Introduction to Acids Base chemistry
Introduction to Acids Base chemistry
Purpose
How to determine the constant equilibrium of an acid, Ka? How to evaluate the concentration (M) of an acid? In “part A” experiment, we would test the PH of different concentration of acetic acid (a weak acid which partially dissociated in water) with a PH probe. After we got the PH, we could find out the concentration of H+ by applying the relationship pH = -log [H+]. Having the determined value of [H+] of a weak acid with a known molar concentration [HA], The acid dissociation constant, Ka, can be determined according to Ka = [H+][A-] /[HA]. In “Part B” experiment, we use a strong acid (HCl) and a weak acid (acetic acid) titrates with a strong base (NaOH). In both titrations, we will monitor the change in PH to determine the volume of 0.100 M NaOH required neutralizing both 10ml sample of HCl and acetic acid. And refer to the neutralization reaction of these two acid, H+ (aq) + OH-(aq) → H2O(l) for HCl, and CH3COOH(aq) + OH-(aq) → CH3COO-(aq) + H2O(l) . as we can see , in both case, two reaction have 1:1 stoichiometry, the moles of NaOH added = moles of acid present in the 10.00 mL sample , this will allow to calculate the concentration of acid in the original sample.
Procedure
“Part A” experiment:
1. Prepare 100 ml of 0.020M acetic acid solution using the provided 2.00M acetic acid stock solution.
2. Use M1*V1 = M2V2 to calculate the volume require to make 100 ml of 0.020M acetic acid solution.
3. Pipet the required volume of 2.00M acetic acid stock solution into a 100-ml volumetric flask, add some (25-50 mL) distilled water and swirl to mix, then add enough distilled water to bring the total solution volume to the 100 mL mark. To prevent overshooting the mark, use a wash bottle filled with distilled water for the last few ml. Stopper the flask and invert several times to mix thoroughly.
4. Use a utility clamp to secure a PH Sensor to a ring stand.
5. Connect the probe with the computer interface,
Purpose
How to determine the constant equilibrium of an acid, Ka? How to evaluate the concentration (M) of an acid? In “part A” experiment, we would test the PH of different concentration of acetic acid (a weak acid which partially dissociated in water) with a PH probe. After we got the PH, we could find out the concentration of H+ by applying the relationship pH = -log [H+]. Having the determined value of [H+] of a weak acid with a known molar concentration [HA], The acid dissociation constant, Ka, can be determined according to Ka = [H+][A-] /[HA]. In “Part B” experiment, we use a strong acid (HCl) and a weak acid (acetic acid) titrates with a strong base (NaOH). In both titrations, we will monitor the change in PH to determine the volume of 0.100 M NaOH required neutralizing both 10ml sample of HCl and acetic acid. And refer to the neutralization reaction of these two acid, H+ (aq) + OH-(aq) → H2O(l) for HCl, and CH3COOH(aq) + OH-(aq) → CH3COO-(aq) + H2O(l) . as we can see , in both case, two reaction have 1:1 stoichiometry, the moles of NaOH added = moles of acid present in the 10.00 mL sample , this will allow to calculate the concentration of acid in the original sample.
Procedure
“Part A” experiment:
1. Prepare 100 ml of 0.020M acetic acid solution using the provided 2.00M acetic acid stock solution.
2. Use M1*V1 = M2V2 to calculate the volume require to make 100 ml of 0.020M acetic acid solution.
3. Pipet the required volume of 2.00M acetic acid stock solution into a 100-ml volumetric flask, add some (25-50 mL) distilled water and swirl to mix, then add enough distilled water to bring the total solution volume to the 100 mL mark. To prevent overshooting the mark, use a wash bottle filled with distilled water for the last few ml. Stopper the flask and invert several times to mix thoroughly.
4. Use a utility clamp to secure a PH Sensor to a ring stand.
5. Connect the probe with the computer interface,