The great chem-mystery PDF So if we know how

concentration of sodium hydroxide. The chemical reaction between acetic acid and sodium hydroxide is given below: CH3COOH(aq) + NaOH(aq) ? CH3COONa(aq) +

Lecture 15

Titrations are based on the acid/base neutralization reaction. CH3COOH (aq) + NaOH (aq). CH3COONa (aq) + H2O (l). CH3COOH (aq) + OH-. (aq). CH3COO-.

Acid-Base Chemistry Brønsted-Lowry Acids & Bases

CH3COOH(aq) + H2O(l) ? CH3COO-(aq) + H3O+(aq) acid base conjugate Step 1: since NaOH is a strong base ... exchange reaction

E17 Acid Ionisation Constant of Acetic Acid from Titration Curve

It is called the half-equivalence point. The pH at this point should equal the pKa value for acetic acid. A plot of pH against the amount of added NaOH is

Sample Exercise 17.1 Calculating the pH When a Common Ion is

Solve: Stoichiometry Calculation: The OH– provided by NaOH reacts with CH3COOH the weak acid component of the buffer. Prior to this neutralization reaction

CHM 2046 Answer Key – Practice Quiz 2 Answer all questions. Be

base-ionization equation for CH3COO- in water. CH3COO- (aq) + H2O (l) ? CH3COOH (aq) (b) (13 points) What is the final pH after 10.0 mL of 0.200 M NaOH.

CHEM1102 Answers to Problem Sheet 8 1. (a) The titration is a 1:1

As acetic acid is a weak acid [H3O+] must be calculated: CH3COOH (iv) The addition of 50.0 mL of 0.100 M NaOH corresponds to the equivalence.

Buffer Solutions Buffer Solutions

acetic acid (remember that acids react with bases). CH3COOH(aq) + H2O ? CH3COO-(aq) + H3O+(aq) ? Henderson-Hasselbach Equation ... mL NaOH added.

Lab 25. Acid-Base Titration and Neutralization Reactions: What Is

For example when sodium hydroxide is added to acetic acid

The great chem-mystery

So if we know how much NaOH we have added (the burette readings tell us) then we can calculate how much acetic acid was in the flask. The equation for the

The Common-Ion Effect - College of Science

1 8 x 10-5 = [CH3COO-][H3O+]/[CH3COOH] M = amount of acetic acid that dissociates then X M of H3O+ and CH3COO- ions are formed 1 8 x 10-5 = (X + 2 5)(X)/(0 5 - X) Can we use the shortcut to the quadratic? 0 5M acetic acid / 1 8 x 10-5 = 27777 (which is greater than 100) 1 8 x 10-5 = (X + 2 5)(X)/(0 5 - X) ? (2 5)(X)/(0 5) 9 0 x 10-6 = 2 5X

How do you balance the equation CH3COOH + NaOH?

Balance the equation CH3COOH + NaOH = CH3COONa + H2O using the algebraic method. Label each compound (reactant or product) in the equation with a variable to represent the unknown coefficients.

What is the chemical formula for the reaction between CH3COOH and NaOH?

CH3COOH + NaOH = NaCH3COO + H2O might be a redox reaction. Use the calculator below to balance chemical equations and determine the type of reaction (instructions). To balance a chemical equation, enter an equation of a chemical reaction and press the Balance button. The balanced equation will appear above.

What is the product of CH3COOH + NaOH?

The mixture of acetic acid (CH3COOH) and sodium hydroxide (NaOH) works as a solution of weak acid and strong base and the products of this reaction are sodium acetate (CH3COONa) and water (H2O). This is an example of acid neutralization reaction with weak acid and strong base.

What happens when CH3COOH and NaOH are mixed together?

The mixture of acetic acid (CH3COOH) and sodium hydroxide (NaOH) works as a solution of weak acid and strong base and the products of this reaction are sodium acetate (CH3COONa) and water (H2O). This is an example of acid neutralization reaction with weak acid and strong base. Let’s focus on the following topics related to the above subjects.

MEOW Chemistry Student Resource

Download this and other mathematics teaching resources: https://www.jcu.edu.au/maths -hub. Copying, sharing and adaptation of this material.

