Question

Calculate the formula unit mass of
(Given : Atomic masses of Al = 27u, S = 32u, C = 12u, K = 39u, O = 16u, H = 1u, Ca = 40u) (i) Aluminium sulphate
(ii) Calcium oxide
(iii) Potassium carbonate

Answer 1

Answer:

i) 54u + 96u + 192u = 342u (Ans)

ii) 40u + 16u = 56u (Ans)

iii) (39x2)u + 12u + (16x3)u

= 78u + 12u + 48u

= 148u (Ans)

Answer 2

Answer:

i) 348 u

ii) 56 u

iii) 138 u

Explanation:

i) Aluminium Sulphate = Al2(SO4)3

Atomic mass of Al = 27 u

Atomic mass of S = 32 u

Atomic mass of O = 16 u

Formula unit mass = 2(27) + 3(32 + (4*16)) = 348 u

ii) Calcium Oxide = CaO

Atomic mass of Ca = 40 u

Atomic mass of O = 16 u

Formula unit mass = 40 + 16 = 56 u

iii) Potassium carbonate = K2CO3

Atomic mass of K = 39 u

Atomic mass of C = 12 u

Atomic mass of O = 16 u

Formula unit mass = 2(39) + 12 + 3(16) = 138 u

Just go for it :)