STOIKIOMETRI

Dengan menggunakan data massa atom (Ar)

Fe = 56

Na = 23

C = 12

Mg = 24

O = 16

S = 32

Tentukan Mr dari:

a. Fe₂O₃

b. MgSO₄

c. Na₂CO₃

d. C₃H₈O

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Mr = ∑ Ar = ∑ (Angka Indeks × Ar)

contoh : HₘIₙ ➡ m dan n adalah angka indeks

a ][

Fe₂O₃

Mr = ∑ Ar

Mr = 2 × Ar Fe + 3 × Ar O

Mr = 2 × 56 + 3 × 16

Mr = 160

b ][

MgSO₄

Mr = ∑ Ar

Mr = 1 × Ar Mg + 1 × Ar S + 4 × Ar O

Mr = 1 × 24 + 1 × 32 + 4 × 16

Mr = 120

c ][

Na₂CO₃

Mr = ∑ Ar

Mr = 2 × Ar Na + 1 × Ar C + 3 × Ar O

Mr = 2 × 23 + 1 × 12 + 3 × 16

Mr = 106

d ][

C₃H₈O

Mr = ∑ Ar

Mr = 3 × Ar C + 8 × Ar H + 1 × Ar O

Mr = 3 × 12 + 8 × 1 + 1 × 16

Mr = 60