C2.3 How much? Flashcards
What is the relative mass of a proton
1
What is the relative mass of a neutron
1
What is the relative mass of an electron
n/a - negligible mass
What is a mole?
the relative atomic mass of an element in grams
What is the atomic number?
the number of protons
What is the mass number?
The number of protons and neutrons
What are isotopes?
The same element (same proton number) but different number of neutrons
How do you work out a relative formula mass (Mr) of a compound?
add up all the masses of the elements in it in the ratio shown by its formula
How do you work out the percentage of an element in a compound?
(The mass of element / total mass of compound) x 100
What is the equation to work out number of moles?
No. of mols = mass/relative formula mass
What should you always do to an equation?
BALANCE IT
What is percentage yield?
(actual yield/predicted yield) x100
What is atom economy and the equation to calculate it?
making as much useful product as possible
% atom economy = (mass of useful products/mass of all products) x100
Why is it important to maximise percentage yield and minimise energy?
to conserve earth’s limited resources and reduce pollution also money loss
What is a reversible reaction and the symbol for it?
The products can react to make the original reactants again
What happens after we add just reactants to a reversible reaction?
will never produce 100% products
some will turn back into reactants, when this is all at the same rate you reach dynamic equilibrium
How do we identify additives?
paper chromatography
Why are additives added to food?
to improve appearance, taste, shelf life
What are modern instrumental instrumental methods of analysis?
gas chromatography and mass spectrometry
What is gas chromatography?
separates compounds in a mixture, a carrier gas moves vapour through a column and condense at different rates
What is mass spectrometry?
can identify substances quickly and accurately can detect small amounts and provide Ar for gas chromatography through (molecular ion) peaks that show amounts of different substances
What is good about modern instrumental methods?
fast, accurate, sensitive
