Why does salt crystals dissolve in the water?

Question

why does salt crystals dissolve in water?

Answer 1

Natalee's answer is very good. I only wish to add a few things to it. Depending on the level of biology or chemistry course, these other factors might be part of your answer.

The dissolution of NaCl in liquid water is what we call a spontaneous process. It occurs without the addition of any more energy. Spontaneous processes occur because they lower the free energy of a system. In general, breaking bonds takes energy and making bonds releases that energy. Free energy can take the form of bonds (enthalpy, S) or degree of disorder (entropy, H). The most well known equation for free energy changes is:

ΔG = ΔH – TΔS

(ΔG is the change in free energy. If ΔG < 0, the process is spontaneous. ΔH is the change in enthalpy, T is the absolute temperature, and ΔS is the change in entropy.)

When NaCl dissolves, the Na+:Cl- ionic bonds are lost. Some of this increased free bond energy is offset by the formation of new bonds, the transient interactions between the polar water molecules and the dissolved ions. However, most of the increased free bond energy is made up for by the increased entropy. The number of ways you can make a salt crystal is very small. NaCl crystals are highly organized, with very low entropy. The number of states the same Na+ and Cl- ions can occupy when surrounded by water molecules is relatively much, much greater. Thus the entropy of the solution is much greater. There are many ways to organize the Na+ and Cl- ions within a see of H₂0 where the Na+ and Cl- are not adjacent to each other. This is a more entropic situation.

The increase in entropy is a decrease in free energy. This is the main driver in the dissolution of water.

Another consideration is the kinetics of the dissolution. While the change in free energy tells you which direction the process goes (towards dissolution), it doesn’t tell you how fast it occurs. It turns out that the energy present at room temperature, in liquid water, is strong enough to break those Na+:Cl- ionic bonds, so the process happens at a fairly reasonable rate (minutes, not years).

Again, all of this might be too advanced, depending on the biology class. Use your judgment.

Answer 2

Good question Samantha. Let’s first take a look at salt and water at the molecular level. Salt, also written out as NaCl (Sodium Chloride), is made up of positive sodium ions (Na+) along with negative chloride ions (Cl-). Because we have a positive and negative, the two are attracted to each other forming an ionic bond, which results in NaCl. When many sodium and chloride ions attract to one another, they form a salt crystal. When this formation occurs, you get a sodium ion that is surrounded by 6 chloride ions and a chloride ion surrounded by 6 sodium ions to form a cube.

Now let’s look at water (H20) on the molecular level. A water molecule is made up of two hydrogen atoms bonded to one oxygen atom. The oxygen molecule has a great attraction for the electrons that are found on the hydrogen. As a result, the electrons spend most of their time near the oxygen than the hydrogens. This then makes a slight negative charge around the area of the oxygen and slight positive charge around the hydrogen.

So, when salt crystals are placed in water, the positive end of the water molecule attracts the negatively charged chloride ions and the negative ends of the water molecules attract the positive sodium ions. As a result, the salt will dissolve once the attraction between the water and the ions overcomes the attraction the ions have for one another. Once dissolved, the positive sodium ions and negative chloride ions will associate with the oppositely charged polar ends of many water molecules.

Hope this helps!

Answer 3

I think these are both good answers. However, I wish to point out that the term "salt" may refer to any of a tremendous number of ionic compounds. The term "ionic" refers to the property that each of these compounds will dissolve in water, splitting into the "ions" that carry the positive (cation) or negative (anion) charge.

Answer 4

ionic compounds completely disassociate in water because water is polar. The partial negative charge (or more electronegative aspect of water) of the O interacts with the positive end of NaCl (Na+) and the partially positive aspect of water (the Hydrogens) interacts with the Cl in aqueous solution of water. They completely disassociate in water and become ions, Na+ and Cl-.

