A Short Note On Sodium Hydroxide As An Indicator Of Acid Base Reactions

1370 Words Mar 30th, 2015 null Page
Phenolphthalein is often used as an indicator in acid base reactions. The reaction used in this lab is:
C_20 H_14 O_(4 (aq))+46 NaOH_((aq))→46 Na_( (aq))^++20 H_2 CO_(2 (aq))+10 H_2 O_((l)).
Phenolphthalein and sodium hydroxide react to form carbonous acid, water, and Na+ ions. This reaction is a neutralization reaction, where phenolphthalein, a weak acid, reacts with a strong base, sodium hydroxide. When phenolphthalein is put into a basic solution, it turns pink. The phenolphthalein ion is pink, and when a base and phenolphthalein are combined, more H+ ions are removed and the equilibrium moves to the right. At the endpoint of a reaction, all of the H+ ions have reacted and been neutralized, so the phenolphthalein ionizes resulting in a pink solution. The phenolphthalein used in this lab was the deprotonated phenolate form, In2−, because the solution turned pink.

Report:
A: The reaction between potassium hydrogen phthalate and sodium hydroxide is a neutralization reaction. The equation is KHP(aq) + NaOH(aq)  KNaP(aq) + H2O(l). Standards are often used in chemistry. Standards have a known concentration of a substance and can be used to determine other information. These materials can be used as a reference to compare to other substances or to determine unknown concentrations. There are two types of standards: primary and secondary. Primary standards are often used in titrations. Primary standards are very pure and stable, and normally have a high molecular weight. They…

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