scholarly journals Do We Really Need the Concentration and Volume of a Solution of a Weak Acid to Calculate the Percentage Ionization or Degree of Ionization?

2021 ◽  
Vol 9 (2) ◽  
pp. 64-67
Author(s):  
R. Sanjeev ◽  
P. Sreedhar ◽  
V. Jagannadham
Keyword(s):  
Weak Acid ◽  
Degree Of Ionization

scholarly journals Analisis Kemampuan Berpikir Kritis Siswa Kelas XI MIA2 SMA Negeri 1 Masamba melalui Model Pembelajaran Berbasis Masalah pada Materi Pokok Asam Basa

2019 ◽  
Vol 19 (2) ◽  
pp. 167
Author(s):  
Nurul Hidayah ◽  
Halimah Husain ◽  
Netti Herawaty
Keyword(s):  
Critical Thinking ◽  
Problem Based Learning ◽  
Strong Acid ◽  
Thinking Skills ◽  
Weak Acid ◽  
Critical Thinking Skills ◽  
Thinking Skill ◽  
Critical Thinking Skill ◽  
Acid Base ◽  
Degree Of Ionization

ABSTRAK Penelitian deskriptif ini bertujuan untuk mengetahui bagaimana kemampuan berpikir kritis siswa melalui model Pembelajaran Berbasis Masalah pada siswa kelas XI MIA2 SMA Negeri 1 Masamba pada materi pokok asam basa. Subjek penelitian ini adalah siswa kelas XI MIA2 yang berjumlah 29 orang. Data hasil penelitian diperoleh dari hasil observasi selama proses pembelajaran untuk mengetahui kemampuan berpikir kritis proses dan nilai tes hasil belajar untuk mengetahui kemampuan berpikir kritis produk. Disimpulkan bahwa rata-rata kemampuan berpikir kritis proses siswa adalah 67,24% dikategorikan tinggi, dengan rincian indikator: 1) memberikan penjelasan sederhana sebesar 73,45% 2) membangun keterampilan dasar sebesar 70,34% 3) menyimpulkan sebesar 67,76% 4) memberikan penjelasan lanjut sebesar 63,97%, dan 5) mengatur strategi dan taktik sebesar 60,69%. Sedangkan rata-rata kemampuan berpikir kritis produk siswa adalah 26,94% dikategorikan sangat rendah. Persentase pencapaian siswa pada setiap indikator pembelajaran dengan materi asam basa yaitu: 1) menganalisis teori asam basa berdasarkan konsep Arrhenius, Bronsted Lowry dan Lewis adalah 36.25%, 2) menganalisis indikator yang dapat digunakan untuk membedakan asam basa adalah 70.94%, 3) memprediksi pH larutan dengan menggunakan beberapa indikator adalah 46.98%), 4) menghitung pH larutan asam/basa kuat dan asam/basa lemah adalah 22.13%, dan 5) menghubungkan asam/basa lemah dengan asam/basa kuat untuk mendapatkan derajat ionisasi (α) atau tetapan ionisasi adalah 7.50%. Kata kunci: Pembelajaran berbasis masalah, Berpikir kritis, Asam Basa ABSTRACT The aim of this deskriptif research is to determine how Student’s Critical Thinking Skill by Using Problem Based Learning Model to Students of Class XI MIA2 SMAN 1 Masamba in Material of Acid-Base. The subject of this research were students of XI MIA2 the counsist 29 studensts. The data was obtained by observation during the learning to know critical thinking skill of process and student’s learning achievement is to know critical thinking skill of product. It was concluded that the average critical thinking ability process of the students is 67.24% and categorized as high. Percentage of critical thinking process are: 1) elementary clarification indicator is 73,45%, 2) basic support indicator is 70,34%, 3) inferences indicator is 67,76%, 4) advance and clarification indicator is 63,97%, 5) and strategy and tactic indicator is 60,93% while the average product of students' critical thinking skills are 26,94% and categorized as very low. The percentage of student achievement on each indicator learning materials acid-base are: 1) indicator to analyze the theory of acids and bases is based on the concept of Arrhenius, Bronsted Lowry and Lewis was 36.25%, 2) indicators analyzing indicators that can be used to distinguish acid-base is 70.94%, 3) indicator predicts the pH of the solution using several indicators are 46.98%), 4) indicator calculates pH of strong acid/base and weak acid/base is 22.13%, and 5) indicators linking the weak acid/base with strong acid/base to obtain the degree of ionization (α) or constant ionization is 7.50%. Keywords: Problem based learning, Critical thinking, Acid-Base

