2018 paper 1 Flashcards
(13 cards)
Describe a method to make pure, dry crystals of magnesium sulfate from a metal oxide and a dilute acid [6]
-use mgo and sulfuric acid
-add sulfuric acid to beaker
-warm it
-add mgo
-stir
-continue adding until in excess
-filter
-using a filter paper and funnel
-to remove excess mgo
-heat solution in an evaporating basin
-to crystallisation point
-leave to crystallise
-pat dry with filter paper
formula for number of moles of gas
moles = vol/24
Guve one reason why it would be hazardous if water came into contact with sodium
violent reaction
more concentrated acids
have lots of acid in a small volume of water
less concentrated acids
have little acid in a large volume of water
strong acids
weak acids
are completely ionised in solution
are partially ionised in solution
formula for atom economy
Mr of useful/Mr of all products
what is avogadros constant
6.02 x23 atoms in one mole
one mole has the same mass as the Mr of the substance
list uses of nanoparticles
healthcare
electronics
cosmetics
catalysts
Explain why in titration you shoudl use a pipette to measure the dilute sulfuric acid and a burette to measure the sodium hydroxide solution
-pipette measures fixed volume
advantages of hydrogen fuel cells
disadvantages too
advantages:
-the only waste is water
-do not need to be electricslly charged
-do not grt let efficient the longer they run
(can be a source of drinking water in space)
disadvantaged:
-hydrogen is highly flammable and difficult to store
-hydrogen is often produced from non-renewable resources
-produce relatively low pd so several are needed together
equations at positive &negative electrode of hydrogen fuel cells
overall equation
negative:
2H2 -> 4H+ + 4e-
positive:
O2 + 4H+ + 4e- -> 2H2O
overall:
2H2 + O2 -> 2H2O
guve 3 examples of weak acids
carbonic acids
ethanoic acids
citric acids
