Analysis of antacids Total NaOH 39.45 mL Total Hcl 99.70mL , mole of HCl were ad

Question

Analysis of antacids

Total NaOH 39.45 mL

Total Hcl 99.70mL , mole of HCl were added 0.000982 moles ,moles of NaOH were added 0.00404moles,Hcl React with NaOH 0.00404,Hcl React with sodium carbonate 0.00578mole, Sodium Carbonat React with HCl2.89*10^-5 mole,mole of Carbonate =1 mole,Mass of CO3^-2 =1.74g,the % bymass of carbonate 22.8%

Analysis of antacids Total NaOH 39.45 mL Total Hcl 99.70mL , mole of HCl were added 0.000982 moles ,moles of NaOH were added 0.00404moles,Hcl React with NaOH 0.00404,Hcl React with sodium carbonate 0.00578mole, Sodium Carbonat React with HCl2.89*10^-5 mole,mole of Carbonate =1 mole,Mass of CO3^-2 =1.74g,the % bymass of carbonate 22.8% 2. In the prelab exercises you determined the percent by mass of carbonate in sodium carbonate (Na2CO3). Explain how this information could be used to prove that the antacid tablet is not pure sodium carbonate. Be specific, Conclusion (Write a paragraph about the lab include briefly what was done, your result, Were you correct and possible experimental errors - (do not just state human and measurement errors as errors. Be specific, which human, which measurement...) Discussion: 1. What was the purpose of adding excess HCl to dissolve the antacid tablet, thus Overtitrating the carbonate ion, and how did you know when excess HCl had been added? Be specific; generalized answers will not receive credit.

Explanation / Answer

1. The purpose of adding excess HCl was to to decompose all Carbonate into CO2

CO32- +2H+ ===>H2O + CO2

and we back titrate the amount of HCl which has been left with the help of NaOH.

this gives us the moles of HCl which gives us amount of Carbonate in the sample.

(2moles of HCl are required to neutralize 1mole of Carbonate)

now from the moles of carbonate we determine its mass by multiplying it with its molar mass

we can have an idea from the bubbles of CO2 being liberated from solution. if no more CO2 bubbles are coming out its mean that no more carbonate and excess HCl has been added

2.

we can determine the amount of sodium carbonate from carbonate amount since 1mole of carbonate may contain only 2moles of sodium. if total amount of sodium and carbonate does't comply with each other i.e if carbonate moles are more than half moles of sodium then carbonate might be present in some other form than sodium

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