Hi there! If you can help me with these Grade 11 Chemistry questions, that would be fantastic!
The molar mass of all the salts are obtained by adding up individual atomic masses of its constituent atoms.
Thus, molar masses of the salts of potassium are:
KCl : (39.01+35.45), i.e. 74.46 g/mol
K2SO4: (2*39.01+32.06+4*16), i.e. 174.08 g/mol
K2O: (2*39.01+16)=94.02 g/mol
1 kg of KCl is 1000/74.46, i.e 13.43003 moles.
From the formula of the salts it is evident that,
1 mole (or atom) of potassium is contained in: 1 mole of KCl,
: 1/2 mole of K2SO4
: 1/2 mole of K2O
Therefore, 13.43003 moles (or atoms) of potassium is contained in: 13.43003 moles of KCl,
: 13.43003/2 moles of K2SO4, or 13.43003/2*174.08, i.e. 1.16895 kg of K2SO4
: 13.43003/2 moles of K2O or, 13.43003/2*94.02, i.e. 0.6313457 kg of K2O
a. To supply the same amount of potassium as 1 kg KCl, on a per dollar basis,
1.16895 kg of K2SO4 should cost $0.55
1.00 kg of K2SO4 should cost $0.55/1.16895, i.e. $0.4705 `~~$0.47` .
b. Mass (in Kg) of K2O that contains the same number of moles of K atoms as 1.00 kg of KCl is 0.6313457 kg `~~0.63 ` kg.