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C3 - Mocks - Coggle Diagram
C3 - Mocks
L6 - Atom Economy
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A reaction with only one reactant will have an atom economy of 100% because there are not waste products and the conservation of mass must hold.
High atom economy is desires to maintain sustainable development and to produce fewer waste products and conserve natural resources.
If less natural resources are used and fewer waste products are formed; the reaction is more economical (less money spent and greater profits).
L8 - Titrations 1
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A volumetric pipette is used to accurately measure a fixed volume of a solution; this is much more accurate than a measuring cylinder.
A burette is a glass tube used to precisely measure the volume of liquids (a burette has a tap as to allow for liquids to be added 'dropwise').
Points to consider during a titration:
- Carry the titration out more than once.
- Repeat until results are concordant (within 0.1cm^3).
- Discard anomalous results.
- Perform a rough titration to estimate an approximate an end point.
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L5 - Percentage Yield
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Chemical reactions may not have a 100% yield because:
- Some products may be lost during handling or in the apparatus.
- The reactants may not be pure (only one element or compound).
- Some side reactions may occur (unwanted products formed).
- The reaction may be reversible (as products form, they can re-form as reactants).
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L9 - Titrations 2
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Method (adding acid to alkali):
- Measure 25cm^3 of alkali with a volumetric pipette (measuring from the bottom of the meniscus). A pipette filler be used to draw up this quantity.
- Add a phenolphthalein indicator to the fixed volume of alkali (it should turn pink).
- Use a burette to hold a convenient, recorded volume of acid.
- Slowly add the acid to the alkali within the conical flask through the burette tap. The acid should be added dropwise when an end point is being reached.
- Continue to swirl the flask after every drop and when a colour change from pink to colourless is observed, record the new volume of acid in the burette.
Before the titration begins, all equipment should be rinsed with distilled water to avoid contamination and solutions of the same pH as the acid/alkali to stabilise the pH.
L4 - Limiting Reactants
If a reactant is limiting, it is completely used up in a reaction; it limits how much product can be produced. A reactant in excess will not be completely used up.
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