Introduction to Indicators

 Hello fam! Welcome back from the short break. I believe that we are all enjoying the summer holidays. We will now continue from a new topic after we discussed about salts last week.


Today, we want to look at the concept of indicators. We need to know that an indicator is a substance that changes color in the presence of an acid or a base. 


The idea of the color change is the first thing that you have to bear in mind about the indicators. Many of us have at one time or another titrated an acid against a base or vice versa. 


The point at which the acid and base have completely reacted in accordance with the stoichiometry of the reaction equation is called the equivalence point.


Let me give you a typical example; Look at the reaction;

2NaOH(aq) + H2SO4(aq) -- Na2SO4(aq) + 2H2O(l)

This reaction would be complete when two moles of sodium hydroxide react with exactly one mole of sulfuric acid. In other words, the amount of titrant added is just enough to neutralize the analyte solution.


How do I know when the amount of titrant added is just enough to neutralize the analyte solution? I have to depend on some kind of reagent  that would visually indicate this point.


Any reagent that can visually indicate the point at which the amount of titrant added is just enough to neutralize the analyte solution is called an indicator.


The indicator solution has a different color in acidic, basic and neutral solutions. Hence, an indicator solution is added in drops to an acid or base analyte solution before the titrant is added. The point at which the color of the solution changes during titration is the equivalence point of the solution.


In everyday experiments in the laboratory, we use the endpoint to determine the amount of substance present in an analyte during volumetric analysis. The end point and the equivalence point are not exactly the same. However, we approximate the both to be equal for convenience sake.


The equivalence point is accurately determined from a titration curve and we shall look at that in due course. How exactly does an indicator work? Join us tomorrow to know more!


Hope you enjoyed our lesson today?

Follow  our page  and share!

Do you have assignments, term papers, projects and difficult homework questions? Contact us for help now! We also offer home and remote tutoring services to students at all levels in science subjects.








Comments

Post a Comment

Popular posts from this blog

Water of Crystallization

Image
 Hello fam! Today we would be looking at the water of crystallization of a salt. It is common to refer to some salts as hydrates. A hydrate is a salt that has its water of crystallization attached to its structure. The term water of crystallization refers to the number of water molecules that combine chemically, in definite molecular proportion with a salt to form a crystalline structure. The number of water molecules attached to the crystal lattice of the salt is usually written alongside the chemical formula of the salt by placing a dot in between the usual formula of the salt and the number of molecules of water attached to the salt lattice. Examples of salts having water of crystallization are; • Na2CO3.10H2O – Sodium carbonate decahydrate • CuSO4.5H2O  - Copper sulfate pentahydrate • CaSO4.2H2O – Calcium sulfate dihydrate  It is important to note that the presence or absence of the water of crystallization affects the properties of the salt. For instance, CuSO4.5H2O is blue in col
Read more

Introduction to complex salts

Image
 Hello fam! Welcome to today’s lesson. We would focus our study today on trying to understand what we mean by a complex salt. I advise that you look at the lessons on June 18 and July 6, 2023 found on the page timeline for a detailed explanation of the idea of the coordinate bond. I will try to give a little introduction here but looking at the lessons I quoted above are indispensable to making the most out of this lesson.  A coordinate bond is formed when ONLY ONE of the bonding species supply the electron pair that is shared in the covalent bond. In other words, a coordinate bond must involve a  Lewis acid (electron pair acceptor) and a Lewis base, (electron pair donor). Let us look at a typical example. Consider the formation of [Cu(NH3)4]Cl2. Remember that the ground state electron configuration of the copper II ion is written as; [Ar]3d9 4s0.  This implies that we have empty 4s and 4p orbitals that can participate in dsp2 hybridization (forming a square planar complex) along with
Read more

Preparation of Salts

Image
 Today, our focus would be on the preparation of salts. We are concerned about how we can make salts. I want to remind you again that a salt is made when hydrogen ion in an acid is replaced by another cation. Let us now consider some of ways by which salts can be made; 1) Reaction of a dilute acid and metal; A salt can be formed when a single replacement reaction occurs between a dilute acid and a metal. The metal used here must be above hydrogen in the activity series. For example; Zn(s) + 2HCl(aq) --> ZnCl2(aq) + H2(g) This kind of reaction is most times given as one of the chemical properties of acids. 2) Neutralization reaction: As I have explained previously, a neutralization reaction occurs between an acid and a base to form a salt and water only. This is one of the most important ways by which soluble salts are formed. For example; KOH(aq) + HCl(aq) -> KCl(aq) + H2O(l) H2SO4(aq) + CuO(s) -> CuSO4(aq) + H2O(l) 3) Dilute acid and carbonate: One of the chemical properties
Read more