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Topic: AMS help  (Read 2875 times)

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Offline emishere96

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AMS help
« on: March 07, 2013, 07:52:06 AM »
Two different samples of sodium carbonate are contaminated with sodium hydrogencarbonate and sodium hydroxide respectively.

(a) 20.0㎤ of a solution containing sodium hydroxide and sodium carbonate required 19.20㎤ of 0.500mol dm-3 HCl with phenolphthalein as indicator, forming sodium hydrogencarbonate in the process. With methyl orange, a further 5.10㎤ of the acid was needed to complete the neutralisation of sodium hydrogencarbonate into carbon dioxide and water.

(i) Construct 3 balanced chemical equations for the reactions that occured in the experiment.
(ii) Calculate the concentration of each compound in the original solution.


here's what i did for part (a) (i), the three balanced chemical equations i came up with are
 1. Na2CO3 + 2HCl -> 2NaCl +CO2 + H2O
 2. NaOH + HCl -> NaCl + H2O
 3. NaHCO3 + HCl -> NaCl + H2O + CO2

I need to know if these equations are right, so as to continue attempting the second part of the question .  :)

Also, I don't quite understand how sodium hydroxide, sodium carbonate and HCl forms sodium hydrogencarbonate...
« Last Edit: March 07, 2013, 09:45:35 AM by emishere96 »

Offline sjb

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Re: AMS help
« Reply #1 on: March 07, 2013, 08:17:39 AM »
Two different samples of sodium carbonate are contaminated with sodium hydrogencarbonate and sodium hydroxide respectively.

(a) 20.0cm3 of a solution containing sodium hydroxide and sodium carbonate required 19.20cm3 of 0.500mol dm-3 HCl with phenolphthalein as indicator, forming sodium hydrogencarbonate in the process. With methyl orange, a further 5.10cm3 of the acid was needed to complete the neutralisation of sodium hydrogencarbonate into carbon dioxide and water.

(i) Construct 3 balanced chemical equations for the reactions that occured in the experiment.
(ii) Calculate the concentration of each compound in the original solution.

(b) A sample of anhydrous sodium carbonate contaminated with sodium hydrogencarbonate was made up to 250cm3 of solution. 25.0m3 of this solution required 11.20cm3 of 1.00mol dm-3 HCl with phenolphthalein as indicator and 24.50cm3 of the same acid with methyl orange as indicator.

(i) Calculate the concentration of sodium carbonate in the solution mixture.
(ii) Hence, calculate the mass of sodium carbonate in the sample
(iii) Calculate the percentage by mass of sodium hydrogencarbonate in the mixture

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Offline emishere96

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Re: AMS help
« Reply #2 on: March 07, 2013, 09:39:49 AM »
here's what i did for part (a) (i), the three balanced chemical equations i came up with are
 1. Na2CO3 + 2HCl -> 2NaCl +CO2 + H2O
 2. NaOH + HCl -> NaCl + H2O
 3. NaHCO3 + HCl -> NaCl + H2O + CO2

I need to know if these equations are right, so as to continue attempting the second part of the question  :)

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