The great

chem-mystery Are we being swindled? How can we find out exactly what and how much is in the products we buy? Supermarkets are full of labels and advertising trying desperately to get your attention and pocket

money. In this increasingly health-conscious world, how can you know exactly what is in the foods you

buy? How can you be sure that sneaky marketers or sly food manufacturers aren't pulling the wool over your eyes? The answer is - chemistry. Chemistry is the study of matter, its properties, and how and why substances combine and separate.

Chemists often use a technique called titration. By adding known concentrations of specific chemicals to

unknown mixtures, and by using the rules of chemistry, we can work backwards to discover exactly what

was in the original unknown mixture. Did you know? Two New Zealand schoolgirls rumbled one of the world's biggest food a nd dr ug c o m pa ni e s a f te r th e i r s c h o o l s c i e nc e e x pe r i m e nt fo un d tha t their ready-to-drink Ribena contained almost no trace of vitamin C,

despite the product claiming plenty of it. The company behind Ribena was forced to pay big fines and change its advertising.

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The Experiment - Acetic Acid Titration!

How much acetic acid is in different vinegar brands?

In this experiment, you will use titration to work out exactly how much acetic acid is in three different

brands of vinegar, and thus check if the brands are telling the truth.

Theory Practice

Letter symbols are used to represent atoms.

The symbols are either a capital letter only or

a capital letter followed by a lower case letter H is the symbol for hydrogen

O is the symbol for oxygen

C is the symbol for _______

______

Na is the symbol for ________

_____

All atoms have a mass called the

atomic mass. The units are called atomic mass units (amu) The atomic mass for

H is 1 amu

O is 16 amu

C is ______ amu

Na is _____ amu

Compounds are a combination of more than

one atom NaOH is sodium hydroxide CH

3COOH is acetic acid (the common name for this

chemical is ____________ ).

The subscript number means that there are 3

hydrogen atoms

The mass of a compound is called the

molecular mass. The molecular mass is the addition of the masses of all atoms in that compound The molecular mass of:

NaOH is 23+16+1= ______ amu

3COOH is 12+3+12+16+16+1= _____ amu

Amounts of chemical compounds are

measured in quantities called moles. One mole of a compound has the same number of particles as one mole of another compound. 1 mole of a compound = 6.02 x 10 23
particles (It's a little bit like the word "dozen", 1 dozen eggs =

12 eggs

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Theory Practice

One mole is simply the atomic mass or

molecular mass in grams. One mole of

NaOH is 23+16+1=_______ g

3COOH is 12+3+12+16+16+1=_______ g

The strength of a chemical solution is called

its concentration and is the number of moles in a known volume. The concentration of NaOH solution that you will use today is: _________________ moles per litre (mol. L -1 (Think of how a cordial drink can be weak or strong depending on how much cordial we add to the glass of water)

Acids combine with bases in a reaction called

neutralisation . Chemical equation for the reaction you will use today:

1ܪܱܽܰ+1ܪܥ

ܪܱܱܥ ՜ 1ܪܥ

ܱܱܽܰܥ+ 1ܪ

The equivalence point of a neutralisation

reaction is when the acid and base are present in equal quantities.

How many moles of NaOH will neutralise 1 mole of

3COOH ? ______________

This can be written as a mole ratio:

NaOH : CH3COOH 1 : 1

Today you will perform a

titration that will determine how much acid is present in your sample of vinegar by determining the equivalence point.

This will be when just enough NaOH is added to

neutralise the CH

3COOH in your sample.

An indicator is added to the vinegar flask that wi ll change colour when this happens.

Because we know the concentration of NaOH we can

work backwards to find the unknown concentration of CH 3COOH Download this and other mathematics teaching resources: https://www.jcu.edu.au/maths-hub.

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Procedure

You will be split into small groups and provided with a burette, and conical flask, as well a s a brand of vinegar (A or B) and a sodium hydroxide (NaOH) solution. The demonstrators will show you how to use the equipment.

