chem5 - Experiment 8-Antacid Analysis Pre-Lab Questions: 1....

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Experiment 8-Antacid Analysis Pre-Lab Questions : 1. Hcl(aq) + NaOH(aq) > NaCl(aq) + H2O(l) 2. H+(aq) + OH-(aq) > H2O(l) 3. The equivalence point is when the moles of hydroxide ions are equal to the number of moles of hydrogen ions, that is [H+]=[OH-]. 4. The purpose of standardizing the NaOH is to make sure it is exactly 0.300 M. A .3 M NaOH from the storeroom may possible be inaccurate, which is why we start with 6M NaOH, then titrate it to the exact molarity. 5. There is just one acidic H+ in KHP because only one H+ is bonded to an oxygen. Protons are lost more when bonded to an electronegative ion, in this case it happens to be the oxygen. 6. The number of moles of OH- is equal to the number of moles of KHP at the equivalence point because there is one H+ per KHP molecule and therefore the concentration of KHP is equal to the concentration of H+. This means OH- is equal to the concentration of H+ which is equal to KHP, the equivalence point. 7. The solution must be stopped because NaOH slowly reacts with the CO2 in the air. 8. HA(aq) + OH-(aq) > H2O(l) + A-(aq) 9. HA(aq) + Noah > NaA + H2O 10. The equivalence point is where the moles of acid equal the moles of hydroxide ions. 11. A. K=[Ca2+][CO2-/3]/1 B. Solids are not included because they affect neither the concentration nor the pressure. 12. K=[HCO-3][OH-]/[CO2-/3] K=[H2CO3][OH-]/[HCO-3] 13. The equilibrium position is farther to the left. 14. A. CaCO3 is generally insoluble in water B. Antacid is dissolved in excess acid. After the antacid is dissolved, some acid is left over. This is titrated with a base until neutralized and then a measurement of the volume of base used tells us how much acid was left. Then we subtract the excess acid from the original amount of acid, giving us how much acid was consumed by the antacid,
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showing the neutralization capacity of the antacid. This gives the amount of CaCO3 used. 15.
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This note was uploaded on 09/30/2008 for the course CHEM 1A/1B taught by Professor Neuman during the Fall '06 term at UCSB.

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chem5 - Experiment 8-Antacid Analysis Pre-Lab Questions: 1....

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