Amount of Substance Flashcards
(32 cards)
Define relative atomic mass, Ar.
Average mass of on element of an atom / 1/12 mass of carbon-12
Define relative molecular mass, Mr.
Average mass of one molecule / 1/12 mass of carbon-12
How do you find relative molecular mass?
Add up all of the relative atomic masses.
What is Mr when referring to ionic compounds?
Relative formula mass.
What is a mole?
6.022 x 10^23 particles
Why is the Avagadro’s constant this number?
Number of atoms in 12g of carbon-12.
What is the molar mass?
Mass per mole of unit substance.
The relative atomic mass of any element in grams contains how many atoms?
1 mole.
number of moles = ?
Mass / Mr
What does a solution consist of?
A solvent with a solute dissolved in it.
What does the concentration of a solution tell us?
How much solute is present in a known volume of solution.
What is the equation for concentration in moldm^-3?
Number of moles / volume (dm^3)
How do you convert from cm^3 to dm^3?
x10-3
What is the ideal gas equation?
PV = nRT
What is P and what is it measured in?
Pressure, Pa.
What is V and what is it measured in?
Volume, m^3.
What is n and what is it measured in?
Number of moles, moles.
What is R and what is it and what is it measured in?
The ideal gas constant, 8.31 JK^-1mol^-1.
The same number of moles of any gas has the same what under the same pressure and temperature?
Volume.
Define empirical formula.
The formula that represents the simplest whole number ratio of the atoms of each element preset in the compound.
Give an example of an empirical formula.
CO2.
What is the first step in finding the empirical formula?
Find the masses of each element present in the compound.
What is the second step in finding the empirical formula of a compound?
Find moles, moles = mass/Mr.
What is the last step in finding the empirical formula of a compound?
Divide every value by the smallest number, use this as ratio.
