Quantitative Chemistry Flashcards
what is the law of conservation of mass
no toms are lost or made during a chemical reaction so the mass of the products is the same as the mass of the reactants
in an ionic compound the charges on the ions have to ______ ___ to leave an overall charge of _____
in an ionic compound the charges on the ions have to cancel out to leave an overall charge of zero
are you allowed to change the small numbers on a molecule when balancing equations
no, you can never change the small numbers as this will result in a different molecule being made
what is realtive formula mass
the sum of the relative atomic masses of the atoms in the numbers shown in the formula
true or false Mr (relative formula mass) has no units
true
relative mass ______ involves big numbers
relative mass never involves big numbers
what does the percentage by mass tell us
what percentage of the mr is due to one of the elements in a compound
how do you calculate the percentage by mass of an element
total relative atomic mass of the atoms of that element
/
mr of the compound
x 100
how much is one mole
6.022 x 10^23
how do you work out the number of moles in an element
mass / ar
how do you work out the number of moles in an compound
mass / mr
how do you work out the mass
moles x mr
what is 1 mole also known as
avogrados constant
