Why is Al(OH)3 insoluble in water, but soluble in acid and base solutions?
Aluminum hydroxide is amphoteric -- it reacts with both acids and bases. Like any conventional base, the OH radical in Al(OH)3 neutralizes H+ to make water and an aluminum salt. Al(OH)3 solid will also react with excess OH- to dissolve and form the complex ion [Al(OH)4]-.
Why would a compound that is insoluble in water soluble in 2.5 M NaOh solution?
A number of oxides and hydroxides that are highly insoluble in water at pH = 7 dissolve in conc OH- to give cmplx ions of the type [M(OH)4]n-. They are said to be amphoteric [1]. Two of the best known examples are: Al(OH)3 + NaOH → Na[Al(OH)4] ZnO + H2O + 2OH- → [Zn(OH)4]2- More examples are listed in ref [1]. Copper is not listed but it also forms the soluble [Cu(OH)4]2- in conc OH-. Reasons for solubility: the Na[Al(OH)4] (for example) has a lower lattice energy than Al(OH)3 because the [Al(OH)4]- is larger; favorable ΔHform, Kf for Zn(OH)42- = 4.6 x 10^17, and third, presumably, is that the [Al(OH)4]- has a larger solvation energy than OH-.
Is Na2Co3 soluble or insoluble?
Yes, sodium carbonate is soluble (although only slighty) in water all salts are soluble except for a few notable exceptions...Here is some lecture notes for my chemistry class that explains (look at bottom): Table 4.1 Simple Rules for Solubility of Salts in Water (p. 105) 1. Most nitrate (NO3-) salts are soluble. 2. Most salts of Na+, K+, and NH4+ are soluble. 3. Most chloride salts are soluble. Notable exceptions are AgCl, PbCl2 , and Hg2 Cl2 . 4. Most sulfate salts are soluble. Notable exceptions are BaSO4 , PbSO4 , and CaSO4 . 5. Most hydroxide salts are only slightly soluble. The important soluble hydroxides are NaOH, KOH, and Ca(OH)2 (marginally soluble). 6. Most sulfide (S2-), carbonate (CO32-), and phosphate (PO43-) salts are only slightly soluble.
Is CaCO3 soluble or insoluble?
As Malcolm pointed out, calcium carbonate is indeed only very slightly soluble in neutral water (pH7). However, that solubility increases significantly in rain water (pH~5) due to the CO2 on the air. This 'solubility' is actually a chemical reaction of the acid-base type that Kumaraswami mentioned;-CaCO3 + CO2 +H2O --->Ca+2 + 2HCO3- (Where CO2 + H2O produces carbonic acid, H2CO3)This reaction speeds up the dissolution of limestone greatly. However it still takes a long time to form a cave, even at this faster rate.
Why is benzoic acid more soluble in an aqueous alkaline solution than neutral or acid solution?
Benzoic acid is first and foremost a weak acid and thus dissociates partially in water:C6H5COOH + H2O <---> C6H5COO- + H3O+From this equation and the structure of benzoic acid, you can tell three things:In a neutral solution, benzoic acid is slightly soluble in water. It is nearly insoluble in cold water but highly soluble in hot water. This is because even though water can form hydrogen bonds with the carboxylate functional group, the bulk of the benzoic acid is still the large benzene ring, which can only form Van der Waals forces of attraction with water (significantly weaker than hydrogen bonding). Also, even though benzoic acid can dissociate in water, as it is a weak acid, it can only dissociate partially, which is insufficient to dissolve benzoic acid. Thus, benzoic acid is insoluble in cold water.However, as temperature increases, more energy is present to overcome the hydrogen bonding between water molecules to form weaker Van der Waals forces of attraction between benzoic acid and water. Also, more energy is present to drive the dissociation of benzoic acid forward, as it is endothermic, thus benzoic acid becomes more soluble in hot water.In alkaline medium, benzoic acid becomes soluble. The abundant OH- ions will react fully with benzoic acid in acid-base reaction to form water and benzoate ion, which now is soluble in water due to strong ion-dipole forces of attraction.In acidic medium, benzoic acid becomes insoluble. The increase in concentration of H+ ions will shift the position of equilibrium of dissociation of benzoic acid to the left, causing benzoic acid to be hardly soluble in acidic medium.
