Add 0.5 ml concentrated HCl and 1.0 ml 15% KI solution. Mixed exactly 1 minute and leave for 5 minutes in a dark place. Add 0.5 ml starch solution, 20 ml distilled water. Mix and titrate with sodium thiosufate solution. Calculate the exact normality of Na2S2O3 knowing that in this chemical reaction 1 gram-equivalent of K2Cr2O7 react with 1 gram-equivalent of Na2S2O3 (1 mole K2Cr2O7 react with 6 moles Na2S2O3).
The apparent reaction rate was calculated using the equation, kapp= (1/∆t) x ([S2O32-]/[S2O82-]) which resulted in apparent rate constants of 5.66 x 10-5 s-1, 6.1958 x 10-5 s-1, 6.0356 x 10-5 s-1. The actual concentration was calculated using the basic chemical equation, C1V1 = C2V2. In order to find the order of reaction a a graph of log rate vs. log [S2O82-] was drawn, and was found that the results gave a zero order reaction But in reality the reaction order in [I-] and [S2O82-] is in first order each, although [I-] is kept at a constant volume throughout the reaction therefore the overall reaction is pseudo- first order. -d [S2O82-] = kapp [S2O82-] Dt In the second part the rate constant was found using the equation k = (1/∆t) x ([S2O32- ]/[Iodine][S2O82-]). Where it resulted to values of 3.990602 x 10-3 s-1, 4.653278 x 10-3 s-1, 5.944044 x 10-3 s-1, 7.499958 x 10-3 s-1, 7.499958 x 10-3 s-1, 9.84554 x 10-3 s-1, for flasks 4, 5, 6, 7, 8.
In each trial, the initial reading, final reading and the volume of HCl used was recorded down as quantitative results. The average volume of hydrochloric acid was found to be 12.03mL. The amount of sodium carbonate in the 10.00ml of solution was found to b 0.05 mol. The amount of hydrogen chloride that was dissolved in the average volume of acid is 0.365g. Through these calculations, the concentration of hydrochloric acid was found to be 8.3 mol•L-1.
Part I: Density of Unknown Liquid | | Trial 1 | Trial 2 | Trial 3 | Mass of Empty 10 mL graduated cylinder (grams) | 26.10 | 26.15 | 26.05 | Volume of liquid (milliliters) | 8.69 | 8.50 | 8.31 | Mass of graduated cylinder and liquid (grams) | 37.00 | 36.70 | 36.10 | Part II: Density of Irregular-Shaped Solid | Mass of solid (grams) | 38.954 | 39.068 | 42.885 | Volume of water (milliliters) | 49.9 | 49.9 | 50.0 | Volume of water and solid (milliliters) | 54.1 | 54.1 | 55.0 | Part III: Density of Regular-Shaped Solid | Mass of solid (grams) | 27.50 | 26.70 | 27.40 | Length of solid (centimeters) | 5.25 | 5.00 | 4.50 | Width of solid (centimeters) | 3.00 | 4.00 | 3.50 | Height of solid (centimeters) | 2.50 | 3.00 | 2.00 | Calculations Show all of your work for each of the following calculations and be careful to follow significant figure rules in each calculation. Part I: Density of Unknown Liquid 1. Calculate the mass of the liquid for each trial. (Subtract the mass of the empty graduated cylinder from the mass of the graduated cylinder with liquid.) * Trial 1 37.00(g) – 26.10(g) = 10.90(g) * Trial 2 36.70(g) – 26.15(g) = 10.55(g) * Trial 3 36.10(g) – 26.05(g) = 10.05(g) 2.
We are looking to find wether the reaction is exothermic or endothermic. Experiment 2: the aim for this experiment is to record the pH level of a sodium hydroxide and hydrochloric acid reaction. Then record it into the graph, it should resemble the standard neutralization curve, as shown under the introduction. Materials: what you will need for both experiments: Experiment 1: ➢ 20g baking soda ➢ 20g citric acid ➢ 2 cm strip of magnesium ➢ 50 ml of 5M HCl acid ➢ 50 ml measuring cylinder ➢
Titration Lab Period 3 5/20/12 Objective: The main objective of this lab was to determine the amount of sodium hydroxide needed to neutralize 10 milliliters of hydrochloric acid. We also had to calculate the molarity of the sodium hydroxide using our data. Concepts: Some different concepts used in this lab: indicators, titration formula, titration curves, pH levels, acids, and bases. Materials: Materials used in this lab: a 250mL beaker, ring stand, burette, Erlenmeyer flask, stop cock, burette clamp, 10mL HCL, 10mL NaOH, 3 drops of phenolphthalein, and pH paper. Procedure: 1.
