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Diketahui massa atom relatif () unsur H = 1, C = 12, Na = 23, P = 31, S = 32, Ca = 40, dan Fe = 56. Hitung  senyawa-senyawa pada tabel berikut.

Pertanyaan

Diketahui massa atom relatif (begin mathsize 14px style italic A subscript r end style) unsur H = 1, C = 12, Na = 23, P = 31, S = 32, Ca = 40, dan Fe = 56. Hitung begin mathsize 14px style italic M subscript r end style senyawa-senyawa pada tabel berikut.
 

    

Pembahasan Soal:

Massa molekul relatif (begin mathsize 14px style M subscript r end style) merupakan jumlah total massa atom relatif (begin mathsize 14px style A subscript r end style) atom-atom penyusun suatu molekul. Penentuan begin mathsize 14px style M subscript r end style masing-masing senyawa sebagai berikut.

  • Senyawa begin mathsize 14px style H subscript 2 S O subscript 4 end style terdiri dari 2 atom H, 1 atom S, dan 4 atom O.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell M subscript r space H subscript 2 S O subscript 4 end cell equals cell 2 cross times A subscript r space H plus 1 cross times A subscript r space S plus 4 cross times A subscript r space O end cell row cell M subscript r space H subscript 2 S O subscript 4 end cell equals cell 2 cross times 1 plus 1 cross times 32 plus 4 cross times 16 end cell row cell M subscript r space H subscript 2 S O subscript 4 end cell equals cell 2 plus 32 plus 64 end cell row cell M subscript r space H subscript 2 S O subscript 4 end cell equals 98 end table end style 

  • Senyawa begin mathsize 14px style C H subscript 3 C O O H end style terdiri dari 2 atom C, 4 atom H, dan 2 atom O.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell M subscript r space C H subscript 3 C O O H end cell equals cell 2 cross times A subscript r space C plus 4 cross times A subscript r space H plus 2 cross times A subscript r space O end cell row cell M subscript r space C H subscript 3 C O O H end cell equals cell 2 cross times 12 plus 4 cross times 1 plus 2 cross times 16 end cell row cell M subscript r space C H subscript 3 C O O H end cell equals cell 24 plus 4 plus 32 end cell row cell M subscript r space C H subscript 3 C O O H end cell equals 60 end table end style 

  • Senyawa begin mathsize 14px style Ca subscript 3 open parentheses P O subscript 4 close parentheses subscript 2 end style terdiri dari 3 atom Ca, 2 atom P, dan 8 atom O.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell M subscript r space Ca subscript 3 open parentheses P O subscript 4 close parentheses subscript 2 end cell equals cell 3 cross times A subscript r space Ca plus 2 cross times A subscript r space P plus 8 cross times A subscript r space O end cell row cell M subscript r space Ca subscript 3 open parentheses P O subscript 4 close parentheses subscript 2 end cell equals cell 3 cross times 40 plus 2 cross times 31 plus 8 cross times 16 end cell row cell M subscript r space Ca subscript 3 open parentheses P O subscript 4 close parentheses subscript 2 end cell equals cell 120 plus 62 plus 128 end cell row cell M subscript r space Ca subscript 3 open parentheses P O subscript 4 close parentheses subscript 2 end cell equals 310 end table end style  

  • Senyawa begin mathsize 14px style Fe subscript 2 open parentheses S O subscript 4 close parentheses subscript 3 end style terdiri dari 2 atom Fe, 3 atom S, dan 12 atom O.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell M subscript r space Fe subscript 2 open parentheses S O subscript 4 close parentheses subscript 3 end cell equals cell 2 cross times A subscript r space Fe plus 3 cross times A subscript r space S plus 12 cross times A subscript r space O end cell row cell M subscript r space Fe subscript 2 open parentheses S O subscript 4 close parentheses subscript 3 end cell equals cell 2 cross times 56 plus 3 cross times 32 plus 12 cross times 16 end cell row cell M subscript r space Fe subscript 2 open parentheses S O subscript 4 close parentheses subscript 3 end cell equals cell 112 plus 96 plus 192 end cell row cell M subscript r space Fe subscript 2 open parentheses S O subscript 4 close parentheses subscript 3 end cell equals 400 end table end style 

  • Senyawa begin mathsize 14px style Na subscript 2 C O subscript 3 point 10 H subscript 2 O end style terdiri dari 2 atom Na, 1 atom C, 13 atom O, dan 20 atom H.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell M subscript r space end subscript Na subscript 2 C O subscript 3 point 10 H subscript 2 O end cell equals cell 2 cross times A subscript r space end subscript Na plus 1 cross times A subscript r space end subscript C plus 13 cross times A subscript r space end subscript O plus 14 cross times A subscript r space end subscript H end cell row cell M subscript r space end subscript Na subscript 2 C O subscript 3 point 10 H subscript 2 O end cell equals cell 2 cross times 23 plus 1 cross times 12 plus 13 cross times 16 plus 14 cross times 1 end cell row cell M subscript r space end subscript Na subscript 2 C O subscript 3 point 10 H subscript 2 O end cell equals cell 46 plus 12 plus 208 plus 14 end cell row cell M subscript r space end subscript Na subscript 2 C O subscript 3 point 10 H subscript 2 O end cell equals 280 end table end style 

Jadi, massa molekul relatif (begin mathsize 14px style M subscript r end style) masing-masing senyawa sebagai berikut.

  1. begin mathsize 14px style M subscript r space H subscript 2 S O subscript 4 equals 98 end style 
  2. begin mathsize 14px style M subscript r space end subscript C H subscript 3 C O O H equals 60 end style 
  3. begin mathsize 14px style M subscript r space Ca subscript 3 open parentheses P O subscript 4 close parentheses subscript 2 equals 310 end style
  4. begin mathsize 14px style M subscript r space Fe subscript 2 open parentheses S O subscript 4 close parentheses subscript 3 equals 400 end style 
  5. begin mathsize 14px style M subscript r space Na subscript 2 C O subscript 3 point 10 H subscript 2 O equals 280 end style 

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 15 Maret 2021

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