Titration curves of fulvic acid: the analytical chemistry of a weak acid polyelectrolyte

1970 ◽  
Vol 48 (17) ◽  
pp. 2662-2669 ◽  
Author(s):  
Donald S. Gamble
Keyword(s):  
Molecular Weight ◽  
Fulvic Acid ◽  
Weight Fraction ◽  
Weak Acid ◽  
Low Molecular Weight ◽  
Ionization Equilibrium ◽  
Degree Of Ionization ◽  
Oh Groups ◽  
Titration Curves ◽  
Phenolic Oh Groups

The fulvic acid molecular weight fraction studied has two general types of carboxyl groups, one of which is ortho to phenolic —OH groups. The number of each type per gram of fulvic acid has been measured. The acid ionization equilibrium of each type has been calculated as a function of its degree of ionization in 0.1 m KCl at 25.0 °C. In both cases the acid strength decreases with increasing degree of ionization. The sample used shows the potentiometric titration behavior expected of a low molecular weight polyelectrolyte.

Henderson Hasselbalch Relationship and Weak Acid Titration

2019 ◽  
Author(s):  
Marc Blétry
Keyword(s):  
Theoretical Framework ◽  
Weak Acid ◽  
Acid Base ◽  
Sensitive Technique ◽  
Chemistry Students ◽  
Advanced Students ◽  
Acid Titration ◽  
Acid Base Titration ◽  
Analytical Expressions

Henderson-Hasselbalch relation is generally the simplified theoretical framework used to introduce students to acid-base titration. However, it is not always valid and its limitations should be made clear to chemistry students. The appropriate parameter to evaluate its validity is K a /C 0 , in connection with Ostwald dilution law. For more advanced students, it is possible to deduce analytical expressions that always fit accurately acid-base titrations and allow an evaluation of Henderson Hasselbalch relation. Gran plot appears as a particularly sensitive technique to the breakdown of Henderson Hasselbalch relation.

Use of Low Pressure Mercury Lamps for the Photodecomposition of Iron Cyanide in Gold Mill Effluents

1985 ◽  
Vol 20 (2) ◽  
pp. 111-119 ◽  
Author(s):  
J.H. Carey ◽  
S.A. Zaidi
Keyword(s):  
Ultraviolet Light ◽  
High Intensity ◽  
Experimental Evaluation ◽  
Low Pressure ◽  
Pilot Scale ◽  
Weak Acid ◽  
Potassium Ferricyanide ◽  
Technical Feasibility ◽  
Iron Cyanide ◽  
Scale Test

Abstract The use of ultraviolet light (UV) from low pressure mercury lamps for destroying iron cyanide in synthetic and actual gold mill effluents was evaluated in this study. For the light intensities used in this study, UV irradiation was not able to efficiently destroy cyanide. However, it converted iron cyanide to a weak acid dissociable form which was destroyed by chlorine. Data from several bench-scale tests and one pilot scale test were used to estimate quantum efficiencies (moles iron cyanide destroyed/einstein). These efficiencies ranged from 0.2% to 1%; approximately 30% to 90% lower than those reported in the literature for potassium ferricyanide. The data collected during the study demonstrated the technical feasibility of using UV in conjunction with chlorination for destroying iron cyanide in gold mill effluents. However, low pressure mercury lamps do not appear to be a practical UV source for this purpose. Irradiation with high intensity lamps may be more practical and is recommended for experimental evaluation.