What type of compounds are soluble in water? Why?
Compounds that have polarity.In water, hydrogens and the oxygen share electrons. Both try to attract the electrons, the power of the attraction is called electronegativity.The electron-pair goes a bit closer to oxygen. So a partial negativity is created there. And of course, on the other side, in hydrogens, positivity occurs.So the compounds which can be splitted into these two sides, will attract the opposite sides respectively. That's why water, sugar, alcohol, though being covalent compounds, still get dissolved in water. And ionic compounds get dissolved easily as they are born with positive and negative ions.
Why are hydrocarbons insoluble in water?
Hydrocarbons are organic compounds containing the element Hydrogen and Carbon ONLY. If it contains Oxygen or any other elements, It is NOT a Hydrocarbon.That means, Hydrocarbons includes the Homologous series such as Alkanes, Alkenes and Alkynes and its isomers. Some Polymers are also included.To answer your question, my answer would be “No, they are not soluble in water”Hydrocarbons are organic compounds with covalent bonds. They have a simple molecular structure and one property of having a simple molecular structure is that it's not soluble in water but only soluble in organic solvent. In fact, Hydrocarbons are sometimes used as a solvent for other organic compounds.But why does having a simple molecular structure makes it immiscible in water? Let us take Alkanes, for example, it has weak inter-molecular forces (weak induced dipole forces) and is held by covalent bonds. The reason why it is not able to dissolve in water and form a suspension in water is due to Polarity.Water is polar, which means one side of the molecule is more electronegative than the other. However, an Alkane (Hydrocarbon) which only contains 2 elements, is Non-Polar. Polar substance tends to dissolve in a Polar solvent and hence, Alkanes being Non-Polar, will not dissolve in Polar Solvent.Oils are also hydrocarbons. Have you ever mix oil and water together only to realise that it forms a suspension?The answer is Polarity and you can also call it the Hydrophobic effect.Hydrophobic effect - WikipediaWith what I’ve known so far, I do not know of any hydrocarbon that are soluble in water at the moment, maybe you could argue that there are some exceptions just like how Mercury being a metal have such low melting point, but if there is please let me know.Have a Nice day ,Hope I’ve answered your question , Please correct me if I’mwrong
Does the solute dissolve faster if there is more solvent?
Imagine dropping a tablespoonful of salt/sugar into a full glass of water & the same amount into a glass having only a teaspoon of water. Stir (or don’t) both solutions. What might you expect to see? *If the volume of solvent is sufficient to absorb all the molecules of your solute, then both should vanish into solution, but, because there aren’t so many water molecules in a teaspoon of water the solute will struggle to fit it’s atoms into the gaps between them. Stirring (or heating the solvent) aids that process by bringing new water molecules into contact more quickly with the salt/sugar. Now imagine if you have the glass of water into which a tablespoon of salt/sugar vanished within a few seconds, and alongside that glass you now have… a bucket of water. What will happen when you drop your solute into each container of water? Will they dissolve faster if they have more water to dissolve in? All the while the crystals are falling under gravity (provided their Density is greater than that of water) their molecules must be reacting or intermingling with the water molecules (dissolving) so it seems intuitive to conclude that yes, if there is more rather than less solvent available - even if you do nothing else to facilitate the process - the solute will dissolve faster.
Why does NH3 gas have the highest solubility in water compared to others?
Polar compound dissolve polar molecule.The polarity of NH3 molecule is due to the hydrogen bond between water and ammonia.Molecules that can hydrogen bond with water have higher solubility in water. Molecule which are capable of hydrogen bond, have hydrogen atom which are covalently bonded to highly electronegative elements( O, F, N). The presence of hydrogen bbonding between molecule of substance indicate that the molecule polar.