Burette: Pipette: Conical flask:

Safety Note: Sodium hydroxide solutions are corrosive to clothing and the skin.

If there

are any spillages, inform the demonstrator immediately.

1. Write the brand of vinegar your group is using into Table 1.

2. You will find a burette filled with a sodium hydroxide (NaOH) solution. Record the concentration

(strength) of NaOH in Table 1.

3. Read the level of NaOH in the burette and record it in Table 1 in the column marked 'Initial Burette

reading (ml)'.

4. You will also find four conical flasks each containing 5 mL of the prepared vinegar solution and 50 mL of water. The prepared vinegar solution was diluted to 1/10 of the original vinegar from the supplier.

5. Add approximately 3 drops of the phenolphthalein indicator to the vinegar solution.

6. In the first titration, add the sodium hydroxide (NaOH) solution to the vinegar solution in 0.5ml steps.

Continue carefully until the first moment a pale pink colour of the indicator doesn't disappear after

swirling. This signals the approximate end point of the titration.

7. In the next 3 titrations, add the sodium hydroxide (NaOH) solution to the vinegar solution in 0.5ml steps.

Continue carefully until you reach 1 mL from the previous titration (if you measured 10 mL in the first

titration then stop after adding 9 mL).

8. Add the sodium hydroxide (NaOH) solution one drop at a time of into the vinegar solution, swirling after

each addition. Continue carefully until the first moment a pale pink colour of the indicator doesn't disappear after swirling. This signals the end point of the titration.

9. Read the new level of NaOH in the burette. Record in Table 1 in the column marked 'Final Burette

reading (ml)'.

10. Repeat the previous steps 8-10 two more times, and record your burette values in Table 1.

11. Find the average of your three values, and record in Table 1. Remember to convert to litres (L).

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Table 1: Titration Data

Vinegar Brand:

NaOH concentration:

Titration number:

INITIAL

Burette reading

(ml) FINAL

Burette reading

(ml)

Titre volume (ml)

Approximate:

2 Average Titre

volume (L)* 3

Average Titre Volume (mL):

*Volume (L) = Volume (mL) ÷ 1000

Calculations

The equivalence point is when the NaOH added has neutralised all of the CH3COOH in the flask (the end

point of the titration, where the colour turned slightly pink). The equation shows that this occurs when

the acid and the base are present in quantities that have a 1:1 ratio. For every 1 mole of Sodium Hydroxide (NaOH), there is 1 mole of Acetic Acid (CH

3COOH). So if we know how much NaOH we have

added (the burette readings tell us) then we can calculate how much acetic acid was in the flask. The equation for the reaction involved in this titration is:

1. At the equivalence point, what volume (L) of NaOH was added to the flask?

2. What is the concentration of the NaOH solution?

The number of moles of NaOH can be calculated because you have the volume and the concentration: Download this and other mathematics teaching resources: https://www.jcu.edu.au/maths-hub.

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3. What is the number of moles of NaOH added to the flask?

Calculation: In words:

Number of moles of acetic acid is the same as the number of moles of NaOH calculated above.

4. Therefore, what is the number of moles of acetic acid (CH3COOH) in the flask?

5. What volume (L) of acetic acid was in the flask at the start of the titration?

The concentration of acetic acid (final value and units) is calculated from the equation

6. What is the concentration of the vinegar (acetic acid (CH3COOH)) solution?

Calculation: In words:

The concentration of your vinegar solution was diluted to 1/10 of the original vinegar purchased from

the company.

7. What is the concentration of the original vinegar (acetic acid (CH3COOH)) in the bottle?

Calculation: In words:

8. Was your brand of vinegar telling the truth about its acetic acid concentration?

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Want to make your life a little easier?

