Question

2) Determine a composição centesimal das espécies abaixo. ( H=1, C=12, N=14, O=16, Na=23, S=32 )
a) Ácido sulfúrico (H 2 SO 4 )
b) gás carbônico (CO 2 )
c) hidróxido de sódio (NaOH)
d) sacarose ( C 12 H 22 O 11 )

Answer 1

a)

$\mathsf{m_{H_{2}SO_4}}=2.1+32+4.16=98g/mol}$

$\mathsf{\%\,de\,H:\dfrac{2}{98}\times100\approx2,04\%}$

$\mathsf{\%\,de\,S:\dfrac{32}{98}\times100\approx32,65\%}$

$\mathsf{\%\,de\,O:\dfrac{64}{98}\times100\approx65,3\%}$

$\huge\boxed{\boxed{\mathsf{H_{2,04\%}S_{32,65\%}O_{65,3\%}}}}$

b)

$\mathsf{m_{CO_{2}}=1.12+2.16=44g/mol}$

$\mathsf{\%\,de\,C:\dfrac{12}{44}\times100\approx27,27\%}$

$\mathsf{\%\,de\,O:\dfrac{32}{44}\times100\approx72,72\%}$

$\huge\boxed{\boxed{\mathsf{C_{27,27\%}O_{72,72\%}}}}$

c)

$\mathsf{m_{NaOH}=23+16+1=40g/mol}$

$\mathsf{\%\,de\,Na:\dfrac{23}{40}\times100\approx57,5\%}$

$\mathsf{\%\,de\,O:\dfrac{16}{40}\times100=40\%}$

$\mathsf{\%\,de\,H:\dfrac{1}{40}\times100=2,5\%}$

$\huge\boxed{\boxed{\mathsf{Na_{57,5\%}O_{40\%}H_{2,5\%}}}}$