Calculate the number of moles of sulfur in 57.1 g of sulfur. Note that molar mass of sulfur is 32.06 g/mol
2 answers
57.1g * 1mole/32.06g = 57.1/32.06 moles
Not to be nit picky (I REALLY don't want to be nit picky) but some would argue that sulfur is S8 and the molar mass is 32.06*8 or 256.48. Frankly, although I agree sulfur actually is S8, I think that just complicates stoichiometry problems because it makes equations 8 times larger than they would otherwise be AND it doesn't change the end product. For example, burning sulfur in oxygen. Instead of the equation being
S + O2 ==> SO2 and 32.06 g S forming 64.06 g SO2 you get
S8 + 16O2 ==> 8SO2
32.06/256.48 = 0.125 mols S
0.125 moles S x (8 moles SO2/1 mol S8) = 1 mol SO2.
1 mol SO2 x 64.06 g/mol = 64.06 g SO2 formed. Same answer but MUCH more work to get there. This is just a nice way of reminding students that H2, N2, O2, F2, Cl2, Br2 and I2 are diatomic gaseous element while S exists as S8 and P exists as P4.
There is a mnemonic for that.
H-N-O-F-Cl-Br-I
Have No Fear Of Ice Cold Beer and their twins S8 and P4
Just a little extra information for those interested.
S + O2 ==> SO2 and 32.06 g S forming 64.06 g SO2 you get
S8 + 16O2 ==> 8SO2
32.06/256.48 = 0.125 mols S
0.125 moles S x (8 moles SO2/1 mol S8) = 1 mol SO2.
1 mol SO2 x 64.06 g/mol = 64.06 g SO2 formed. Same answer but MUCH more work to get there. This is just a nice way of reminding students that H2, N2, O2, F2, Cl2, Br2 and I2 are diatomic gaseous element while S exists as S8 and P exists as P4.
There is a mnemonic for that.
H-N-O-F-Cl-Br-I
Have No Fear Of Ice Cold Beer and their twins S8 and P4
Just a little extra information for those interested.
2 answers