Starter In pairs discuss everything you remember about titrations:

Slides:

Advertisements

Similar presentations

Titrations and Indicators IB Chemistry Power Points Topic 18 Acids and Bases

Advertisements

IB Chemistry Power Points

Equilibrium in Acid-Base Systems

Titration curves.

 a pH value tells us how much H + is in a solution. It can be defined by: pH = - log[H + ] (log is to base 10). (Also note, square brackets are used to.

Acid-Base Equilibria Common Ion Effect in Acids and Bases Buffer Solutions for Controlling pH Buffer Capacity pH-Titration Curves Acid-Base Titration Indicators.

Acids, Bases and Buffers The Br Ø nsted-Lowry definitions of an acid and a base are: Acid: species that donates a proton Base: species that can accept.

Lecture 152/22/06 Topics due. Neutralization: Acid + Base = Water + Salt pH of neutralized solution? Strong Acid + Strong Base  HCl (aq) + NaOH (aq)

Burette clamp ring stand burette erlenmeyer flask Titration.

A guide for A level students KNOCKHARDY PUBLISHING

213 PHC. Indicators  Describe the indicator theory.  Select a suitable indicator for a particular reaction.  Explain the different stages of strong.

Burette clamp ring stand burette erlenmeyer flask Titration.

Unit 6 – Acids and Bases.  Indicators are dyes that change colour under varying conditions of acidity.  Although not as accurate as instruments such.

Basic acid/base titrations. Types of acid base titration There are four different types of acid/base titrations; 1) Strong acid with strong base. 2) Strong.

Self Ionisation of Water

Acid–Base Titration Curves and Indicators

Strong Acid-Base Titrations Chapter 17. Neutralization Reactions Review Generally, when solutions of an acid and a base are combined, the products are.

Titrations Titrations A. Titrations – is an experimental procedure in which a standard solution is used to determine the concentration of an unknown.

Acid-Base Titration SCH 4U1 Mr. Dvorsky January 17 th 2012.

 Water molecules can function as both acids and bases. One water molecule (acting as a base) can accept a hydrogen ion from a second one (acting as.

ACIDS AND BASES Acid Base Titration A very accurate method to measure concentration. Acid + Base  Salt + Water H + + OH -  H 2 O Moles H + = Moles.

Updates Assignment 06 is due Mon., March 12 (in class) Midterm 2 is Thurs., March 15 and will cover Chapters 16 & 17 –Huggins 10, 7-8pm –For conflicts:

Chapter 17 Additional Aspects of Acid-Base Equilibria

(equimolar amounts of acid and base have reacted)

3 Acids, Bases, and Buffers

1 pH CURVES & INDICATORS How pH indicators work methyl orangephenolphthalein Choosing an appropriate indicator pH curves strong acid strong base strong.

Titrations Main Idea: Titrations are an application of acid-base neutralization reactions that require the use of an indicator.

Indicators for Acid-Base Titrations (Sec. 9-6). transition range needs to match the endpoint pH as closely as possible in order to minimize titration.

Acid-Base Equilibria L.O.: To be able to explain how an indicator works.

Acid-base titrations 4.3 exercise 4.

Acid-Base Indicators The most common acid-base indicators are complex molecules that are themselves weak acids (represented by HIn). They exhibit one color.

1081. y = 1.0 x M [OH - ] = 1.0 x M 1082.

1 Acid-Ionization Titration Curves  An acid-base titration curve is a plot of the pH of a solution of acid (or base) against the volume of added base.

Why do Titration Curves Look Like THAT ???? 1/4/20161.

bjects/3312/ /blb1703.html.

Week 21 © Pearson Education Ltd 2009 This document may have been altered from the original Describe what is meant by a buffer solution. State that a buffer.

Acid-Base Titrations Section Introduction Definition: – In an acid-base titration, a solution containing a known concentration of a base is slowly.

pH CURVES & INDICATORS Richard Grime – Ripon Grammar School

Chapter 15 Acid–Base Equilibria. Section 15.2 Atomic MassesBuffered Solutions Return to TOC Copyright © Cengage Learning. All rights reserved 2 Key Points.

Volumetric analysis. Mole concept map For the reaction A + B  C, where A is the limiting reagent, concentration particles mass volume (gas) MOLE (A)

NEUTRALIZATION, INDICATORS, AND TITRATIONS. NEUTRALIZATION REACTIONS So far we have only looked at acid and base reactions with water Ka and Kb reactions.

Indicator CCC Kei Heep Secondary School F.6 Chemistry by Wong CS Chemistry CE Homepage Chemistry AL Homepage.

Titrations. Standard Solution Sample Solution Burette A titration is a volumetric analysis technique used to find the [unknown] of a sample solution by.

Titrations L.O: To understand how to set up a titration to find the concentration of an unknown acid / alkali.

A titration curve is a graph which shows how the pH of an acid solution changes as a base is added to it, or how the pH of a base solution changes as an.

Kinds of Titrations. Titration of a Strong Acid With A Base As a strong base is titrated into a strong acid, there is just a slight increase in pH until.

