C5.1 Flashcards
WHAT AFFECTS percentage YIELD?
1) The reaction may not go to completion, for example in reversible reactions, not all of it reacts
2) the reaction may react differently, such as burning in the air lithium with oxygen for lithium oxide you might get lithium nitriere
3) some of the product may have been lost when TRANSFERING substances BETWEEN containers (for filtering purifying etc )
4)
Atom economy =
Considerations ? Why low atom economy bad
= sum of desired product / all of product x 100
INCLUDE MOLES in the addition
Atom economy:
Low means resources used up quickly, so may not be sustainable
- bad for environment as waste has to go somewhere
- low economies not efficient = nit profitable
So find a by product
Why do manufacturers chose a specific reaction
5 ways
Remmeber.
What happens if s by product is found
They need to consider the
- atom economy (efficient )
- percentage yield (reduce waste snd costs low)
- rate of reaction (fast )
- usefulness of by products (effiecnt)
- equilibrium position in equilibrium reactions
For example, if a by product is found, then that reaction pathways can be useful now as atom economy just gone up. If atom economy is 100% then it will be more efficient overall . Also like considerations like catalysts etc.
1 dm3 =
1 liter
1000cm3
Remember concentration =
G or mol / volume
How to do titrations
What are they?
Concordant titres?
How much volume
What decimal places / meniscus
What tile
Titration are methods in which you find the average volume of a concentration it takes to neutrals an acid or alkali.
1) add a known volume and concentration of acid to a CONICAL FLASK, using a volumetric Pipette (this is MORE ACCURATE, reduces systematic error). So like 25cm3, use Pipette filler for safety
2) add a few drops of a specific indicator that makes a distinct colour change , not universal. (PHENOLPHTHALEIN)
3) secure a Barette to a clamp stand, make sure it is vertical, and place a white tile underneath
4) with a funnel , add alkali and fill the Barette (50cm3). REMOVE AIR BUBBLE if there, by opening and closing tap and remove this excess.
5) take initial reading of the Burette, to 2 DECIMAL PLACES, reading at the bottom of the meniscus.
6) add 1ml of alkali each time, and SWIRL the contents to ensure they mixed, and record the reading of the pH. Keep doing this.
7) once the colour of the solution changes, stop. This is your end point. Record this
8)titre is end point - start point.
8) normally you do a test run to get a rough idea of where the tribe is. Then on your second go you can do it properly.
9) repeat it to get concordant titres = TWO RANGES WHICH ARE 0.1MC,3 OF EACH ITHER,
THENcalculate A MEAN, THIS WILL BE WITH HIGH PRECISION.
How to make a standard solution
1) dissolve 1 g of something in 150cm,3 water in beaker
2) add solution to a 250cm3 volumetric flask
3) add more water to reach the 250cm3 mark on the flask den
1 mole of any substance in the gas form occupies 24dm3 of volume at rtp and
Molar volume in General?
Therefore
Volume = mole x 24
v = 24M
REMEMBER RTP, one mole of gas of any substance only occupies 24 if at rtp , so volume = 24x mole
2) just like it is mole x molar volume (24)= volume just do that
Volume of a gas
1) fill measuring cylinder with water and while keeping its mouth underwater turn it upside down
2) clamp this cylinder
3) mix reactants in a conical flask, quickly attach a delivery tube
4) the volume of gas will be = to end reading- start
Mourn has to be down so any air can’t get in or out, or this affect results
