berapa massa nitrogen pada : a.) 25,2 gram NHO3 b.) 36 gram CO (NH2)2

(a)
Ar N = 14
Mr HNO3 = 63

[tex]massa N = \frac {1 \times Ar N}{Mr HNO_3} \times massa HNO_3[/tex]
[tex]massa N = \frac {1 \times 14}{63} \times 25,2[/tex]
massa N = 5,6 gram

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(b)
Ar N = 14
Mr Co(NH2)2 = 60

[tex]massa N = \frac {2 \times Ar N}{Mr CO(NH_{2})_2} \times massa CO(NH_{2})_2[/tex]
[tex]massa N = \frac {2 \times 14}{60} \times 36[/tex]
massa N = 16,8 gr