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When a strong acid is titrated with a strong base using phenolphthalein, the color changes suddenly at the end point. The color

larisa86 [58]

Answer:

Keto - enol tautomerism

Explanation:

Phenolphthalein is an organic molecule (formula: C20H14O4), which is used in to determine the final volume in an acid-base titration, this is, as the molecule changes from one to another color, depending on the Ph of the solution (in acids solution, the molecule remains colorless, while in basics solutions it remains pink) :

The molecule of phenolphthalein is a week acid, which losses a proton (H+) when it´s in solution: the undissociated molecule is colorless, while the correspondent anion (without a H+) is pink. This may be simplified with the following reaction:

H₃In⁺ ⇄ H₂In (colorless) ⇄ In⁻² (pink) ⇄ In(OH) ⁻³

- When adding a base (for example, NaOH) to phenolphthalein (initially, a colorless solution), molecule losses one H⁺ and we obtain In⁻², which is pink

- When adding an acid, the original structured is recovered, so color turns from pink to colorless

This change color is not only explained with adding an acid or a base, but also with phenolphthalein structure, that leads to a keto-enol tautomerism: as molecule has 2 hydroxyl groups (- OH) and 1 carbonyl group (C = O), compounds with this structure have an equilibrium between both groups:

R1 = C H– OH ⇄ R1 – C = O

With this change, phenolphthalein structure changes and hence, color solution changes as well

4 0

3 years ago

Periodic Trends<br>PLEASE HELP ME! I WILL GIVE BRAINLIEST

xz_007 [3.2K]

Answers:

A) Li

B) Ar

C) Br

D) Ne

E) B

5 0

4 years ago

A car covers a distance of 22.75 km in 17.04 minutes. Use dimensional analysis to calculate its speed in meters/second. Do not e

kati45 [8]

The speed of the car = 22.25 m/s

<h3>Further explanation</h3>

Given

A distance of 22.75 km

Time = 17.04 minutes

Required

The speed (in m/s)

Solution

Speed is the ratio of distance per time

Can be formulated :

v = d/t

v= speed, m/s

d=distance=m

t=time,s

Input the value :

$\tt v=\dfrac{22.75~km}{17.04~minutes}\times \dfrac{1000~m}{1~km}\times \dfrac{1~minute}{60~second}\\\\v=\boxed{\bold{22.25~m/s}}$

3 0

3 years ago

An unconformity is an __ of rock

d1i1m1o1n [39]

An unconformity is a missing layer of rock, in other words an erosion separating two units of rock.

3 0

3 years ago

Identify the oxidizing agent and the reducing agent for the following reaction: Zn(s)+Cu2+(aq)→Zn2+(aq)+Cu(s) Express your answe

Ainat [17]

Answer: oxidizing agent: $Cu^{2+}$ , reducing agent : $Zn$

Explanation: Oxidation-reduction reaction or redox reaction is defined as the reaction in which oxidation and reduction reactions occur simultaneously.

Oxidation reaction is defined as the reaction in which a substance looses its electrons. The oxidation state of the substance increases.

Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced.

For the given reaction:

$Zn(s)+Cu^{2+}(aq)\rightarrow Zn^{2+}(aq)+Cu(s)$

On reactant side:

Oxidation state of zinc = 0

Oxidation state of copper = +2

On product side:

Oxidation state of zinc = +2

Oxidation state of copper = 0

The oxidation state of copper reduces from +2 to 0, it is getting reduced. The substance which itself gets reduced, oxidizes other and is called as oxidizing agent.Thus $Cu^{2+}$ acts as oxidizing agent.

The oxidation state of zinc increases from 0 to +2. Thus, it is getting oxidized and it undergoes oxidation reaction. The substance which itself gets oxidized, reduces other and is called as reducing agent.Thus $Zn$ acts as reducing agent.

3 0

4 years ago

Help help please help help :)​

Help help please help help :)