A sample of sodium sulfate, Li2SO4, contains 6.78 x 10^23 formula units.
How many moles of Li2SO4 are there in the sample?
How many moles of Li+ ions are there in the sample?
You made a typo wring sodium sulfate but typing Li2SO4. I assume you meant Li2SO4.
1 mol contains 6.022E23 molecules so
6.78E23 molecules x (1 mol/6.022E23 molecules) = mols Li2SO4.
There are two Li^+ per 1 molecule Li2SO4; therefore, there must be twice mols Li&+ must 2x mols Li2SO4.
I don't understand where you are getting 6.022E23 from
That is a constant. It's just another unit like a dozen of something (12) or a gross of sometihig (144 or 12 dozen) or a ream (500 sheets paper). In this case there are 6.022E23 molecules in a mole of molecules, 6.022E23 atoms in a mole of atoms, 6.022E23 bananas in a mole of bananas, 6.022E23 cars in a mole of cars, 6.022E23 grains of sand in a mole of sand grains, etc. The reason you don't hear that much in everyday life is that the number is so huge that we don't come into contact with so many of one thing unless those things are extremely small (as in the case of atoms and molecules).
To find the number of moles of Li2SO4 in the sample, you can use Avogadro's number and the given number of formula units.
1. Find the molar mass of Li2SO4:
The molar mass of Li2SO4 is calculated by adding up the atomic masses of each element in the compound.
- Li: atomic mass = 6.94 g/mol (from the periodic table)
- S: atomic mass = 32.06 g/mol
- O: atomic mass = 16.00 g/mol
Molar mass of Li2SO4 = (2 * Li) + S + (4 * O) = (2 * 6.94) + 32.06 + (4 * 16.00) = 109.94 g/mol
2. Convert the given number of formula units to moles:
Given: 6.78 x 10^23 formula units
To convert formula units to moles, divide the given number by Avogadro's number (6.022 x 10^23 mol^-1) since one mole contains Avogadro's number of particles.
Number of moles of Li2SO4 = (6.78 x 10^23) / (6.022 x 10^23) = 1.13 moles
So, there are 1.13 moles of Li2SO4 in the sample.
To find the number of moles of Li+ ions, you need to know the ratio of Li+ ions to Li2SO4.
In Li2SO4, there are 2 moles of Li+ ions for every mole of Li2SO4.
3. Calculate the moles of Li+ ions:
Moles of Li+ ions = (Moles of Li2SO4) * (Ratio of Li+ ions / Li2SO4)
Moles of Li+ ions = (1.13 moles) * (2 moles Li+ ions / 1 mole Li2SO4) = 2.26 moles
So, there are 2.26 moles of Li+ ions in the sample.