Standard solutions and acid-base titration techniques

• Standard solution


  A standard solution is a solution of known concentration.
• Making a standard solution


  Measure, using a balance, the mass of solid required. Transfer this to a volumetric flask and rinse the remaining weighing bottle content (with distilled water) into the flask so no solid is lost. Add a volume of distilled water to dissolve the solid. Swirl to mix. Then add more distilled water up to the line on the volumetric flask. Invert multiple times to mix.
• Weighing by difference technique


  It is a method to weigh materials accurately. Mass of substance = Mass of weighing dish and substance - Mass of dish after substance has been transferred.
• Equipment for titration


  A pipette and pipette filler are used to accurately measure out the volume of a reactant before transferring it to a conical flask. A burette is used to add small volumes of one reactant to the other reactant (until the reaction has reached completion).
• Carrying out a titration


  Once the pipette has been used to place one reactant into the conical flask, fill the burette with the other reactant. Record initial volume. Add a few drops of indicator to the conical flask. Open the burette tap and allow the reactant to flow into the conical flask, swirling it to mix the contents. Close the burette tap once the expected colour change occurs. Use a white tile so the colour change is easy to identify. Record final burette volume. Repeat until you get concordant results, then calculate a mean titre.
• Acid-base indicators


  To detect when a reaction reaches completion, usually by the presence of a colour change.
• Concordant results


  Titres that are within 0.1 cm3 of each other.
• Bunsen burner hazard


  Burns. Keep away from flammable chemicals and away from the edge of the desk.
• Chemical hazards


  May be an irritant or corrosive, causing irritation to skin, eyes, lungs. May be toxic. May be flammable. Handle with care and while wearing gloves. Wear eye protection. Keep away from the edge of the desk and from an open flame. Don't ingest.
• Glassware hazards


  May break and cut you. Handle with care. Keep away from edge of the desk.