2214948
Description
Flashcards by Georgi Georgieff, updated more than 1 year ago
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Created by Georgi Georgieff
over 9 years ago
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| Question | Answer |
| What is a Primary Standard | A substance used in volumetric analysis that is of such high purity and stability that it can be used to prepare a solution of accurately known concentration |
| Conditions for a primary standard | Purity Accurate concentration Free from moisture Stable and unaffected by air Readily soluble in distilled water High molar weight solid Reacts instantaneously |
| Step 1 for a titration | Preparing the burette |
| Steps for preparing a Burette | 1) Clean with distilled water 2) Rinse with the unknown acid/base 3) Use funnel to fill up burette 4) Open tap to fill to mark with no bubbles |
| Step 2 for titration | Prepare pipette and transfer standard solution |
| How to prepare a pipette | 1) Using a bulb, rinse pipette several times 2) Rinse with small volumes of standard solution 3) Fill with standard solution 4) Bottom of meniscus is on the marked line 5) Aliquot added to volumetric flask |
| Step 3 | Perform the titration |
| Performing the titration | 1) Add the indicator to the volumetric flask 2) Open tap slowly 3) Continue adding until a slight colour change occurs 4) Repeat 4 times (rough + 3 proper times) |
| Step 4 | Calculating the concentration of the unknown |
| How to do the calculation | 1) Write the balanced equation for the neutralisation reaction 2) Identify the mole coefficients in the balanced equation 3) Find the moles of known concentration 4) Multiple or divide by the mole coefficients to obtain the mole of the unknown 5) Use molarity formula to find the concentration |
| Titrant | The solution that is added from the burette |
| Aliquot | A known volume of a liquid |
| Titre | The volume of solution delivered from the burette that achieves an end point |
| End Point | The stage in a titration at which the indicator just changes colour |
| Suitable indicators for weak acid/strong base | Phenolphthalein |
| Suitable indicators for strong acid/strong base | Phenolphthalein Bromothymol Blue Methyl Orange |
| Suitable indicators for strong acid/weak base | Methyl Orange Bromothymol Blue |
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