A reaction would look something like:

NaCl(s) + H2O(l)----> Na+(aq) + Cl-(aq)

Answer 5

All the answer are good but I will like to add a few point in term of electrolysis and correct me if I am wrong . electrolysis occur when a compound split into several ion when electricity is applied to it . it occur in both molten state I.e raw element applied at high current to dissolve in to two ion. And also in solution when water is added to the current and heat is applied to enable the splitting process occur. And there are two rod in electrolytic cell the cathode been the negative. And the anode being the positive and for this to occur three rule is applied 1 nature of electrode

2 according to concentration

3 preferential discharge according to electro negatively and electro positively charge

Answer 6

generally on the basis of chemistry i would say this

while some salts undergo hydrolysis because of they have vacant d orbitals and can form coordination compounds with water most salts tend to be the second law of thermodynamics where

deltaG=deltaS - TdeltaH

the explanation of which has been offered above

goodday :)

Answer 7

Because for instance, sodium chloride, NaCl, is bonded ionically. Water is a dipole, which means it has a slightly positive and slightly negative charge. Either side is compatible with binding to sodium or chloride ions. Salt in a solution is overtaken by water molecules, and separates the salt into two components, a sodium ion and a chloride ion, which are now covered by water.

Answer 8

Salt water, which is naturally found in the oceans and lakes in the world, is used for a variety of purposes today, both in science and in everyday life. Salt dissolution in water is an extremely ordinary happening that many people have not even thought about it.

Yet this insignificant phenomenon is a complex process that can be explained by the physical laws of our universe and the fundamental principles of the science of chemistry.

In this article, we will examine salt water, and try to answer questions such as "Why does salt dissolve in water?" and "How to separate salt from water?". To do so, we need to refresh our knowledge of chemistry.

Why Does Salt Dissolve in Water?

It is important to understand the principles of chemical bonds of elements to address this query. There are four types of chemical bonds: ionic bonds, covalent bonds, hydrogen bonds, and Van der Waals interactions. We need to understand only the ionic and covalent bonds today.

Ionic Bonds

The ionic bond is a kind of chemical bond between opposite-charged ions, which occurs due to electrostatic attraction. A positively charged ion forms a bond with a negatively charged ion by transferring electrons from one atom to another.

The formation of an ionic bond is based on electron exchange. The atom that loses electrons is a cation (positively charged), while the atom that wins electrons is an anion (negatively charged). An intense electrostatic attractional force occurs between the anion and the cation during the interaction.

The ionic bond allows the two ions to stand together. This kind of bond can never form between neutral particles. Cations and anions must exist for this event. The number of electrons received and given is equal to each other in the exchange of electrons that occurs when an ionic bond is formed.

Covalent Bonds

Covalent bonds are the most common and strongest form of chemical bonds found in living organisms. If two elements share one or more electrons, this is known as a covalent bond.

A single covalent bond is formed when two nonmetallic atoms share a pair of electrons, a binary covalent bond is formed when two pairs of electrons are shared, and a triple covalent bond is formed when three pairs of electrons are shared.

Since the shared electrons spend more time between the two cores, they build a (-) loaded area. This area forms a bond by applying an attraction force to both cores.

Salt Dissolution in Water

The NaCl compound (the main compound of table salt) is an ionically bound, crystalline compound. Water molecules dissolve the Na and Cl atoms, which are bound in crystal form before being dissolved. As a result, water is a solvent.

As the crystals of NaCl molecules dissolve in water (H2O), hydrogen (H) ions of water molecules surround (-) charged chlorine (Cl) ions of salt. Likewise, (-) charged oxygen (O) ions, (-) surround (+) charged sodium (Na) ions.  Electrostatic attraction is the force that causes this event.

After this process, water molecules get between sodium and chlorine ions and separate them. Thus the salt is dissolved in water. The isolated ions are spread evenly in the solvent to form a homogeneous mixture.

This process continues until the salt is completely dissolved. If the amount of salt added to the water is too much, some of the salt will not dissolve and will sink to the bottom. Salt dissolves but does not melt in water. The melting event occurs in a completely different wa

Answer 9

Ionic compounds completely disassociate in water because water is polar. The partial negative charge (or more electronegative aspect of water) of the O interacts with the positive end of NaCl (Na+) and the partially positive aspect of water (the Hydrogens) interacts with the Cl in aqueous solution of water. They completely disassociate in water and become ions, Na+ and Cl-.

A reaction would look something like:

NaCl(s) + H2O(l)----> Na+(aq) + Cl-(aq)

OR

NaCl + H2O ---> HCL + NaOH, yielding a strong acid and strong base, Usually in aqueous solutions or when NaCl or similar salts which acts as buffer go to reaction this is how it goes but it is usually more favorable to go the other way in which, a strong acid is combined with a strong base to produce a salt like NaCl and H2O.