 M in this example).
Hope this helps! It's really a lot of basic arithmetic but getting your head around all those different numbers can be tricky.
2007-04-17 09:57:04 · answer #1 · answered by Helen B 3 · 0⤊ 0⤋
Each acid you add to solution gives H+ on dissocation and each base gives OH-. To work the problem you need the total moles of H+ and total moles of OH-. If they are even it is a neutral solution, if more H+ acidic, and if more OH- basic.
To determine you can take the volume and molarity to determine moles:
mol = molarity x L
That will give you the amount of each compound, just remember that cacium hydroxide has 2 OH groups per molecule so you'll get twice as much.
2007-04-17 09:41:00 · answer #2 · answered by moneymonty 3 · 0⤊ 0⤋
Work out the total H+ ion moles. Both of the acids are monoprotic, so that is no problem. Then work out the total OH- ion moles - bearing in mind that there are 2 moles of OH- for every mole of calcium hydroxide. RbOH is simpler, of course.
Then just see which is larger than the other, and subtract.
2007-04-17 09:42:59 · answer #3 · answered by Gervald F 7 · 0⤊ 0⤋
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2016-05-17 09:56:13 · answer #4 · answered by ? 3 · 0⤊ 0⤋