Question

calculate the unit mass of Na2Co3 10 H2O

Answer 1

Hey there!

A correction in your question
" calculate the Formula unit mass of Na2Co3 10 H2O "

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Formula unit mass is the sum of atomic masses of all elements in a ionic compound

Na2Co3. 10 H2O ➡ Washing soda

Atomic weights:
Na=23
C=12
O=16
H=1
H2O=18 

Na2 = 46 
CO3 = 60 
10H2O = 180 
Formula Unit mass =23*2+2*6+3*16 +10(18)

=46+12+48+180

=106+180

=286

hope helped!