Calculations Involving Masses Flashcards
What is the relative formula mass of a compound?
The relative atomic mass of all the atoms added together
How do you find the relative formula mass?
Use the periodic table to find the relative atomic masses of the elements in the compound.
Add them all up to get the relative formula mass.
What is the empirical formula?
The simplest ratio of atoms
How do you find the empirical formula?
Get the numbers in the molecular formula.
Simplify the ratio by dividing them but the largest number that goes into them all.
That will then be the empirical formula when you put them back together.
How can you use Avogadro’s constant to calculate the number of particles?
Multiply Avogadro’s constant by the number of moles you have
How do you work out the number of moles in a given mass?
Number of moles = mass in grams / Relative mass or atomic mass
What can you use the empirical formula of a compound and its Mr to find out?
Molecular formula
What is a mole?
The amount of particles equal to a number called Avogadro’s constant: 6.02x10 to the power of 23
Why is Avogadro’s constant useful?
When you get that number of atoms or molecules of any element or compound, they weigh exactly the same number of grams as the relative atomic mass of the element or compound
What is concentration measured in?
Grams per dm cubed
How do you work out the concentration?
Make sure the mass is in grams.
Substitute the values into the formula.
What is the formula for concentration?
Concentration = mass of solute / volume of solution
