Formulas Flashcards
1 mole of Carbon contains ___ atoms.
6.02x10^23
1 mole of water contains ____ molecules.
6.02x10^23
How do you calculate the number of moles?
Number of moles= Number of particles/6.02x10^23
How do you calculate the number of moles using molar mass?
Number of moles=Mass(g)/Molar mass (g/mol)
n=m/M
How to calculate the empirical formula of a Compound? (4)
- Write down the mass of each element
- Write down the molar mass of each element
- Divide each mass by its molar mass to obtain the number of moles
- Divide each number of moles by the smallest number of moles
How to calculate the empirical formula from percentage composition?
Make the percentage out of 100g in order to simply the ratios.
Empirical Formula to Molecular Formula? (4)
- Make the ratio in terms of x
- Multiply the RAM by the ratios
- Solve for x
- Multiply the OG algebraic ratios by the new value of x
What is Avogadro’s Law?
Equal volumes of gases, at the same temperature and pressure, contain an equal number of particles or molecules.
How much volume does 1 mole of gas occupy at STP?
22.4 dm^3
How do you calculate the number of moles of a gas?
Number of moles of a gas=Volume of a gas/Molar volume of a gas
n=V/Vm
How do you calculate the concentration when you have the mass?
Concentration=Mass (g)/Volume of solution (dm^3)
c=n/v
How do you calculate the concentration when you have the number of moles?
Concentration=Number of moles (mol)/Volume of solution (dm^3)
Bonus: How do you calculate the amount of solute?
Number of moles of solute=Concentration (mol/dm^3) x Volume of solution (dm^3)
For acids and bases, the equivalent weight of a compound is that weight of the compound that can supply 1 mole of H+ or -OH ions
i.e. equivalent weight =
equivalent weight = molar mass in g/ no of H+ or -OH per mole
In medical practice, equivalent weight is often used to denote the combining power of ions.
eg. equivalent weight of an ion =
equivalent weight of an ion = molar mass in g / ionic charge
