Bradley Trotter & John Fussell Chem 1121-42 March 29th, 2018 Identity of an Unknown Weak Acid Lab Report Introduction: Being able to determing the molar mass of an unknown solution is one of the many ways to identify what the unknown solution is. The use of titrations and LoggerPro, make extrapolating data more precise and will produce more accurate results than if done manually. By comparing the caculated molar mass, and pKa values, with accepted values a hypothesis can be made to the identity of that unknown. The molar mass and pKa value was found by using LoggerPro to make a titration curve. Applying the first derviative to the titration curve allows the extrapolation of the equvillance volume, which in turn is used to calculate the …show more content…
As the OH- from the base is steadily added to the acid, the pH will increase as the OH- anion reacts with the H3O+ cation to make H2O and excess OH-. This H2O and OH- production decreases the concentration of the H+ available in the solution and in turn raises the concentration of OH- and pH. When all of the H+ is neutralized, the exact volume of the base is called the equivalince volume and at that volume the solutions are stoicheometrically equivalent, allowing the calculation of molar mass. The exact concentrations of both the acid and base solutions must be calculated to get accurate …show more content…
A 0.2057 M stock solution of NaOH was added to the plastic syringe while the acidic solution was being made. 1.329 g of unknown acid P was weighed on the electronic scale and recorded. The unknown solid acid was placed into a 100 mL volumetric flask and filled to the line with a 0.1 M stock solution of KCl. The solution was agitated to aid in the dissolving of the solid acid solution. When the acid was completely dissolved 25 mL of distilled water was added to a clean 100 mL beaker, along with 25.00 mL of acidic solution using a volumetric pipette. The acidic solution containing beaker was placed underneath the calibrated drop counter and atop a stir plate as a stir bar was added, along with a pH probe. As the bottom stopcock was being turned, LoggerPro was turned on and started to record the titration curve. The titration curve was allowed to run for approximately 10 mL after the equviallance volume. The first derviative was determined in LoggerPro and recorded as the equvillance volume as well as the pH of 1/2 the equivallence volume. These steps were repeated for one addtional
Question3: Experiment 3 The unknown acid sample was 1 • Monoprotic Acid Trails Initial NaOH solution (mL) final NaOH solution (mL) The volume of NaOH to titrate the acid (mL) Amount of Unknown Acid sample 1 (g) The moles of the Unknown Acid (mol) Molar mass of the Unknown Acid (g/mol) A 3.38 28.31 24.93 0.150 0.0026 57.69 B 0.18 29.32 29.14 0.175 0.0029
Next, about 10 mL of both solutions, Red 40 and Blue 1, were added to a small beaker. The concentration of the stock solution were recorded, 52.1 ppm for Red 40 and 16.6 ppm for Blue 1. Then, using the volumetric pipette, 5 mL of each solution was transferred into a 10 mL volumetric flask, labelled either R1 or B1. Deionized water was added into the flask using a pipette until the solution level reached a line which indicated 10 mL. A cap for the flask was inserted and the flask was invented a few times to completely mix the solution. Then, the volumetric pipette was rinsed with fresh deionized water and
1. Identify the range of senses involved in communication • Sight (visual communication), Touch (tactile communication), Taste, Hearing (auditory communication), Smell (olfactory communication) 2. Identify the limited range of wavelengths and named parts of the electromagnetic spectrum detected by humans and compare this range with those of THREE other named vertebrates and TWO named invertebrates. Figure 1: the electromagnetic spectrum source: www.ces.fau.edu Vertebrates Human Japanese Dace Fish Rattlesnake Zebra Finch Part of electromagnetic spectrum detected ROYGBV (visible light) detected by light sensitive cells in the eye called rods and cones.