The Ka expression, Ka=H+In-HIn [1] (1) is the equilibrium for the dissociation of the weak acid, where HIn is the acid and In- is the conjugate base. This is represented by the chemical equation: HIn ⇌H++ In- [1]Figure 1: Chemical equation for the dissociation of an acid-base indicator. Methyl red is a monoprotic organic acid. Figure 2 is a structural model of methyl red. Figure 2: Chemical structure of methyl red By plotting the data as the pH versus the log term of the Henderson-Hasselbach Equation, pH=pKa+logIn-HIn [2] (2) the pKa was
After the measurement is done, a linear graph of the signal data against analyte concentration is plotted. The concentration of the unknown sample is then determined using the equation of the calibration curve. Data Collection: (i) Concentration of benzene (% volume) 5 10 20 30 40 60 70 80 Benzene /chloroform mixture Volume of benzene added 0.5 mL 1 mL 2 mL 3 mL 4 mL 6 mL 7 mL 8 mL Wave number(cm1) 1586.712262 1586.712262 1586.712262 1586.712262 1586.712262 1586.712262 1586.712262 1586.712262 Peak counts 62.9508 48.53701 107.7373 137.6723 183.4448 279.8358 360.6083 392.8723 Concentration Volume of of chlorine (% chloroform volume) added 95 90 80 70 60 40 30 20 9.5 mL 9 mL 8 mL 7 mL 6 mL 4 mL 3 mL 2 mL Wave number(cm1) 760.5276014 760.5276014 760.5276014 760.5276014 760.5276014 760.5276014 760.5276014 760.5276014 Peak counts 854.4691 629.294 742.5334 655.9348 613.8774 440.0543 374.7844 270.9479 Unknown benzene/chloroform sample wave number (cm-1) peak counts 1586.712262 293.2169 760.5276014 431.0592 (ii) Ethanol Concentration of ethanol (% volume) 10 15 20 30 40 50 60 70 80 Volume of ethanol added 1.0 mL 1.5 mL 2.0 mL 3.0 mL 4.0 mL 5.0 mL 6.0 mL 7.0 mL 8.0 mL Volume of water added 9.0 mL 8.5 mL 8.0 mL 7.0 mL 6.0
Acid Base Titration Purpose: The purpose is to calculate the molarity of a NaOH solution by titrating the base with 5mL of standard HCl solution in each trial. By adding the base with unknown molarity to the acid with 0.10M the molarity of NaOH can be calculated. The base, NaOH, helps bring the pH of the acid, HCl, closer to seven, which neutralizes it. When using the buret the amount of NaOH used is able to be determined. Then by writing a balanced chemical equation and using the titration formula, Nb+Ma+Va=Na+MbVb , the molarity is able to be determined.
=n (mol)/v (dm3) Whereby c=concentration, n=number of moles and v=volume used. (JOHN GREEN AND SADRU DAMJI, PG 27.THIRD EDITION) Volume=0.1dm3 Concentration of acid =0.0048996mol/0.1dm3 =0.049moldm⁻3 Also, to calculate for the average titre volume of the acid used, I summed up the three consistent values from my experiment and divided it by 3(sarps series, 2009) thus Average Titre volume= (19.60+19.60+19.60) 3 =19.60cm3 Also, to calculate for the concentration of sodium hydroxide, I used The dilution factor, C₁v₁=C₂v₂ (JOHN GREEN AND SADRU DAMJI pg28, third edition) whereby C₁=concentration of the acid used=0.049moldm⁻3 v₁=volume of acid used (titre volume) =19.60cm3 C₂=concentration of the base, v₂=volume of the base used=10cm3 Therefore C₂=