energetics
What is the term for a reaction that releases heat to the surroundings?
exothermic reaction
What type of bonding occurs between metals and non-metals?
ionic bonding
What colour does a lithium ion produce in a flame test
crimson red
What is the name of the negative electrode?
cathode
What is the general formula for alkanes?
CₙH₂ₙ₊₂
In an endothermic reaction, what happens to the temperature of the surroundings?
decreases
Why do ionic compounds conduct electricity when molten but not when solid?
because ions are free to move when molten
What is the test for sulfate ions and the results?
dd hydrochloric acid and barium chloride – a white precipitate forms
In electrolysis, where do oxidation reactions take place?
the anode
What type of bonds are present in alkanes?
single covalent bonds
Name the piece of equipment used to measure energy change in a reaction.
calorimeter
What structure do diamonds and graphite have in common?
giant covalent structure
What is the colour of the precipitate formed when sodium hydroxide is added to iron(III) ions?
brown
What is produced at the cathode when molten lead bromide is electrolysed?
lead
What is the name of the reaction where alkenes react with bromine water?
addition reaction
Combustion of fuels is an example of what type of reaction?
exothermic reaction
Why is graphite soft and slippery?
because the layers can slide over each other
How do you test for ammonium ions and the results?
add sodium hydroxide and warm – ammonia gas turns damp red litmus paper blue
What is the half-equation for the formation of oxygen during the electrolysis of water?
4OH⁻ → O₂ + 2H₂O + 4e⁻
What is formed when ethene reacts with steam in the presence of a phosphoric acid catalyst?
ethanol
A reaction has a bond energy input of 250 kJ and bond energy output of 500 kJ. What is the enthalpy change (∆H)?
-250 kJ (exothermic)
Explain why metals are malleable
because layers of positive ions can slide over each other
Which halide forms a yellow precipitate with silver nitrate?
iodide
In aqueous sodium chloride electrolysis, what gas is released at the anode?
chlorine
Explain how to distinguish between an alkane and an alkene using bromine water.
alkenes decolourise bromine water; alkanes do not