Acid-Base Titrations & Standard Solutions | A-level Chemistry | OCR, AQA, Edexcel

Acid-Base Titrations & Standard Solutions in a Snap!

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The key points covered in this video include:
1. What are Titrations?
a) Titration Process
b) Titration Calculations
2. An Introduction to Standard Solution: Making Standard Solutions
3. Titration Calculations

What are Titrations?

Form of volumetric analysis. Known volume and concentration of a solution is reacted with a measured volume of a solution. Can be used to find chemical ‘unknowns’. Concentration, Molar Mass, Formula, Water of Crystallisation

Standard Solution

Solution with a known concentration. Used in titrations.

Titration Process

1. Using a pipette, add a measure volume, x, to a conical flask. 2. Add a suitable indicator to the flask. 3. Fill the burette with the other solution, y. 4. Open the valve on the burette to allow a small quantity of y to flow into the flask of x. Repeat until the end-point is reached. Measure the volume of y that has been added. 7. Calculate the unkowns.

What are Standard Solutions?

Standard solutions are solutions of a known concentration. Used in titrations. Allow us to calculate unknowns.

Reminder: Solvent and Solute

Concentration: How much solute is dissolved in a given volume of solvent.

Making a Standard Solution: Method

Step 1. Carefully weigh out the required mass of your solute. Step 2. Dissolve the solute in your chosen solvent in a beaker. Step 3. Transfer your solution to a volumetric flask. Rinse the beaker with the initial solvent, adding the washings into the volumetric flask. Step 4. Add some of your solvent to the volumetric flask. Make sure not to fill up to the graduation line. Step 5. Add solvent, drop by drop, until the bottom of the meniscus is sitting on the line. Do not allow the solution to fill above the line. Step 6. Mix solution thoroughly. Invert flask multiple times.

Making a Standard Solution: Initial Calculations

Step 1: Work about the number of moles required. Step 2: Calculate the Molar Mass of the required substance. Step 3: Calculate the mass of the substance that is required.

Making a Standard Solution: Initial Calculations

250cm^3 solution of NaOH. 0.1 mol dm^-3 Step 1: Number of moles required. Step 2: Calculate the Molar Mass. Step 3: Calculate the mass required.

Titration Analysis and Calculations

In general, our calculations can follow certain steps. Calculations can be used to find unknowns. These could be: Concentration of the solution. Molar Mass. Many others! Exam questions will usually guide you through. Small steps.

Calculation: Unknown Concentration

25.0cm^3 of 0.1mol dm^-3 of a base, NaOH, is titrated with 22.5cm^3 of an acid, HCl. What is the concentration of the acid involved in this titration? Step 1: Reaction Equation. Step 2: Calculate the amount, in mol, of Base that has reacted. Step 3: Calculate the amount, in mol, of acid, that was used. Step 4: Calculate the Concentration.

Calculation: Unknown Molar Mass

1.5g of an acid was dissolved in water, in order to make a solution with a volume of 250cm^3. 25.0cm^3 of a solution of this acid, HX, was titrated with 22.5cm^3 of a base, NaOH, which had the concentration of 0.1mol dm^-3. What is the molar mass of the acid involved in this titration? Step 1: Reaction Equation. Step 2: Calculate the amount, in mol, of Base that has reacted. Step 3: Calculate the amount, in mol, of acid, that was used to make the initial solution. Step 4: Calculate the Molar Mass of the Acid.