Acid Base Titration?

Question

What is an acid base titration?

I am not sure, I have a little understand but this is what i know

* you mix in two substances
* then one substance takes over another substance
*then there are some left over something like limited reactant
*finally, neutralization, i don't get that part

please, the book is so confusing...is there a very simple way to explain this to me?

THanks

Answer 1

Hello Miroku -



Let's see if we can be of help. You are simply trying to balance the acidic ions (H^+) with alkaline ions (OH^-).

This comes from the equation:



2 [H^+] + [O^-2] ---> HOH



HOH is water.



All titrations follow this method, but for the specific ion you are trying to titrate for. You know that on the left hand side are the reactants and on the right hand side are the products.

What is contained in the buret is called the "titrant." This can either be an acid or a base or it can be another compound, such as in an oxio-reductase titration, whatever you are trying to do to determine the specific quantity of ions. In the reaction I have given you, you are determining the total amount of hydrogen ion or hydroxyl ions, using one or the other KNOWN concentration as the titrant. The unknown is your sample.



By knowing the concentration and kind of titrant, you have solved two of the four unknowns in getting an answer. By using a specific VOLUME of the sample, you have solved for the third of four unknowns. This leaves one unknown left, which is the concentration of the sample. I will use the following equation to demonstrate this, in terms of what is called NORMALITY (or equivalents). You can also use this equation to determine MOLARITY.



N1V1 = N2V2



N1 is the normality or molarity of the titrant

V1 is the volume of titrant to complete the reaction and arrive at the endpoint.

V2 is the volume of the sample

N2 is the normality or molarity of the unknown sample



The above equation is solved by:



N2 = N1V1/V2



This gives you the concentration of the unknown sample's ion you are determining by titration.



A slight excess, usually a drop or two, is used, to ensure that the reaction has been completed so that all the reactants are now converted totally to products. A GOOD analyst however, is one who learns how to just complete the titration without having to use an excess. The drop or two extra constitutes a potential error in the estimation of the unknown concentration. So learning the exact color of the endpoint is important. Sometimes, the color change is very hard to discern. A difficult one I am familiar with is determining the color change of titrating a Calcium Chloride solution with Calcium Disodium EDTA using erichrome T black as the indicator. The color change goes from a bluish purple color to a steel greyish purple and the endpoint is very difficult to see with the eyes. Another one is determining the amount of chloride ions by using silver nitrate. This one requires you to see very slight changes in a canary yellow color. This one is very easy to overshoot the endpoint.



I hope this helps you a little bit more in understanding what you are doing.

Answer 2

Think about what you're adding together. For the sake of simplicity, let's define an acid as anything that gives a proton to a solution, and a base as anything that gives an OH to a solution. Acids and bases are termed "strong" or "weak" based on their ability to give away their H+ or OH- groups. A strong acid gives away its H+ as soon as it comes into contact with water, and cannot take it back. A strong base steals and H+ from the water, and makes an OH- in solution, but is really bad about returning the OH-. A weak acid gives H+, but it can also take it back in a reversible reaction. A weak base takes an H+ to make OH-, but can also give backs its H+ in a reversible reaction. Every weak acid has a twin that is a weak base, just missing its proton. So, if you put strong and strong, they react violently. If you put in an equal number of moles of each, the moles of H+ and the moles of OH- will get together and make a mole of water. So, every acid molecule and every base molecule have a partner, the pH will be neutral (7) 'cause they've cancled everything else out. With a strong/weak titration, things go a little bit differently. The two are essentially the same, though, in principle, and work by the same mechanism. Let's look at an strong base/weak acid titration, 'cause they're really common. As you add the strong base to the mixture, it pulls H+ away from the acid, and makes the conjugate base. But, that weak base pulls H+ from water, and makes OH-! So, when you have neutralized all the acid in the mixture, your final pH will actually be a little bit higher than 7 because of the equilibrium. When you have a weak acid and a strong base, the final pH is lower than 7. When you do a weak/strong titration, you can find the pKA, or the pH at which the concentration of acid/base conjugate pair twins are equal. This happens at the pH which corresponds to exactly half the volume of acid added. If you're in a lab working with a burette and color indicator, the point can sometimes be hard to find. Colorimetric titration is an art-form. If you have a pH meter, make a plot of pH vs. volume added. Then, take the second derivative of the line. The second derivative of this plot is 0 at the equilivance point.

Answer 3

the acid base titration is simply a reaction of neutralization,where an acid react with a base to form a salt and water.for example:we have a quantity of HCl.now we should add NaOH until the the pH is 7(neutral).we take note the quantities(volume) of HCl and NaOH and their concentration.this is the titration.

in this process you should know this formula:

N(a)*V(a) = N(b)*V(b)

N(a) --->nomal concentration of acid

V(a)--->volume of acid

the others are for the base.

bye.

Answer 4

HCl + NaOH -> NaCl + H2O



There is 100ml of 1 mole HCl in the flask, then you titrate with 2 mole NaOH and it needs 50 ml of 2 mole NaOH for newtralization. (Indicator -(e.g.phenolphthalein) has to be added). Once it neutralize (not acid and not base), the indicator changed its colour