Explain why one is essentially the same as the other. (2) 8. Determine the conjugate acid-base pairs in the following reactions: (Use 2 lines to connect the 2 pairs in each reaction.) (3) a. NH3(aq) + H2O(l) ↔ NH4+(aq) + OH-(aq) (base)NH3 and (acid)NH4+ OH- and H2O b. HNO2(aq) + H2O(l) ↔ H3O+(aq) + NO2-(aq) H2O and H3O+ NO2 and HNO2 c. HCN(aq) + H2O(l) ↔ H3O+(aq) + CN-(aq) CN and HCN H2O and H3O+ 9. How is the formula of a conjugate acid similar to its conjugate base, and how is it different?
. . 3 Quantitative treatment of acid-base equilibria 3.1 Strong acids and bases . . .
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.
4. Chlorine, Cl 2, is a strong oxidizing agent found in bleach. 10.0 cm3 of bleach solution was added to 25.0 cm3 of 0.4M Sn2+ solution acidified with sulphuric acid and made up to 100 cm3. 10.0 cm3 of the resulting solution containing the unreacted Sn2+ was titrated against 0.02M K2Cr2O7. Given that 11.40 cm3 of K2Cr2O7 was required for complete oxidation, a) Calculate the numbers of moles of Cr2O7- used.
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
This is because the less electronegative sodium has a weak Na-O bond and the oxygen is more easily given up to reacts with H+. Further along though, a strong S-O bond keeps this together and more H+ is generated. The amphoteric aluminium oxide has a bonding which is both ionic and covalent in nature. When these oxides are reacted with acids or bases, a neutralisation would occur with a salt and water produced. Aluminium oxide is amphoteric, meaning it react with both acid and
After 10 seconds, the colorless mixture suddenly turns blue. Concept: Demonstrates a typical clock reaction; shows the effect of the interaction between chemical reactions that have different rates. Materials: • Solution A o 0.6 grams Starch o 30 mLs of Acetic Acid o 4.1 grams of Sodium Acetate o 50 grams of Potassium Iodide o 4.7 grams of Sodium Thiosulfate ▪ Allow mixture to cool and dilute to 1 liter with distilled water o 1 liter flask • Solution B o 500 mLs of 3% Hydrogen Peroxide o 500 mLs of distilled water o 1 liter flask o Safety: Hydrogen Peroxide can be irritating to skin and eyes. Wear safety goggles and gloves. Procedure: Mix the two solutions together.
Acid-Base Indicator Properties of Methyl Orange [pic] Procedure Pretreatment before Diazotization 1. Dissolve 1.2 g anhydrous Na2CO3 with 50 ml DI H2O
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). Determination of peroxide value. Weigh 3.00 g oil (with precision of 0.001 g) into a 250 ml Erlenmeyer flask. Add 10 ml chloroform and swirl to dissolve oil. Add 15 ml acetic acid,
I2 is the only species that is undergoing distribution. KI3 and KI are insoluble in the non-polar solvent as they are ionic. The concentration of I2 is related to its KD, or characteristic distribution coefficient. The concentration of I2 in the aqueous layer can be determined by measuring the I2 concentration in the organic layer as long as there is knowledge of KD. the total titratable iodide that was present is greater than the concentration of the I2 in the aqueous phase as some is being bound as I3-.