Alevel Chemistry HELP

How do you know the products of reactions?? everyone seems to just know and i feel abit silly pls help esp the exam questions that ask 'what do you observe' and 'write a equation'

Reply 1

Shush6295738

Original post by itsvarr

How do you know the products of reactions?? everyone seems to just know and i feel abit silly pls help esp the exam questions that ask 'what do you observe' and 'write a equation'

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Reply 2

TypicalNerd

Original post by itsvarr

How do you know the products of reactions?? everyone seems to just know and i feel abit silly pls help esp the exam questions that ask 'what do you observe' and 'write a equation'

Depends on what reaction you are conducting. You can learn a few general reactions from GCSE, for example:

H2O (l) + metal —> metal hydroxide + H2

H2O (g) + metal —> metal oxide + H2

Element + oxygen —> oxide

Element + halogen —> halide

Acid + metal —> salt + H2

Acid + metal oxide or hydroxide —> salt + H2O

Acid + metal carbonate —> salt + H2O + CO2

Hydrocarbon + excess O2 —> CO2 + H2O

Hydrocarbon + O2 (not in excess) —> mixture of C, CO, CO2 and H2O

Alkene + H2 —> alkane

For period 3, there are some more specific reactions to cover:

Nonmetal oxide + H2O —> acid (e.g SO3 + H2O —> H2SO4)

Nonmetal oxide + NaOH —> salt + H2O (e.g P4O10 + 12NaOH —> 4Na3PO4 + 6H2O, SiO2 + 2NaOH —> Na2SiO3 + H2O)

Amphoteric character of aluminium oxide and hydroxide:

Al2O3 + 6H^+ —> 2Al^3+ + 3H2O
Al2O3 + 2OH^- + 3H2O —> 2Al(OH)4^-

Al(OH)3(H2O)3 + 3H^+ —> Al^3+ + 6H2O
Al(OH)3(H2O)3 + OH^- —> Al(OH)4^- + 3H2O

(edited 1 year ago)

Reply 3

Kallisto

Entertainment Forum Helper

Original post by itsvarr

How do you know the products of reactions?? everyone seems to just know and i feel abit silly pls help esp the exam questions that ask 'what do you observe' and 'write a equation'

If you are able to recognize the class of materials the educts, it is easier to determine the products. Of course you need to know the products to them too. @TypicalNerd gave enough examples.

(edited 1 year ago)