Chemical formulae, equations and calculations (Moles)
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what is the law of conservation of mass
no atoms can be lost or created so the total mass of reactants is always equal to the total mass of products
reactants are on which side of a word equation
the left
where are the products on a word equation
the right side
do you need to include the state symbols when making a symbol equation
yes
symbol for relative atomic mass
Ar
symbol for relative formula mass
Mr
how do you find Mr
add all the atomic masses of the molecules
what is a mole
the unit for the amount of substance
1 mol =
6.022 x 10²³
what is avogadros number
6.023 X 10²³ per mole
the mass of 1 mole of a substance is known as the
molar mass
the molar mass for an element is
the same as the relative atomic mass written in grams
for a compound, the molar mass is
the same as the relative molecular or formula mass in grams
moles = (equation)
MASS/Mr
why don’t you always get 100% yield in a chemical process (5)
Some reactants may be left behind in the equipment The reaction may be reversible and in these reactions a high yield is never possible as the products are continually turning back into the reactants Some products may also be lost during separation and purification stages such as filtration or distillation There may be side reactions occurring where a substance reacts with a gas in the air or an impurity in one of the reactants Products can also be lost during transfer from one container to another
The actual yield is the
recorded amount of product obtained
The theoretical yield is the
amount of product that would be obtained under perfect practical and chemical conditions
The percentage yield compares
the actual yield to the theoretical yield