Reaction Of Naoh And Hcl

Chem 1252, Full general Chemistry I Lab

Johnson

Acid-Base Titrations

Introduction

Titration is a convenient quantitative method for accurately determining unknown concentrations of

solutions. A necessary requirement for its apply is that a standard solution (a solution of known

concentration) reacts chemically with the solution whose concentration is existence adamant. The standard

solution is added to a solution of unknown concentration until all of the unknown solution has reacted.

From the known quantity and molarity (or normality) of the standard solution and the measured book of

unknown solution used, the unknown concentration tin can be calculated. For example, standard base solution

(NaOH) is added from a burette to an accurately known volume of the acrid solution (HCl).

HCl(aq ) + NaOH( aq ) ------------> H ii O( fifty) + NaCl( aq)(1)

This reaction (neutralization) can be written as a Internet IONIC equation as follows:

H+ (aq ) + OH- (aq ) ----------> H two O( l) (2)

When sufficient NaOH has been added to react with all of the acid, the titration is consummate -- the

equivalence signal has been reached. Most acrid-base solutions are colorless and determining when ane

reactant has been totally consumed is difficult by unproblematic observations. To allow usa to visually decide

this point, we use compounds called acrid-base indicators to tell the states when a reaction is complete. Dyes

(usually weak organic acids) whose colors depend upon pH are often used to signal the completion of acid-

base reactions. Indicators must be carefully chosen based on the pH of the equivalence betoken of the

titration. In this experiment, a strong base of operations (NaOH) is being added to a strong acrid (HCl). An indicator that

changes color when the pH becomes greater than 7 (more base is added than necessary) is used. Titrations

involving a strong acid and a strong base normally employ phenolphthalein as an indicator.

Phenolphthalein changes from colorless to cherry-red at a pH of ≈ 8-10.

At the point when the indicator changes color (also called the endpoint) and from the internet ionic equation

given higher up, we can see that the moles of H+ equal the moles of OH- . From the molecular equation (Eq 1),

we too see that the number of moles of HCl equals the number of moles of NaOH at the endpoint.

moles H + = moles OH -

moles acid = moles base of operations

M aV a = Thousand bV b

Grooming of a standard NaOH solution is not a uncomplicated chore. Solid NaOH is hygroscopic - it readily

absorbs water from the atmosphere. Thus, solutions of exact NaOH concentrations cannot be prepared past

weighing out the calculated amount of NaOH and dissolving information technology in a given quantity of water. To set

standard NaOH solutions direct, anhydrous NaOH must be weighed in a water-free surround (under

normal conditions, you tin can observe the mass of NaOH increase as yous weigh it on an analytical balance).

Another trouble in the preparation of standard NaOH solutions is the need to remove dissolved CO2 from

the h2o used. NaOH reacts with COii to produce Na 2CO 3.

2NaOH( aq) + CO 2(aq ) ---------> Na 2CO iii(aq ) + H 2O( l) (3)

NET IONIC REACTION:

2OH - (aq) + CO 2(aq )---------> CO 2-

3(aq ) + H 2O( l) (four)

Reaction Of Naoh And Hcl,

Source: https://www.studocu.com/en-us/document/augusta-university/organic-chemistry-ii/hcl-naoh-lab-lab-report/18009158

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