China
Africa
Explore chapters and articles related to this topic
Basic Chemical Principles
Published in John A. Conkling, Christopher J. Mocella, Chemistry of Pyrotechnics, 2019
John A. Conkling, Christopher J. Mocella
Most of the common bases are ionic compounds consisting of a positive metal ion and the negatively charged hydroxide ion, OH−. Examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide, Ca(OH)2. Ammonia (NH3) is a weak base, capable of reacting with H+ to form the ammonium ion, NH4+.
Ionic Equilibria in Aqueous Solutions
Published in Franco Battaglia, Thomas F. George, Understanding Molecules, 2018
Franco Battaglia, Thomas F. George
Wishing to buffer a solution at a alkaline pH, one should prepare it from a weak base (with basicity constant Kb) and one salt of it. All the equations (12.69)–(12.73) hold, provided one replaces in them [H+], pH, and the suffix a with, respectively, [OH−], pOH, and the suffix b. The weak base must be chosen with a pKb value as closest as possible to the pOH value to be buffered.
A review of thermodynamic concepts
Published in Ronald L. Fournier, Basic Transport Phenomena in Biomedical Engineering, 2017
In the previous discussion on the Gibbs-Donnan effect, the aqueous solution contained a strong electrolyte such as NaCl. Recall that a strong electrolyte in water completely dissociates into its constituent ions. Oftentimes, in biological systems, our aqueous solutions will also contain weak electrolytes such as weak acids or weak bases. Weak acids and bases only partially dissociate. An important example of a weak acid is acetic acid (CH3COOH or HOAc), and an example of a weak base is aqueous ammonia or ammonium hydroxide (NH4OH). Weak acids and weak bases, because of their partial dissociation, will affect the concentration of H+ and, as a result, the pH of the solution.
Adsorption of Safranin-O dye by copper oxide nanoparticles synthesized from Punica granatum leaf extract
Published in Environmental Technology, 2022
Taynara Basso Vidovix, Heloise Beatriz Quesada, Rosângela Bergamasco, Marcelo Fernandes Vieira, Angélica Marquetotti Salcedo Vieira
It was verified in the CuO-NP characterization that the adsorbent surface is negatively charged (Figure 2). SO is called a weak base (pKa = 11), and its dissociation is represented according to Equation (3) [29]. Consequently, SO at pH < 11 is predominantly in its protonated form (HB+), while at pH > 11 SO is predominantly in its deprotonated form (B). Therefore, between pHs 4-10, SO is in its protonated form, which implies that electrostatic attraction between adsorbent–adsorbate may occur. However, as there were no major changes in the results over the pH range, this mechanism may not be the main one. Other studies also reported similar behaviours, where small changes in the percentage removal of SO were observed at the same pH range evaluated (4-10), indicating hydrogen bonds and π-interactions as the main mechanisms [1,3,54,57].
Immobilization of maize tassel in polyvinyl alcohol for the removal of phosphoric compounds from surface water near farmland
Published in Cogent Engineering, 2021
Muibat Diekola Yahya, Jennifer Osato Agie, Kehinde Shola Obayomi, Adeola Grace Olugbenga, Eyitayo Amos Afolabi
One (1 g) of the maize tassel was weighed on an electronic weighing balance and put in each of the following solution (15 mL) of NaHCO3 (0.1 M), Na2CO3 (0.05 M) and NaOH (0.1 M) to determine the acidic groups sites present in the maize tassel and 0.1 M HCl to determine basic groups sites. Each of the mixture was kept in a cupboard for three days. The acidic and basic groups present in the maize tassel were ascertained by direct titration process. The acidic groups were computed in view that NaOH neutralizes carboxylic, lactonic and phenolic groups, Na2CO3 neutralizes carboxylic and lactonic groups and that NaHCO3 neutralizes only carboxylic groups. Carboxylic groups were calculated by direct titration with NaHCO3. The variation concerning the groups titrated with Na2CO3 and those titrated with NaHCO3 was inferred to be lactones and the change between the groups titrated with NaOH and those titrated with Na2CO3 was presumed to be phenol. Neutralization points were known using pH indicators of phenolphthalein solution for titration of a strong base and strong acid, and methyl red solution for a weak base with strong acid and pH together. To neutralize basic group sites, remaining HCl in the solution was back titrated with 0.1 M NaOH (Ekpete & Horsfall, 2011). Equation (4) was used to solve for the functional groups present in the maize tassel.
In situ aerosol acidity measurements using a UV–Visible micro-spectrometer and its application to the ambient air
Published in Aerosol Science and Technology, 2020
Myoseon Jang, Shiqi Sun, Ryan Winslow, Sanghee Han, Zechen Yu
The equilibrium constant () of a weak base (pH indicator) is expressed as (Bunnett and Olsen 1966; Hammett and Deyrup 1932): where is the activity and is the molarity activity coefficient. Equation (5) is rewritten as: is a basicity as a form of –log (). The activity coefficient term is defined as excess acidity (X) (Bunnett and Olsen 1966; Perrin 1964),