hey it's professor Dave. let's talk about solutions
a homogeneous mixture that's in one phase is called a solution
think of something like table salt in water. if we are talking about a liquid
solution, the thing that gets dissolved is called the solute. in this case that's
the salt and the thing doing the dissolving is called the solvent, here
that's the water. solutions tend to retain the properties of the solvent
since solvent particles are typically much more abundant than the solute. we
can say that a solute is either soluble or insoluble in a particular
solvent depending on whether it will dissolve in that solvent. something will
dissolve if in doing so it will make favorable intermolecular contacts with
solvent particles. in the case of salt it will dissolve and dissociate so that the
sodium ions and chloride ions can make ion-dipole interactions with water
molecules. a nonpolar covalent compound will not dissolve in water because
without a dipole it can't make any dipole-dipole interactions with polar
water molecules. that's where we get the saying: like dissolves like. salt water is a
strong electrolyte because the formally charged ions in solution can conduct
electricity. weak electrolytes only partially ionize in solution so they
conduct electricity weakly. we can use molecular equations to describe
substances that transform in solution and it will be useful to use subscripts
after each compound to show its phase. solid liquid and gas and we use
the word aqueous to describe ions that dissociate in solution. this is important
because sometimes ions come together to form a new compound which may be
insoluble in that solvent. in such a case we will denote that it is in the solid
phase as it will crash out of solution as a precipitate. we can write molecular
equations to describe solution chemistry
but we can also use net ionic equations. this summarizes the key transformation
by eliminating spectator ions, the ones that just sit in solution and don't do
chemistry. to do this we start by writing the complete ionic equation. this
involves splitting the ionic compounds into their respective ions, just
remember the common charges of the ions to include the correct formal charges
subscripts in the molecular equation become coefficients in the complete
ionic equation since all the components are dissociating. anything that's
present on both sides we can cancel out like an algebra problem. these are the
substances that don't do any chemistry. what's left are the two ions that come
together to form a solid precipitate which is a chemical change. this is the
net ionic equation. in addition sometimes we categorize these kinds of reactions
as being either synthesis where two things become one
decomposition where one thing becomes two. single displacement where one component
swaps out, or double displacement where two components switch places. this is
just good vocabulary to know let's check comprehension
thanks for watching guys subscribe to my channel for more tutorials and as always
feel free to email me