Amount Of Substance Flashcards
What is a mole?
6.02 x10^23 things
What does one mol of carbon-12 atoms weigh?
12 grams
What is Avogadro’s constant?
The value 6.02 x 10^23
So number of particles = number of moles x Avogadro’s constant
How can you calculate moles
Mass/mr
Or
Conc x vol
How can you work out density
Mass/volume
What is the empirical formula?
The simplest whole number ratio of the atoms in a molecule
How do you calculate water of crystallisation?
If you are given the percentage mass that are water molecules, you can work out the mass and use the equation moles = mass/mr.
You can then figure out the moles of the compound. Finally divide the moles of water by the moles of the compound to give the number of H2O molecules
What are hydrated salts?
Salts with water molecules within their structure
What does diprotic mean?
It gives up two protons per molecule in solution
What is Avogadro’s law?
At the same temperature and pressure, one mole of two gases will be the same volume
What is the equation for number of moles of gas?
Volume of gas(dm3) / 24
This is only true if the gas is at room temperature and pressure
What do coefficients represent?
The ratio of the amount of each substance in the reaction
What is the ideal gas equation?
Pressure (Pa) x volume (m^3) = number of moles x gas constant(8.314) x temperature (k)
What 5 factors cause deviation from 100% percentage yield?
- Hydration of your products
- Side reactions, creating undesired products
- incomplete reactions, for reversible or slow
- extraction, difficulty separating the product from the reaction mixture
- waste, woke chemicals remain stuck to the glassware
How can you work out the percentage yield?
Real yield / theoretical yield x 100