Lastly, the unknown compound was reacted with two different salts. For the first salt, 0.50 grams of KCl was mixed with 5 mL of water in one beaker while 0.5 grams of NaNO3 was mixed with 5 mL of water in a different beaker. Then, the NaNO3 solution was added to the KCl solution. To perform the reaction with the second salt, 0.50 grams of KCl was mixed with 5 mL of water and 1 mL of 1 M Ag(NO3)2 was added. After performing each reaction, the solution was observed to see if a reaction occurred and the pH value of the resulting solution was tested using a pH
A table to show the pH of certain solutions Solution Test 1 Test 2 Test 3 Average Distilled water 7.7 7.9 7.8 7.8 2.5 g NaHCO3 (Sodium bicarbonate) 8.1 8.3 8.3 8.2 10ml of 0.85% lactic acid 3.1 3.2 2.9 3.1 5g NaHCO3 (Sodium bicarbonate) 8.1 7.9 8 8 Dry ice 4 4.1 4.2 4.1 Solid NH4Cl 6 6.8 6.5 6.4 0.1M HCl 2.5 2.4 2.3 2.4 Compare the increase or decrease of pH in different solutions to the pH of the distilled water. According to the research done in the Literature Review, acidosis is usually caused by a buildup of lactic acid in the body due to muscle exertion.
Using the equation m = ΔTf/Kf , the molality of the unknown solution was found. Then, moles of unknown were calculated, which was used to calculate the average molar mass of unknown. Theory: After the experiment was completed, the data
I. Purpose: To experimentally determine the mass and the mole content of a measured sample. II. Materials: The materials used in this experiment a 50-mL beaker, 12 samples, a balance and paper towels. III.
Unknown A is Excedrin because they both look like white powders and they were both soluble. When the universal indicator was added they both turned red, which indicted their pH level was 4.0. Then when we tested the pH with the pH strips they both showed the pH as being 3.0. After that, we added HCl or stomach acid and both drugs dissolved and were soluble. We tested the pH and it dropped to 1.0.
Conclusion: Based on the results of molarity from Trials 1, 2, and 3, it is concluded that our experimental for each trial is .410M NaOH, .410M NaOH, and .450M NaOH. The actual molarity of the NaOH concentration used was found to be 1.5M NaOH. The percent error of the results resulted in 72%. The large error may have occurred due to over titration of the NaOH, as the color of the solution in the flask was a darker pink in comparison for the needed faint pink. Discussion of Theory:
Measure 10 ml of .5 M HCl (measure from meniscus) using a pipette into a clean dry measuring cylinder and pour into a clean 100 ml conical flask. Repeat step 5 and 6 for 1M and 2M HCL and keep all the acids ready away from working bench to avoid spills during experiment. Reset your stopwatch timer and prepare a gas delivery system including water bath as shown in apparatus below.
The equation of the reaction between sodium hydroxide and ethanoic acid is as follows: CH3COOH + NaOH → CH3COONa + H2O We can measure the end point of titration process and we can also measure the amount of reactants. The concentration of ethanoic acid in the vinegar can be determined through stoichiometric calculations, Using the values obtained from the titration, and also the chemical equation as a reference. Phenolphthalein indicator is used in this acid-base titration Equipment and materials:
Procedure A. Preparation of NaOH solution The molarity of a solution is the ratio of the number of solutes dissolved in a liter of solution. To figure out the needed mass (in grams) of NaOH pellets to be dissolved in a 0.25 L of water, remember that a mole is equivalent to the quotient of mass over the molar mass of the substance. This was used to rearrange the base formula and to derive the mathematical equation of mass in terms of molarity. mass (g) =
Strong acids and strong bases are strong electrolytes and are assumed to ionize completely in the presence of water. Weak acids however, only ionize to a limited extend in water. Any weak or strong acids when in contact with any weak or strong alkali will start to undergo neutralization regardless of their volume. When an indicator which is present in the acid-base mixture and have experienced colour change, it indicates that the mixture is in right proportions to neutralize each other and is also known as the equivalence point.
The chemical equation for this experiment is hydrochloric acid + sodium thiosulphate + deionised water (ranging from 25ml to 0ml in 5ml intervals) sodium chloride + deionised water (ranging from 25ml to 0ml in 5ml intervals) + sulphur dioxide + sulphur. As a scientific equation, this would be written out as, NA2S2O3 + 2HCL + H2O (ranging from 25ml to 0ml in
That caused a new initial reading of NaOH on the burette (see Table1 & 2). The drops were caused because the burette was not tightened enough at the bottom to avoid it from being hard to release the basic solution for titrating the acid. The volume of the acid used for each titration was 25ml. The volume of the solution was then calculated by subtracting the initial volume from the final volume. We then calculated the average volume at each temperature.