Micellization Behaviour of Cationic Surfactants in the Presence of Food Additives: Conductance and Spectroscopic Investigations

2020 ◽  
Vol 10 ◽  
Author(s):  
Sonika Arti ◽  
Neha Aggarwal
Keyword(s):  
Glutamic Acid ◽  
Cationic Surfactants ◽  
Hydrophobic Interactions ◽  
Food Additives ◽  
Specific Conductance ◽  
Food Additive ◽  
Nmr Studies ◽  
Degree Of Ionization ◽  
Increase With Increase ◽  
Micellization Process

Aim: The micellization behavior of cationic surfactants have been studied in the presence of food additives. Objectives: Micellization behaviour of cationic surfactants, cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) has been studied in water and in various concentrations of salts (food additives) L-glutamic acid, sodium propionate, sodium citrate tribasic dihydrate and disodium tartrate dihydrate at (298.15, 308.15 and 318.15) K. Methods: Two methods used in the present study are specific conductance measurements and spectroscopy (NMR) studies. Results: From the specific conductance(κ), various parameters such as critical micelle concentration (CMC), degree of ionization of micelle (α), standard Gibbs free energy (ΔGom), enthalpy (ΔHom), and entropy (ΔSom) of micellization have also been calculated. Thermodynamic parameters related to the micellization process were also analyzed through NMR studies. Conclusion: The CMC values are influenced by the presence of food additive. The magnitude of CMC values increase with increase in concentration of food additive. In all the cases, enthalpy of micellization, ∆Hom values are found to be negative whereas entropy of micellization, ∆S om values are positive which indicate that hydrophobic interactions play a major role in the micellization process. Also, NMR studies reveal that tartrate and citrate are more hydrated than glutamic acid and propionate, resulting in more downfield shift.

Total weak acid concentration and effective dissociation constant of nonvolatile buffers in human plasma

2001 ◽  
Vol 91 (3) ◽  
pp. 1364-1371 ◽  
Author(s):  
Peter D. Constable
Keyword(s):  
Dissociation Constant ◽  
Human Plasma ◽  
Total Concentration ◽  
Weak Acid ◽  
Strong Ion Difference ◽  
Acid Base ◽  
Horse Plasma ◽  
Using Data ◽  
Species Specific

The strong ion approach provides a quantitative physicochemical method for describing the mechanism for an acid-base disturbance. The approach requires species-specific values for the total concentration of plasma nonvolatile buffers (Atot) and the effective dissociation constant for plasma nonvolatile buffers ( K a), but these values have not been determined for human plasma. Accordingly, the purpose of this study was to calculate accurate Atot and K a values using data obtained from in vitro strong ion titration and CO2tonometry. The calculated values for Atot (24.1 mmol/l) and K a (1.05 × 10−7) were significantly ( P < 0.05) different from the experimentally determined values for horse plasma and differed from the empirically assumed values for human plasma (Atot = 19.0 meq/l and K a = 3.0 × 10−7). The derivatives of pH with respect to the three independent variables [strong ion difference (SID), Pco 2, and Atot] of the strong ion approach were calculated as follows: [Formula: see text] [Formula: see text], [Formula: see text]where S is solubility of CO2 in plasma. The derivatives provide a useful method for calculating the effect of independent changes in SID+, Pco 2, and Atot on plasma pH. The calculated values for Atot and K a should facilitate application of the strong ion approach to acid-base disturbances in humans.

Deep Eutectic Solvents with Multiple Weak Acid Sites for Highly Efficient, Reversible and Selective Absorption of Ammonia

2021 ◽  
pp. 118791
Author(s):  
Ning-Ning Cheng ◽  
Zi-Liang Li ◽  
Hong-Chao Lan ◽  
Wen-Long Xu ◽  
Wen-Jing Jiang ◽  
...  
Keyword(s):  
Deep Eutectic Solvents ◽  
Acid Sites ◽  
Weak Acid ◽  
Selective Absorption ◽  
Highly Efficient

scholarly journals Effect of pyrolysis temperature on Si release of alkali-enhanced Si-rich biochar and plant response

