Loading presentation...

Present Remotely

Send the link below via email or IM

Copy

Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.

DeleteCancel

Determination of Calcium Carbonate in Toothpaste

No description
by

Sean Choon

on 11 February 2014

Comments (0)

Please log in to add your comment.

Report abuse

Transcript of Determination of Calcium Carbonate in Toothpaste

Determination of Calcium Carbonate in Toothpaste
Overview
Introduction

Theory

Procedure

Results and Calculations

Discussion

Conclusion
What is calcium carbonate?
Theory
Why is back titration used?

Main ingredients in toothpaste

Chemical reactions involved
Results and Calculations
Discussion
Conclusion
A chemical compound consisting of 1 atom of calcium, 1 atom of carbon, bonded with 3 atoms of oxygen.

White solid at room temperature, odourless, non-toxic

>4% of the earth’s crust


Calcium carbonate powder (Walker, 2005)
What is back titration?
A “reverse” method of titration used to obtain unknown concentration of analyte

Reacted with an excess amount of known reagent

Titrated with a second reagent

Excess of reagent in first reaction can be found

Main ingredients in toothpaste

Fluoride Compounds

Emulsifier

Abrasives

Why is back titration used
Analyte (calcium carbonate) is
insoluble in water

Cannot be titrated normally

Industrial uses

Chemical reactions involved
CaCO3 + 2HCl → CaCl2 + H2O + CO2

Calcium carbonate reacting with excess hydrochloric acid



NaOH + HCl → NaCl + H2O

Sodium hydroxide reacting with unreacted excess hydrochloric acid

Introduction
What is calcium carbonate?

What is back titration?
Procedure
Figure 1: Taking sample of toothpaste (Ifran Shamal, 2014)
Figure 2: Mixing toothpaste and hydrochloric acid (Choon, 2014)
Figure 3: Solution heated over a hot plate (Koh, 2014)
Figure 4: Addition of methyl orange indicator to the mixture (Choon, 2014)
Figure 5: Colour of the solution before titration (Choon, 2014)
Figure 6: Titration setup (Koh, 2014)
Figure 7: Swirling the mixture during titration (Choon, 2014)
Figure 8: Colour of the solution after titration (Ifran Shamal, 2014)
Analysis of result

Sources of errors

Precautions

Ways to improve the results
Analysis of result
Toothpaste generally contains 20% calcium carbonate as an abrasive. (Loos n.d.; Evans n.d.).

The four results obtained from the experiment were relatively close. This means that the results obtained were reliable and constant.

The average concentration of calcium carbonate obtained was 24.13%.


Sources of errors
During:

Taking of toothpaste

Heating

Titration

Precautions
Ways to improve the results
Using bromothymol blue as an indicator

Placing a cotton wool on the filter funnel
Ensuring that there is no transfer of solution in and out of the flask during rinsing.

Using a homogenous toothpaste
Purpose

Results

Discovery
Purpose
Determination of calcium carbonate in toothpaste
Results
The average result obtained was 24.13%.

Close to the literature value of 20%.

Might not be the most accurate.

Discovery
Back titration is efficient

The toothpaste (aquafresh) contain approximately 20% calcium carbonate as an abrasive.

Methyl orange is not suitable as an indicator.
Weight of toothpaste =
0.1637g
Initial burette reading =
0.10mL
Final burette reading =
9.90mL
Volume of NaOH used
= 9.90mL – 0.10mL
= 9.80mL

V HCl (excess)= 0.08M X 9.80mL / 0.16M
=
4.90mL

V HCl (reacted)= 10mL – 4.90mL
=
5.10mL


Moles of HCl = 0.16M X 0.0051L
=
0.000816mol

Moles of CaCO3 = 0.000816mol /2
=
0.000408mol

Mass of CaCO3 = 0.000408mol X 100g/mol
=
0.0408g

Concentration of calcium carbonate
Percentage of CaCO3 in toothpaste = 0.0408g / 0.1637g X 100%
=
24.92364081%
=
24.92%

Salmon (Aquabounty, 2014)
Full transcript