Titration  Lab technique commonly utilized to determine an UNKNOWN concentration of a chemical compound with a KNOWN concentration of another chemical.

Acids and Bases. Brønsted-Lowry Theory Brønsted-Lowry describes reactions of acids as involving the donation of a hydrogen ion (H + ) Brønsted-Lowry describes.

213 PHC Dr. Mona AlShehri 5th Lecture. (1) Gary D. Christian, Analytical Chemistry, 6 th edition.

Yr 10 Chemistry Acids and Bases.  Calculate the new concentration if I ADD 200ml of water to 300ml of 2M HCl. Starter.

Obj. finish 17.2, ) The pH range is the range of pH values over which a buffer system works effectively. 2.) It is best to choose an acid with.

Equilibrium in Acid-Base Systems 16.4a: Interpreting pH curves.

18.4 Acid-Base Titrations. Assessment Statement Sketch the general shapes of graphs of pH against volume for titrations involving strong and weak.

Acid-Base Titrations Calculations. – buret to hold the titrant – beaker to hold the analyte – pH meter to measure the pH.

Chapter 17 Section 3. © 2009, Prentice-Hall, Inc. Titration In this technique a known concentration of base (or acid) is slowly added to a solution of.

PH Titration Curves & Indicators. Objectives 1)Review AS understanding of titration calculations for: Reacting volumes & Reactant concentrations 1)Predict,

Acid-Base Equilibria Sections (Unit 18A)

C. Y. Yeung (CHW, 2009) p.01 Titration Curves Acid-Base Eqm (5): Titration Curves Titration Curves Acid-Base Eqm (6): Titration Curves Plotting the Titration.

Acids and Bases Titration curves.

strong acid strong base

INDICATORS & TITRATION CURVES

Neutralisation Lesson 7.

(Acid/Base neutralization)

pH Curves Strong Acid/Strong Base

Acids and Bases Titration Curves.

How can use titrations to work out the concentration of a chemical

What are acids and bases?. Monoprotic and diprotic acids Many acids are called monoprotic acids. This means that they only donate one mole of protons.

Presentation transcript:

Starter In pairs discuss everything you remember about titrations: How they are carried out. What are indicators for? You carry out a titration of a 25 cm3 acid solution (c= 0.5 moldm-3) with a 1 mol dm-3 solution of NaOH. Calculate the number of moles of acid after the addition of 10 cm3 of NaOH

Neutralisation Interpret and sketch acid-base pH curves for strong and weak acid and bases. Explain the choice of suitable indicator for acid-base titration

Simulation: http://users.skynet.be/eddy/titratie.swf Strong acid/ strong base Leave out

weak acid (CH3COOH) v. strong alkali (NaOH) pH curves Types There are four types of acid-base titration; each has a characteristic curve. strong acid (HCl) v. strong base (NaOH) weak acid (CH3COOH) v. strong alkali (NaOH) strong acid (HCl) v. weak base (NH3) weak acid (CH3COOH) v. weak base (NH3) In the following examples, alkali (0.1M) is added to 25cm3 of acid (0.1M) End points need not be “neutral‘ due to the phenomenon of salt hydrolysis

Equivalence point: the point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution

strong acid (HCl) v. strong base (NaOH)

Equivalence point is the centre of the vertical section of the titration curve.

Titration curve for a strong acid–strong base titration

strong acid (HCl) v. strong base (NaOH) pH 1 at the start due to 0.1M HCl (strong monoprotic acid)

strong acid (HCl) v. strong base (NaOH) Very little pH change during the initial 20cm3 pH 1 at the start due to 0.1M HCl (strong monoprotic acid)

strong acid (HCl) v. strong base (NaOH) Very sharp change in pH over the addition of less than half a drop of NaOH Very little pH change during the initial 20cm3 pH 1 at the start due to 0.1M HCl (strong monoprotic acid)

strong acid (HCl) v. strong base (NaOH) Curve levels off at pH 13 due to excess 0.1M NaOH (a strong alkali) Very sharp change in pH over the addition of less than half a drop of NaOH Very little pH change during the initial 20cm3 pH 1 at the start due to 0.1M HCl (strong monoprotic acid)

strong acid (HCl) v. weak base (NH3) Curve levels off at pH 10 due to excess 0.1M NH3 (a weak alkali) Sharp change in pH over the addition of less than half a drop of NH3 Very little pH change during the initial 20cm3 pH 1 at the start due to 0.1M HCl

weak acid (CH3COOH) v. strong base (NaOH) Curve levels off at pH 13 due to excess 0.1M NaOH (a strong alkali) Sharp change in pH over the addition of less than half a drop of NaOH Steady pH change pH 4 due to 0.1M CH3COOH (weak monoprotic acid)

weak acid (CH3COOH) v. weak base (NH3) Curve levels off at pH 10 due to excess 0.1M NH3 (a weak alkali) NO SHARP CHANGE IN pH Steady pH change pH 4 due to 0.1M CH3COOH (weak monoprotic acid) Types

4.3 exercise 4

Indicator

Hin = H+ + In-

pH colour ranges for some common indicators 19

COLOUR CHANGES OF SOME COMMON INDICATORS Watch demo? Why do you get a different result with a different indicator? phenolthalein Methyl orange COLOUR CHANGES OF SOME COMMON INDICATORS pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 METHYL ORANGE CHANGE LITMUS CHANGE PHENOLPHTHALEIN CHANGE

Indicator change colours around +- 1 unit of pH from their end point. An indicator has to be chosen so that their end point is as close as the pH value of the titration’s equivalence point.