Biochar ◽  
2021 ◽  
Author(s):  
Meng Wang ◽  
Negar D. Tafti ◽  
Jim J. Wang ◽  
Xudong Wang
Keyword(s):  
Rice Straw ◽  
Rice Husk ◽  
Pyrolysis Temperature ◽  
Weak Acid ◽  
Rice Grain ◽  
Neutral Salt ◽  
Salt Solutions ◽  
Plant Disease Control ◽  
Si Content ◽  
Lower Temperature

AbstractRecent studies have shown that silicon (Si) dissolution from biochar may be influenced by the pyrolysis temperature. In addition, the enhancement of biochar by treatment with alkali has been proposed to produce a Si source that can be used for environmentally friendly plant disease control. In this study, biochars from rice straw and rice husk pretreated with KOH, CaO and K2CO3 and then pyrolyzed at 350, 450 and 550 °C were prepared to evaluate the effects of pyrolysis temperature on Si release and plant uptake from alkali-enhanced Si-rich biochar. Extractable Si and dissolution Si from the prepared biochars were assessed by different short-term chemical methods and long-term (30-day) release in dilute acid and neutral salt solutions, respectively, along with a rice potting experiment in greenhouse. For both rice straw- and husk-derived alkali-enhanced biochars (RS-10KB and HS-10K2B, respectively), increasing the pyrolysis temperature from 350 to 550 °C generally had the highest extractable Si and increased Si content extracted by 5-day sodium carbonate and ammonium nitrate (5dSCAN) designated for fertilizer Si by 61–142%, whereas non-enhanced biochars had more extractable Si at 350 °C. The alkali-enhanced biochars produced at 550 °C pyrolysis temperature also released 82–172% and 27–79% more Si than that of 350 °C produced biochar in unbuffered weak acid and neutral salt solutions, respectively, over 30 days. In addition, alkali-enhanced biochars, especially that derived from rice husk at 550 °C facilitated 6–21% greater Si uptake by rice and 44–101% higher rice grain yields than lower temperature biochars, non-enhanced biochars, or conventional Si fertilizers (wollastonite and silicate calcium slag). Overall, this study demonstrated that 550 °C is more efficient than lower pyrolysis temperature for preparing alkali-enhanced biochar to improve Si release for plant growth.

scholarly journals Reaction of Chalcones with Cellular Thiols. The Effect of the 4-Substitution of Chalcones and Protonation State of the Thiols on the Addition Process. Diastereoselective Thiol Addition

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4332
Author(s):  
Fatemeh Kenari ◽  
Szilárd Molnár ◽  
Pál Perjési
Keyword(s):  
Biological Effects ◽  
Equilibrium Composition ◽  
Deprotonated Form ◽  
Degree Of Ionization ◽  
Thiol Reactivity ◽  
Michael Type Addition ◽  
Ph Conditions ◽  
The Difference ◽  
Initial Reactivity

Several biological effects of chalcones have been reported to be associated with their thiol reactivity. In vivo, the reactions can result in the formation of small-molecule or protein thiol adducts. Both types of reactions can play a role in the biological effects of this class of compounds. Progress of the reaction of 4-methyl- and 4-methoxychalcone with glutathione and N-acetylcysteine was studied by the HPLC-UV-VIS method. The reactions were conducted under three different pH conditions. HPLC-MS measurements confirmed the structure of the formed adducts. The chalcones reacted with both thiols under all incubation conditions. The initial rate and composition of the equilibrium mixtures depended on the ratio of the deprotonated form of the thiols. In the reaction of 4-methoxychalcone with N-acetylcysteine under strongly basic conditions, transformation of the kinetic adduct into the thermodynamically more stable one was observed. Addition of S-protonated N-acetylcysteine onto the polar double bonds of the chalcones showed different degrees of diastereoselectivity. Both chalcones showed a Michael-type addition reaction with the ionized and non-ionized forms of the investigated thiols. The initial reactivity of the chalcones and the equilibrium composition of the incubates showed a positive correlation with the degree of ionization of the thiols. Conversions showed systematic differences under each set of conditions. The observed differences can hint at the difference in reported biological actions of 4-methyl- and 4-methoxy-substituted chalcones.

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