Check out these chemistry life hacks: https://www.youtube.com/watch?v=mAqJmEjCy4E

Challenge

A second titration is performed. This time Sulphuric Acid (H2SO4), which is battery acid, is titrated with

Sodium Hydroxide (NaOH). The reaction equation is:

1H2SO4 + 2NaOH ՜ͳ2SO4 + 2H2O

1. At the equivalence point, what is the ratio between moles of H2SO4 and moles of NaOH?

If the

2SO4 has a known concentration of 2.5 mol/L, and the titre volume was found to be 0.01 L, then

calculate:

2. How many moles of H2SO4 were used in the titration?

3. How many moles of NaOH were used in the titration? (Hint: use the ratio from Q1)

The original volume of NaOH used in the titration is known to be 0.025 L:

4. What is the concentration of the NaOH?

Puzzle

Using only the numbers 1, 7, 7, 7 and 7, and the addition, subtraction, multiplication and division operations, how close to the number 100 can you get? (Hint: you may need to use brackets)

To gain

EXP and level-up your mathematician, email your answers to the Challenge and Puzzle questions to Dr Greg at Gregory.Boyle@my.jcu.edu.au.

Q: Why

are chemists great for solving problems?

A: Because they have all the solutions!

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[PDF] The great chem-mystery So if we know how

How do you balance the equation CH3COOH + NaOH?

What is the chemical formula for the reaction between CH3COOH and NaOH?

What is the product of CH3COOH + NaOH?

What happens when CH3COOH and NaOH are mixed together?

MEOW Chemistry Student Resource

The great

Copying, sharing and adaptation of this material.

Page 2 of 7

The Experiment - Acetic Acid Titration!

Theory Practice

Letter symbols are used to represent atoms.

The symbols are either a capital letter only or

O is the symbol for oxygen

C is the symbol for _______

Na is the symbol for ________

All atoms have a mass called the

H is 1 amu

O is 16 amu

C is ______ amu

Na is _____ amu

Compounds are a combination of more than

3COOH is acetic acid (the common name for this

The subscript number means that there are 3

The mass of a compound is called the

NaOH is 23+16+1= ______ amu

3COOH is 12+3+12+16+16+1= _____ amu

Amounts of chemical compounds are

12 eggs

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Page 3 of 7

Theory Practice

One mole is simply the atomic mass or

NaOH is 23+16+1=_______ g

3COOH is 12+3+12+16+16+1=_______ g

The strength of a chemical solution is called

Acids combine with bases in a reaction called

1ܪܱܽܰ+1ܪܥ

ܪܱܱܥ ՜ 1ܪܥ

ܱܱܽܰܥ+ 1ܪ

The equivalence point of a neutralisation

How many moles of NaOH will neutralise 1 mole of

3COOH ? ______________

This can be written as a mole ratio:

Today you will perform a

This will be when just enough NaOH is added to

3COOH in your sample.

Because we know the concentration of NaOH we can

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Page 4 of 7

Procedure

Burette: Pipette: Conical flask:

If there

1. Write the brand of vinegar your group is using into Table 1.

2. You will find a burette filled with a sodium hydroxide (NaOH) solution. Record the concentration

3. Read the level of NaOH in the burette and record it in Table 1 in the column marked 'Initial Burette

4. You will also find four conical flasks each containing 5 mL of the prepared vinegar solution and 50 mL of water. The prepared vinegar solution was diluted to 1/10 of the original vinegar from the supplier.

5. Add approximately 3 drops of the phenolphthalein indicator to the vinegar solution.

6. In the first titration, add the sodium hydroxide (NaOH) solution to the vinegar solution in 0.5ml steps.

7. In the next 3 titrations, add the sodium hydroxide (NaOH) solution to the vinegar solution in 0.5ml steps.

8. Add the sodium hydroxide (NaOH) solution one drop at a time of into the vinegar solution, swirling after

9. Read the new level of NaOH in the burette. Record in Table 1 in the column marked 'Final Burette

10. Repeat the previous steps 8-10 two more times, and record your burette values in Table 1.

11. Find the average of your three values, and record in Table 1. Remember to convert to litres (L).

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Page 5 of 7

Table 1: Titration Data

Vinegar Brand:

NaOH concentration:

Titration number:

INITIAL

Burette reading

Burette reading

Titre volume (ml)

Approximate:

2 Average Titre

Average Titre Volume (mL):

Calculations

3COOH). So if we know how much NaOH we have

1. At the equivalence point, what volume (L) of NaOH was added to the flask?