explain why the alloy of copper and zinc is harder than pure copper Flashcards
Because the atoms in pure copper are of the same size which allows them to slide over eachother whereas the atoms in the alloy arent the same size and are distorted and cant slide over other atoms
why is excess copper carbonate used
to make sure all the acid has reacted with carbonate
describe how the student could produce copper sulfate crystals from the copper sulfate solution in beaker
heat it and leave it to cool for 24 hours untill crystal forms
why does the mass of the contents of the test tube decrease in mass when copper carbonate is thermally decomposed
carbon dioxide is produced which escapes
compare the structure and bonding of sodium chloride and oxygen
NaCl has a giant lattice structure
ionic bonding between metal and non metal
strong electrostatic force
oxygen is a simple covalent molecule
2 pairs of electrons are shared
what is meant by a strong acid
A strong acid is an acid that completely dissociates into its ions in water
what is meant by dilute aqueous solution
small no of h+ ions in a large volume
write the ionic equation for the reaction between an acid and an alkali
H+ (aq)+ OH− (aq)→H2O (l)
give twi improvements to the method to produce more accurate results
1) calc the average
2) improve the consistency of magnesium carbonate mass
Suggest the most economical method for extracting metal z
reduction with carbon
explain what happens to the positive carbon electrodes during the extraction of aluminium
positive electrode is made of carbon dioxide which escapes. so positive electrode has to be replaced
half eqn for the reaction at negative electrode
AL3+ + 3e- ——> Al
explain what happens to calcium atoms and to chlorine atoms when calcium reacts with chlorine to produce calcium chloride?
calcium atoms have 2 electrons on their outer shells where as both chlorine atoms have 7 electrons in their outer shell.
Chlorine atoms need 1 electron each to reach inert state whereas calcium atoms needs to remove 2 electrons.
therefore calcium atoms gains a +2 charge where as chlorine atoms get a -1 charge.
explain why chlorine is more reactive than bromine?
chlorine has fewer electrons shell
the electrons on the outer shell are closer to the nucleus
being closer to the nuclues, there is a stronger force of attarction and so easier to gain one electron
describe how the boiling points of the hydrogen halides change as the rlative formula mass increases
the boiling points initially decrease from hf to hci then increase from hci to hi. the unsually high boiling point of hf is die to hydrogen bonding
explain why carbon nanotubes can conduct electricity
delocalised electrons can carry a charge and move through the stricture
