Dengan menggunakan massa atom relatif(Ar) pada tabel periodik unsur(untuk memudahkan hitungan gunakan bilangan bulat saja),Hitunglah massa molekul relatif(Mr) z

Jawab :

Dengan menggunakan massa atom relatif (Ar) pada tabel periodik unsur. Nilai massa molekul relatif (Mr) zat-zat berikut. :

a. NaOH

Mr NaOH  = Ar Na + Ar O + Ar H

                = 23 g/mol + 16 g/mol + 1 g/mol

                = 40 g/mol

b. HNO₃

Mr HNO₃  = Ar H +  Ar N + (3 × Ar O)

               = 1 g/mol + 14 g/mol + (3 × 16 g/mol)

               = 1 g/mol + 14 g/mol + 48 g/mol

               = 63 g/mol

c. NaNO₃

Mr NaNO₃  = Ar Na + Ar N + (3 × Ar O)

                 = 23 g/mol + 14 g/mol + (3 × 16 g/mol)

                 = 23 g/mol + 14 g/mol + 48 g/mol

                 = 85 g/mol

d. CH₄

Mr CH₄  = Ar C + (4 × Ar H)

            = 12 g/mol + (4 × 1 g/mol)

            = 12 g/mol + 4 g/mol

            = 16 g/mol

e. Ca₃(PO₄)₂

Mr Ca₃(PO₄)₂  = (3 × Ar Ca) + (2 × Ar P) + (8 × Ar O)

                      = (3 × 40 g/mol) + (2 × 31 g/mol) + (8 × 16 g/mol)

                      = 120 g/mol + 62 g/mol + 128 g/mol

                      = 310 g/mol

f. MgSO₄

Mr MgSO₄ = Ar Mg + Ar S + (4 × Ar O)

                  = 24 g/mol + 32 g/mol + (4 × 16 g/mol)

                  = 24 g/mol + 32 g/mol + 64 g/mol

                  = 120 g/mol

g. Na₂HPO₄

Mr Na₂HPO₄  = (2 × Ar Na) + Ar H + Ar P + (4 × Ar O)

                     = (2 × 23 g/mol) + 1 g/mol + 31 g/mol + (4 × 16 g/mol)

                     = 46 g/mol + 1 g/mol + 31 g/mol + 64 g/mol

                     = 142 g/mol

h. Fe₂(SO₄)₃

Mr Fe₂(SO₄)₃  = (2 × Ar Fe) + (3 × Ar S) + (12 × Ar O)

                      = (2 × 56 g/mol ) + (3 × 32 g/mol) + (12 × 16 g/mol)

                      = 112 g/mol + 96 g//mol + 72 g/mol

                      = 280 g/mol

i. C₁₂H₂₂O₁₁

Mr C₁₂H₂₂O₁₁  = (12 × Ar C) + (22 × Ar H) + (11 × Ar O)

                     = (12 × 12 g/mol) + (22 × 1 g/mol) + (11 × 16 g/mol)

                     = 144 g/mol + 22 g/mol + 176 g/mol

                     = 342 g/mol

j. H₂C₂O₄

Mr H₂C₂O₄ = (2 × Ar H) + (2 × Ar C) + (4 × Ar O)

                  = (2 × 1 g/mol) + (2 × 12 g/mol) + (4 × 16 g/mol)

                  = 2 g/mol + 24 g/mol + 64 g/mol

                  = 90 g/mol

k. CO(NH₂)₂

Mr CO(NH₂)₂  = Ar C + Ar O + (2 × Ar N) + (4 × Ar H)

                      = 12 g/mol + 16 g/mol + (2 × 14 g/mol) + (4 × 1 g/mol)

                      = 12 g/mol + 16 g/mol + 28 g/mol + 4 g/mol

                      = 60 g/mol

l. C₂H₅OH

Mr C₂H₅OH  = (2 × Ar C) + (6 × Ar H) + Ar O

                    = (2 × 12 g/mol) + (6 × 1 g/mol) + 16 g/mol

                    = 24 g/mol + 6 g/mol + 16 g/mol

                    = 46 g/mol

m. CuSO₄.5H₂O

Mr CuSO₄.5H₂O  = Ar Cu + Ar S + (9 × Ar O) + (10 × Ar H)

                            = 63,5 g/mol + 32 g/mol + (9 × 16 g/mol) + (10 × 1 g/mol)

                            = 63,5 g/mol + 32 g/mol + 144 g/mol + 10 g/mol

                            = 249,5 g/mol

n. MgSO₄.7H₂O

Mr MgSO₄.7H₂O  = Ar Mg + Ar S + (11 × Ar O) + (14 × Ar H)

                            = 24 g/mol + 32 g/mol + (11 × 16 g/mol) + (14 × 1 g/mol)

                            = 24 g/mol + 32 g/mol + 176 g/mol + 1 g/mol

                            = 233 g/mol

Note : 2 soal lagi cara perhitungannya sama.

Pelajari lebih lanjut :

Materi tentang contoh soal massa molekul relatif (Mr) https://brainly.co.id/tugas/21160741

Materi tentang contoh soal massa molekul relatif (Mr) https://brainly.co.id/tugas/10368157

Materi tentang contoh soal massa molekul relatif (Mr) https://brainly.co.id/tugas/19003966

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Detail Jawaban :

Kelas : 10

Mapel : Kimia

Bab : 9

Kode : 10.7.9

Kata Kunci : mol, Ar, bilangan avogadro