How to make a titration curve in excel

I. Introduction

A titration curve is a graph of how some quantity of a solution (the dependent variable, y) transforms through the addition of well-known quantities of a titrant of known concentration (the independent variable, x). With acid-base titrations, the dependent variable is the pH of the solution; and the titration curve answers the question “How does the pH of the solution change through the addition of the titrant?” The neutralization of a solid base via a strong acid involves equilibrium easily, so this titration deserve to be done via a sigmoidal titration curve.

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The building and construction of an acid-base titration curve entails thinking via exactly how the pH is identified in the time of each various phase of the process:

Before the enhancement of any type of titrant Pre-equivalence phase Equivalence allude Post-equivalence phase.

As you think with how the pH is established at these different times in the titration, you will certainly check out exactly how to construct the attributes necessary to do the calculations for each phase. After that, we will usage the pH and volume of titrant indevelopment to construct the titration curve.


II. The Problem

Let’s say that you want to titrate a 50.00 mL aliquot of 0.1000 M NaOH via a 0.1000 M solution of HCl and then construct the resulting titration curve. Using an Excel spreadsheet, calculate the pH of the solution after the addition of 0.00, 10.00, 25.00, 40.00, 45.00, 49.00, 49.50, 50.00, 50.50, 51.00, 55.00, 60.00, 75.00, and also 90.00 mL of titrant; and also then prepare a titration curve from the data.


III. Setting Up the Spreadsheet


A. Data and also Functions

1. Reference Info

What execute we know in the beginning that will be relevant in an acid-base titration? The volume and also the concentration of the solution being titrated, the concentration of the analyte, and also the ion-product continuous for water (Kw) are four pieces of indevelopment that I would usage.

Enter the complying with labels: VNaOH, mL in cell A3, in cell A4, mmol NaOH in cell A5, in cell A6, and also Kw in cell D3. You have the right to kind the value for 4 of these in the cell to the appropriate of the label: 50.00 in cell B3, 0.1000 in cell B4, 0.1000 in cell B6, and 1.00E-14 in cell D3. The mmol NaOH (which will certainly be the exact same at each allude in the titration) have to neverthemuch less be calculated, so enter the attribute required for this value in cell B5.

2. The Independent Variable (x)

The independent variable is the variable that we change by design: in this situation, that’s the boosting volumes of titrant included at various points in the titration.

Enter the label VHCl, mL into cell A8, and also then enter the volumes of titrant included into cells A9-A22. Go into the label mmol HCl right into cell B8, enter the function essential to calculate this right into cell B9, and also then drag it down through cell B22. (Remember to format the cells for the correct variety of digits past the decimal.)

3. The Functions that Reveal the Dependent Variable (y)

The dependent variable of interest is the pH of the solution, however the calculation of pH requires various preliminary calculations in the time of the various phases of a titration. Think about the things we need to understand for each phase:

Identify What’s in the Flask.

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Understand also the Neutralization Reaction. Calculate the pH Based on What Remains after the Neutralization.

Get in the adhering to labels: mmol NaOH in cell C8, mmol HClexcess in D8, Vtotal, mL in cell E8, in cell F8, in cell G8, pOH in cell H8, and also pH in cell I8.

Before the Addition of any type of Titrant

Before the enhancement of any type of titrant, what’s in the flask, and also how is it pertained to the pH of the solution?

Pre-Equivalence Phase

If you were developing a titration experiment, you would certainly desire to have actually numerous data points in the pre-equivalence phase and also in the post-equivalence phase. In addition, you would certainly desire to room some of them closer together just before and simply after the equivalence suggest. In this titration, 50.00 mL of titrant is compelled to reach the endallude. How did I recognize that?

Remember the BCA (Before Change After) chart? We will certainly use what we learned tbelow to construct the attributes that will eventually calculate the pH. Notice that as the titration proceeds, the mmol OH-1 will decrease bereason of neutralization of the NaOH and dilution of the original solution.

Why is it that the functions you wrote for the initial points are the only ones you require for the pre-equivalence phase? Drag them down via the rows that correspond to the pre-equivalence phase (yet no farther). Keep in mind that there’s nopoint in columns C and G at this suggest.

Equivalence Point

At the equivalence allude, every one of the analyte has reacted with the titrant; namong the reactants remajor. (We have currently talked around the volume of titrant compelled to reach the equivalence suggest.) At this point, what determines the pH?

Post-Equivalence Phase

What’s going on in the solution once you acquire past the equivalence point? What determines the pH?


B. Spreadsheet Documentation and also Details

Enter the label Spreadsheet Documentation right into cell A24, and also then complete this section as before. Remember to encompass borders, row/column headings, and a title.


IV. Generating the Titration Curve

The generation of the titration curve is a function of Excel. Create the graph y vs.

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x to view what this connection looks favor, and insert this graph into your spreadsheet.


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