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Volumetric Analysis1
Volumetric Analysis: Acid/Base
Question | Answer |
---|---|
Branch of chemistry to which volumetric analysis belongs? | Quantitative Analysis |
Solute | A substance that will dissolve in a solvent |
Solvent | A solvent is a liquid in which a solute will dissolve. |
Solution | A solution is a perfect mixture of a solute and a solvent |
Concentration | The concentration of a solution is the amount of solute that is dissolved in a given amount of solvent |
Weight/weight | This is the amount of solute dissolved in 100g of water |
Weight/volume | This is the amount of solute dissolved in 100cm of water |
Volume/volume | This is the amount of solute mixed with 100cm of water |
Moles/Litre | A 1 molar solution is one that contains 1 mole of a substance in one litre of water. |
ppm | Parts per million. Also known as 1mg/litre |
Standard Solution | A standard solution is a solution of known concentration |
Primary Standard | A primary standard is a chemical used to make a standard solution. |
4 criteria of a a substance to be called a primary standard | 1: It must be available in a highly pure state 2: It must be stable in air. 3: It must dissolve readily in water 4: It should have a high molecular mass to allow for easy weighing and to minimise percentage error |
Why is Sulphuric Acid NOT considered a primary standard? | It absorbs moisture from the air |
Important steps when filling a volumetric flask? | 1: Rinsed with water. 2: Filled with a wash bottle to 1cm of the mark 3: Using a dropper at eye level fill the flask until the bottom of the meniscus sits on the line. 4: Stopper and invert 20 times. |
Why do we never pipette directly from the volumetric flask? | The pipette may contain some impurity that may contaminate the entire sample. We always pour some of the solution into a beaker before pipetting. |
Important steps when using a pipette? | 1: Never pipette by mouth, always use a pipette filler 2: Rinse with water, then the solution it will contain. 3: Fill the pipette until the bottom of the meniscus sits on the line. 4: Do not blow out the last drop, the pipette is calibrated for this. |
Important steps when using a burette? | 1: Clamp vertically in the retort stand. 2: Fill at eye level with a white tile/card behind the burette. 3: Using a funnel and then a dropper fill the burette until the bottom of the meniscus sits on the line. |
Why does the burette normally contain acid and not a base? | Bases can crystalise as they dry and clog the taps of burettes. For this reason the base is normally placed in the pipette. |
Why is a conical flask used instead of a beaker? | The conical flask allows the solution to be swirled without the risk of spilling. Beakers cannot allow this. |
Why is the conical flask placed on a white tile? | The white tile allows colour changes to be more easily seen. |
Hydrochloric Acid Vs Sodium Carbonate: Indicator and colour change? | Methyl Orange: Yellow to Pink |
Sodium Hydroxide Vs Hydrochloric Acid: Indicator and colour change? | Methyl Orange: Yellow to Red |
Sodium Hydroxide Vs Ethanoic Acid: Indicator and colour change? | Phenolphthalein. Colourless to pink. The base is placed in the burette and the acid in the concial flask. This is because it is easier to see a colourless to pink colour change than pink to colourless. |
Washing Soda (Sodium Carbonate Crystals) Vs Hydrochloric Acid: Indicator and colour change? | Methyl Orange: Yellow to Pink |
When using the volumetric analysis formula what is concentration calculated in? | The answer is always calculated in moles/Litre at the end as moles/Litre was used at the start! |