Dissolution of sodium hydroxide in water

Contents • 1 Properties • 1.1 Physical • 1.2 Chemical • 2 Preparation and Acquisition • 3 Uses • 4 Handling • 4.1 Safety • 4.2 Storage • 4.3 Disposal • 5 References • 5.1 Relevant Sciencemadness threads Properties Physical Sodium hydroxide is an odorless hygroscopic white solid. Due to its hygroscopic nature, sodium hydroxide will readily absorb enough water from the air to dissolve itself; for this reason, samples are hard to weigh accurately in dry form and standardized solutions are often used for more precise chemistry. The dissolution of sodium hydroxide into water is very highly exothermic; lower-quality glassware can even break from thermal stress if this reaction proceeds too quickly. Sodium hydroxide is soluble in water, Chemical Concentrated solutions of sodium hydroxide also have the unique property of being one of the few things that can dissolve glass, and even dilute solutions will do this over long time. Molten sodium hydroxide is much more powerful and will dissolve glass much faster, forming 2 NaOH + SiO 2 → Na 2SiO 3 + H 2O For this reason, sodium hydroxide should be stored only in thick plastic containers. Sodium hydroxide is also unique among basic compounds in that it reacts vigorously with 2 NaOH + 2 Al → 2 NaAlO 2 + H 2 Sodium hydroxide does not attack 2 NaOH + Cl 2 → 2 NaClO + H 2O In a process known as saponification, which is used in soapmaking, sodium hydroxide can hydrolyze organic esters such as those found in naturally occurring plant or anima...

Chemical changes are characterized by the formation of new substances and the making and breaking of strong chemical bonds. When caustic soda is dissolved in water, strong ionic bonds between sodium and hydroxide ions are disrupted, are broken, and strong bonds are formed between the sodium ions and the water molecules. The balance of bonds formed versus bonds broken lies in favour of bond formation in that the dissolution is quite exothermic: #NaOH(s) + "excess "H_2O(l)rarr Na^(+)(aq) + HO^(-)(aq) # We write, #Na^(+)(aq)#, to represent the aquated ion, #[Na(OH_2)_6]^+#, and likewise the hydroxide ion, represented as #HO^-#, is probably a cluster of 3 or 4 water molecules, LESS a proton, to give #[H_5O_3]^-#. Given this chemical reality, in which bonds ARE BROKEN, and BONDS ARE FORMED along with NEW SUBSTANCES, the dissolution is probably best regarded as an example of chemical change. Now this is an undergraduate treatment, not an A level treatment. If you are in high school, canvas your teacher's opinion, and adopt it.

When you write down the net ionic equation, you have to consider that the educt and the products are in different phases, a solid and a liquid phase. Undissolved $\ce$$ Thanks for contributing an answer to Chemistry Stack Exchange! • Please be sure to answer the question. Provide details and share your research! But avoid … • Asking for help, clarification, or responding to other answers. • Making statements based on opinion; back them up with references or personal experience. Use MathJax to format equations. To learn more, see our

\begin The dissolution of sodium hydroxide in water is an exothermic process, and so, according to Le Chatelier’s principle, cooling the container should shift the reaction to the right. Shouldn’t this mean that cooling the container will increase the solubility? According to a solubility chart for sodium hydroxide, heating the container will increase the solubility; why is this the case? The question to the Newton - Ask a Scientist program by Danna C Griffiths (to be found via What I understood from the explanation on that site: Solubility is defined as the concentration of the solute in a saturated solution. So when considering the increase in solubility with temperature, you have to check the enthalpy of solution of $\ce$ to dissolve). So according to Le Chatelier’s Principle, although the dissolution process is overall exothermic, since solubility is determined only at the saturation point, the solubility increases with increase in temperature. This reaction has a positive change of entropy (ΔS > 0). Hence, from the equation ΔG = ΔH - TΔS, we find that its Gibbs energy will decrease with an increase of the temperature. As a results, the solubility of NaOH increases when we increase the temperature (heating the container), since we have ΔG = -RTlnK.

1 Essential Ideas • Introduction • 1.1 Chemistry in Context • 1.2 Phases and Classification of Matter • 1.3 Physical and Chemical Properties • 1.4 Measurements • 1.5 Measurement Uncertainty, Accuracy, and Precision • 1.6 Mathematical Treatment of Measurement Results • Key Terms • Key Equations • Summary • Exercises • 2 Atoms, Molecules, and Ions • Introduction • 2.1 Early Ideas in Atomic Theory • 2.2 Evolution of Atomic Theory • 2.3 Atomic Structure and Symbolism • 2.4 Chemical Formulas • 2.5 The Periodic Table • 2.6 Ionic and Molecular Compounds • 2.7 Chemical Nomenclature • Key Terms • Key Equations • Summary • Exercises • 6 Electronic Structure and Periodic Properties of Elements • Introduction • 6.1 Electromagnetic Energy • 6.2 The Bohr Model • 6.3 Development of Quantum Theory • 6.4 Electronic Structure of Atoms (Electron Configurations) • 6.5 Periodic Variations in Element Properties • Key Terms • Key Equations • Summary • Exercises • 7 Chemical Bonding and Molecular Geometry • Introduction • 7.1 Ionic Bonding • 7.2 Covalent Bonding • 7.3 Lewis Symbols and Structures • 7.4 Formal Charges and Resonance • 7.5 Strengths of Ionic and Covalent Bonds • 7.6 Molecular Structure and Polarity • Key Terms • Key Equations • Summary • Exercises • 9 Gases • Introduction • 9.1 Gas Pressure • 9.2 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law • 9.3 Stoichiometry of Gaseous Substances, Mixtures, and Reactions • 9.4 Effusion and Diffusion of Gases • 9.5 The Kine...