So the colour of the indicator changes over the pH range pKIn  1 HIn(aq) H+(aq) + In¯(aq) So the colour of the indicator changes over the pH range pKIn  1

Which indicator is the best? The best indicator is C because it is closest to the mid point of the vertical pH change, but B and D would work as well. A and E will not change colour because they are outside the range of pH change

What happens when you titrate Na2CO3 with HCl? Simulation What happens when you titrate Na2CO3 with HCl? What happens when you titrate H3PO4 with NaOH? 4.3 exercise 4

Choice of indicators for titrations Teacher demo titration of NaOH/ acetic acid. Figure 3 in page 43. 2 titrations (1 with methyl orange, another with phenolphthalein). 4.3 exercise 4

Must change immediately in the required pH range Acid-base indicators Must have an easily observed colour change. Must change immediately in the required pH range over the addition of ‘half’ a drop of reagent. To be useful, an indicator must change over the “vertical” section of the curve where there is a large change in pH for the addition of a very small volume of alkali. The indicator used depends on the pH changes around the end point - the indicator must change during the ‘vertical’ portion of the curve. In the example, the only suitable indicator is PHENOLPHTHALEIN. PHENOLPHTHALEIN LITMUS METHYL ORANGE Extra slides from this one

COLOUR CHANGES OF SOME COMMON INDICATORS Acid-base indicators Must have an easily observed colour change. Must change immediately in the required pH range over the addition of ‘half’ a drop of reagent. COLOUR CHANGES OF SOME COMMON INDICATORS pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 METHYL ORANGE CHANGE LITMUS CHANGE PHENOLPHTHALEIN CHANGE

weak acid (CH3COOH) v. strong alkali (NaOH) pH curves Types There are four types of acid-base titration; each has a characteristic curve. strong acid (HCl) v. strong base (NaOH) weak acid (CH3COOH) v. strong alkali (NaOH) strong acid (HCl) v. weak base (NH3) weak acid (CH3COOH) v. weak base (NH3) In the following examples, alkali (0.1M) is added to 25cm3 of acid (0.1M) End points need not be “neutral‘ due to the phenomenon of salt hydrolysis

strong acid (HCl) v. strong base (NaOH)

strong acid (HCl) v. strong base (NaOH) pH 1 at the start due to 0.1M HCl (strong monoprotic acid)

strong acid (HCl) v. strong base (NaOH) Very little pH change during the initial 20cm3 pH 1 at the start due to 0.1M HCl (strong monoprotic acid)

strong acid (HCl) v. strong base (NaOH) Very sharp change in pH over the addition of less than half a drop of NaOH Very little pH change during the initial 20cm3 pH 1 at the start due to 0.1M HCl (strong monoprotic acid)

strong acid (HCl) v. strong base (NaOH) Curve levels off at pH 13 due to excess 0.1M NaOH (a strong alkali) Very sharp change in pH over the addition of less than half a drop of NaOH Very little pH change during the initial 20cm3 pH 1 at the start due to 0.1M HCl (strong monoprotic acid)

strong acid (HCl) v. strong base (NaOH) PHENOLPHTHALEIN LITMUS METHYL ORANGE Any of the indicators listed will be suitable - they all change in the ‘vertical’ portion

strong acid (HCl) v. weak base (NH3) Curve levels off at pH 10 due to excess 0.1M NH3 (a weak alkali) Sharp change in pH over the addition of less than half a drop of NH3 Very little pH change during the initial 20cm3 pH 1 at the start due to 0.1M HCl

strong acid (HCl) v. weak base (NH3) PHENOLPHTHALEIN LITMUS METHYL ORANGE Only methyl orange is suitable - it is the only one to change in the ‘vertical’ portion

weak acid (CH3COOH) v. strong base (NaOH) Curve levels off at pH 13 due to excess 0.1M NaOH (a strong alkali) Sharp change in pH over the addition of less than half a drop of NaOH Steady pH change pH 4 due to 0.1M CH3COOH (weak monoprotic acid)

weak acid (CH3COOH) v. strong base (NaOH) PHENOLPHTHALEIN LITMUS METHYL ORANGE Only phenolphthalein is suitable - it is the only one to change in the ‘vertical’ portion

weak acid (CH3COOH) v. weak base (NH3) Curve levels off at pH 10 due to excess 0.1M NH3 (a weak alkali) NO SHARP CHANGE IN pH Steady pH change pH 4 due to 0.1M CH3COOH (weak monoprotic acid) Types

weak acid (CH3COOH) v. weak base (NH3) PHENOLPHTHALEIN LITMUS METHYL ORANGE NOTHING SUITABLE There is no suitable indicator- none change in the ‘vertical’ portion. The end point can be detected by plotting a curve using a pH meter.