Quantitative Chem Flashcards
(12 cards)
Where is Ar - relative atomic mass found on periodic table
The mass number
How to find Mr - relative formula mass
Add up all the Ar’s of the formula
How to calculate % mass of an element in a compounds
Percentage mass of an element in a compound = At x number of atoms of that element / Mr of the compound
How to find mass (g)
Mr mole
Avogadro constant
6.02x10^23
Symbol for the unit mole
mol.
How many grams is 1 tonne
1000000 1 mil
How many grams is 1mg
0.001g
Conservation of mass law
In a reaction, the total mass of the reactants must equal the total mass of the products
Must the Mr of both sides of equation be the same
Yes
Why might it appear that the mass changed over the reaction
If the mass increase it’s because one of the reactant is a gas that’s found in air such as oxygen and the products are solids liquids or aqueous for example oxygen might form a metal oxide when the metal reacts with air. If mass decreases it’s because one of the products is a gas so the gas might escape if the vessel isn’t enclosed
Do u include big number in front of element in Mr such as 2Ca
No but do small number after it
