c5.1 monitoring chemical reactions

Question 1

factors when determining a reaction pathway

Answer 1

yield 
atom economy 
usefulness
rate of the reaction 
equilibrium position

Question 2

rate of reaction and reaction time relationship

Answer 2

it is inversely proportional

1/ reaction time = rate of reaction.

Question 3

what affects the percentage yield

Answer 3

the reactant may react differently than expected
the reaction may not go to completion
you may lose some of the products when separating it from the reaction mixture to purify it

Question 4

atom economy

Answer 4

formula mass of desired product/ formula mass of all products * 100

Question 5

cm3 to dm3

Answer 5

divide by 1000

Question 6

titrations (6 marker)

Answer 6

• put a known volume of alkali into a conical flask
• add a few drops of indicator
• then add acid using a burette, until the indicator changes colour.
• repeat the experiment using the known volume of acid until you get at least 2 concordant titres

Question 7

what colour is phenolphthaelin in acid and alkali

Answer 7

acid- colourless

alkali- pink

Question 8

how can you make a titration more accurate

Answer 8

• use a volumetric pipette to measure the volume of alkali
• use a burette for the acid
• the burette should be clamped vertically
• swirl the flask
• keep a white tile underneath to see any colour change
• your first titre is usually a rough run so ignore it

Question 9

safety for a titration

Answer 9

wear eye protection and gloves too

make sure the clamps are put on correctly and cant fall off

Question 10

what is molar volume

Answer 10

one mole of substance in the gas state occupies the same amount of volume at the same temperature and pressure. for a gas it is :
24 dm3/mol

Question 11

volume of a gas equation

Answer 11

volume (dm3) = amount in mol * 24 dm3/mol