Using a primary standard to analyze acid and base solutions Acid-base titration Lab 13G
Jake Shewchuk Lab 13C Dominique Genereux
Purpose 13G:
1. To prepare a standard solution of oxalic acid and use it to standardize an unknown sodium hydroxide solution.
Purpose 13C:
1. To titrate a hydrochloric acid solution of “unknown” concentration with standardized 0.5M sodium hydroxide.
2. To titrate a hydrochloric acid solution of “known” concentration with standardized 0.5M sodium hydroxide.
3. To titrate an acetic acid solution (vinegar) with standardized 0.5M sodium hydroxide.
4. To utilize the titration results to calculate the molarity of the hydrochloric acid and the
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% difference= (larger value - smaller value)/ (larger value + smaller value)/2 * 100%
% difference= (.5418M - .5225M)/ (.5418M+ .5225M)/2 * 100%
% difference=.91%
Follow up 13G:
1. The property of this acid solution (soft drink) overcome by using of sugar or artificial sweetener is the sourness. Most acids are sour so the sugar makes it sweeter in a soft drink, so it is more desirable to drink.
2. What mass concentrated HCl will be required required to neutralize the NaOH? NaOH moles n=C*v n=8.0x103L* .040M n=320 mols HCl moles =320 mols HCl volume v=n/C v=320 mols / 12M v=26.66666 HCl mass m=d*v m=1.2Kg/L / 26.66666 m=32Kg or 32000 g 3. Calculating the the percentage by mass of NaCO in the sample:
Moles of HCl n=C*v n=.500M*.0486L n=.0243mols Moles of NaOH n=m/MM n=1.00g/40.0 n=.0250mols 2HCl(aq) + Na2CO3 → 2NaCl(aq) + H2O(l) + CO2(g)
Moles of Na2CO3 n=m/MM n=1.00g/160.0 n= .0094339623moles .0243 (moles of HCl) = x * 0.01887 + (1.000 - x) * .0250 .0243 = .01887x + .0250 - .0250x
.00613x = .0007 x=0.114 Percentage of Na2CO3 by mass is 11%
4. It would be difficult to measure the concentration of acid in red wine or coca-cola because the colour of the drink is too dark for us to see when the phenolphthalein indicator changes colour. You could overcome this difficulty by using a pH meter.
5. Explaining why the conductivity reaches a minimum.
Ionic equation:
Ba2+(aq) + 2OH-(aq) + H+(aq)+ HSO4(aq) → BaSO4(s) + 2HOH(l)
At the neutralization
3.6.3. 2, 4 – D (2, 4–Dichloro phenoxy acetic acid) stock solution (1mg/ml): 10.0mg of 2.4-D being weighed and dissolved completely in 1N NaOH to a final total volume
We know that that the end point of the titration is reached when, after drop after careful drop of NaOH, the solution in the flask retains its pale pink color while swirling for about 30
2. Calculate the molarity of the Hydrochloric acid in the flask. You may refer to the Titration demo at the beginning of the honors lesson, just above the Virtual Lab to see sample calculations.
H. How would you prepare 10 mL of a 0.25M HCl solution if 1M HCl was available? How much
To determine the concentrations in both parts, the change in pH is monitored for every added amount of 0.1035 M NaOH. The pH of the solution is taken using the Orion Model 420A pH reader. The data for Figures 1-4 can be found in Appendix. B.
Chemistry 102 is the study of kinetics – equilibrium constant. When it comes to the study of acid-base, equilibrium constant plays an important role that tells how much of the H+ ion will be released into the solution. In this lab, the method of titrimetry was performed to determine the equivalent mass and dissociation constant of an unknown weak monoprotic acid. For a monoprotic acid, it is known that pH = pKa + log (Base/Acid). When a solution has the same amount of conjugate base and bronsted lowry acid, log (Base/Acid) = 0 and pH = pKa. By recording the pH value throughout the titration process and determining the pH at half- equivalence point, the value of Ka can be easily calculated. In this experiment, the standardized NaOH solution has a concentration of 0.09834 M. The satisfactory sample size of known B was 0.2117 g. The average equivalent mass of the unknown sample was found to be 85.01 g, pKa was found to be 4.69, which was also its pH at half-equivalence point and Ka was found to be 2.0439×〖10〗^(-5). The error was 1.255% for equivalent mass and 0.11% for Ka. In other word, the experiment was very precise and accurate; the identity of the unknown sample was determined to be trans-crotonic by the method of titrimetry.
During a titration the pH of the solution will be monitored using a pH meter from that we get a titration curve. The titration curve is then used to determine the equivalent molecular weight and Ka value of the unknown weak acid, from that we are
ii. The second part of the titration series involves titration of NaOH with Hydrochloric acid (HCL). Again, three reps of titration and a blank titration have to be completed. A volumetric pipet is used to measure 10.00mL of HCL into three labeled conical flasks. Then the flasks are filled with deionized water until about the 50mL mark. A buret is
Using Graph 1: The Volume of Titrant Added in order to reach the Endpoint and the Corresponding pH Values, observe the vertical line of each titration and see the points in which the horizontal lines intersect it. These points give the
An example would be pure water. Most of the time the pH is determined by pH paper but there are also other ways to determine the pH. For example, in this lab, cabbage juice was used. Cabbage juice is a great pH indicator because it can be homemade and easy to access.
An acid-base titration is the determination of the concentration of an acid or base by exactly neutralizing the acid/base with an acid or base of known concentration. This allows for quantitative analysis of the concentration of an unknown acid
In this experiment, a redox reaction occurred. An oxidation-reduction reaction (redox) is a type of chemical reaction that involves a transfer of electrons between two solutions. The chemical being oxidized is losing electrons and the chemical being reduced is gaining electrons. In this case KMnO4 is losing electrons and Oxalic Acid is gaining electrons. KMnO4 can titrate a or reduce Oxalic acid. Titration is the technique used to find the unknown concentration of one solution based on the concentration of a known solution. In equation 2, the molar relationship between the 2 is shown, it is 2 KMnO4 to 5 Oxalic Acid. The molar ratio relationship is useful because it shows how much of a certain product is needed to help a reaction occur and which chemical is limiting reagent. The experiment was started by preparing a titrating strength KMnO4 solution from stock to a less concentrated KMnO4. Equation one shows how this was done. The KMnO4 needed to be diluted, if it had not been diluted, then it would be way too hard to get an accurate reading of the Oxalic Acid used. Without being diluted the Oxalic Acid would be strong. The next step was to standardize the KMnO4 solution. It was calculated that 37.5 mL of Oxalic Acid could titrate 15 mL of KMnO4. To determine the exact molarity of a solution a standardization needs to happen. In this experiment the standardization found how much Oxalic acid was needed. Through the controlled variable, the fact that 37.5 Oxalic acid could be titrated by 15 mL of KMnO4, the percent of the
6. This solution is added to the conical flask containing the potassium iodate solution and it is immediately titrated with the sodium
To be able to standardize Sodium Hydroxide (NaOH) solution using a standard solution of Oxalic acid.
At the initial point, no titrant has been added yet and the solution’s pH equates to the number of H+ ions originally present in the analyte.