PAPER 1 Flashcards
define enthalpy change of reaction
the enthalpy change when the number of moles of reactants as specified in the balanced equation react together
define enthalpy change of neutralisation
the enthalpy change when solutions of an acid and an alkali react together under standard conditions to produce 1 mole of water
what does Hess’ law state
Hess’s law states that total enthalpy change for a reaction is independent of the route by which the chemical change takes place
what can you observe when water reacts with a group 2 metal
- fizzing
- temp of solution increasing
- metal dissolving
what does group two metal and oxygen make
metal oxide MO
whta does a group 2 metal and water make
metal hydroxide
M(OH)2
what happens to solubility of g2 metalhydroxide down the group
it increases down the group
so pH gets higher
what do the 4 halogens look like at rtp
flourine: pale yellow gas
chlorine: green gas
bromine: reddish liquid
iodine: shiny grey solid
what are the colour of solutions with the different halogens free
chlorine: pale green (often colourless)
bromine: orange
iodine: brown
what are the colour of solutions with the different halogens free WITH ORGANIC SOLVENT
(cyclohexane)
chlorine:colourless
bromine:orange
iodine: purple
equation for reaction of COLD NaOH and chlorine
what is bleach
NaClO
what is disproporionation reaction w HOT NaOH and chlorine
MAKES SODIUMCHLORATE 5 INSTEAD ON 1(for cold)
what is the formula linking half life and rate constant
half life = Ln(2)/k
suggest how to reduce percentage uncertainty
- increase ur measurement e.g. measure a larger volume or mass
- use smaller unit measurment e.g. mass balance to 3.d.p
