Matters and combining matters
why do atoms form bonds?
to get a stable electronic structure
chemical name of NaNO2
sodium nitrite
Name factors that affect the rate of a typical reaction
temperature, pressure, concentration, surface area, catalyst
Name 3 alkali metals
lithium, sodium, potassium, rubidium, caesium
Give general formula for ethanol homologous series
CnH2n+2O/CnH2n+1OH
The gas with the fastest rate of diffusion
hydrogen
Define 'the mole'
the amount of particles equal to the the number of particles in 12g of carbon-12
Define 'catalyst'
a substance that can speed up the reaction without being changed itself after the reaction
2 main steps in water treatment process
filtration and chlorination
describe 3 natural polymers
cellulose, starch, protein
electron configuration of manganese(Z=25)
(the maximum electrons on each shell is 2, 8, 8(18), 2(8)(18) respectively)
2, 8, 13, 2
Is chlorine reductant or oxidant in following reaction?
Cl2 + NaOH -> NaCl + NaClO + H2O
both
the type of oxide that can dissolve in both acid and alkali solution
amphoteric
describe a 2-substance mixture that can supply all 3 necessary elements for plants
E.g KNO3 + (NH4)3PO4
Why does petroleum have to be refined?
separate it into fractions that we can use
why should we close the chromatography chamber by a lid?
- prevent solvent from evaporating from the fluid and the paper
what is 'brine'?
concentrated solution of sodium chlorine
suggest 2 suitable chemicals to prepare copper(II) sulfate
CuO/Cu(OH)2/CuCO3 + H2SO4
predict the color and physical state of astatine (the 5th element of group 7)
black solid
Give the conditions for hydration reaction of ethene
570 degree, 60-70 atm, phosphoric acid
why can graphite conduct electricity?
each carbon atom has 1 free electron that can move freely to carry electricity
Find the oxidation state of Cr in K2Cr2O7
+6
Compare the energy levels between reactants and products in an exothermic reaction
energy of reactants > energy of products
why is lime kiln always kept open?
why buring ethanol does not contribute to global warming?
ethanol is made from plants, the carbon dioxide emitted can then be absorbed again by plants