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C3 - End of Topic - Coggle Diagram
C3 - End of Topic
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L6 - Atom Economy
The higher the atom economy, the less waste is produced through a reaction.
Atom economy = (Relative formula mass of desired products / Relative formula mass of all reactants) x 100
Processes with high atom economies are much more efficient, rendering the reaction sustainable with low wastage produced.
Industries prefer processes with a high atom economy as this aids in sustainable development (conserving natural resources).
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L5 - Percentage Yield
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Many factors may contribute to a yield that is < 100:
- The reaction may be reversible (does not go to completion)
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- Some of the reactants may have been left in the apparatus or spilt
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- Undesirable side-reactions may have taken place
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- Reactants may not be pure
In industry, it is important that a manufacturer ensures that a reaction has the highest possible percentage yield as this renders the production more efficient, with less waste produced. This allows for maximum profit to be made. This also means that there is typically a lower consumer cost.
L7 - Concentration
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To convert cm^3 to dm^3, you must divide by 1000
The concentration of a solution is how much of a solvent had dissolved in a certain amount of a solute. The more solute dissolved in a given volume of a solvent, the higher the concentration.
L8 & L9 - Titrations
Method: (adding alkali to aicd):
- First, measure 25.0cm^3 of acid with a volumetric pipette, this should be drawn up with a pipette filler and should be measured as 25.0cm^3 at the bottom of the meniscus.
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- Next, a phenolphthalein indicator should be added to the fixed acid volume and a white tile should be placed under the conical flask containing the acid.
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- Use a burette to contain a volume of alkali. The initial volume of this alkali should be recorded.
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- The alkali should slowly be added to the acid in the conical flask, when an end point is being reached the alkali should be added drop-wise, gently shaking the flask after every drop.
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- When a colour change from colourless to slight pink is observed. The volume of alkali that is still in the burette should be recorded. We can then calculate the volume of alkali used.
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- These steps must be repeated until the titres recorded are concordant (within 0.1 cm^3 of eachother).
H+ ions are contained within all acids, OH- ions are contained within all alkalis.
IMPORTANT: Before the titration begins, the equipment used should be washed with distilled water to avoid any contamination (which may cause inaccuracy with results) and then the equipment should be rinsed with the solution you are using to stabilise the pH.
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L3 - Mass Changes
Uncertainty is expressed as " + or - half of the smallest scale division. Uncertainty on a thermometer that measures in 1 degree Celsius increments would have an uncertainty of + or - 0.5 from the measured value.
Alternatively, uncertainty is + or - half the range of data.