3.2%
Объяснение:
dilute sulfuric acid reacts with zinc to produce hydrogen
zn + h2so4 = znso4 + h2
find the mass of gas released
n (h2) = n (zn) = m (zn) / mr (zn) = 13/65 = 0.2 mol
then the mass of hydrogen m (h2) = n * mr = 0.2 * 2 = 0.4 g
mass of solution at the end of the reaction
m (solution) = m (solution h2so4) + m (zn) - m (h2) = 1000 + 13-0.4 = 1012.6 gr
we put in a mass of zinc sulfate
n (znso4) = n (zn) = 0.2 mol
m (znso4) = n * mr = 0.2 * (65 + 32 + 64) = 32.2 gr
then the mass fraction of sulfate w = m (znso4) * 100% / m (solution) = 32.2 * 100 / 1012.6 = 3.2%
1)
HCL+NaOH=NaCL+H2O
H(+) + CL(-) + Na(+) + OH(-) =
Na(+) + CL(-) + H2O
H(+) + OH(-) =H2O
2)
CuSO4+2NaOH=Cu(OH)2+Na2SO4
Cu(2+) + SO4(2-) + 2Na(+) + 2OH(-) =
Cu(OH)2 + 2Na(+) + SO4(2-)
Cu(2+) + 2OH(-) = Cu(OH)2
3)
FeSO4+2NaOH=Fe(OH)2+Na2SO4
Fe(2+) + SO4(2-) + 2Na(+) + 2OH(-) =
Fe(OH)2 + 2Na(+) + SO4(2-)
Fe(2+) + 2OH(-) =Fe(OH)2
4)
FeSO4+Na2CO3=FeCO3+Na2SO4
Fe(2+) + SO4(2-) + 2Na(+) +CO3(2-) =
FeCO3 + 2Na(+) + SO4(2-)
Fe(2+) + CO3(2-) = FeCO3
Здесь явная ошибка: выделиться 2,8 литр H2 а не 28 л
2HCOH+2Na=2HCONa+H2
m(HCOH)=60*2,8/22,4=7,5г
CH3COH+Ag2O=CH3COOH+2Ag
m(CH3COH)=44*86,4/216=17,6г
56,8-(17,6+7,5)=31,7 г вода
w (hcoh)=7,5*100/56,8=13,2042%
w (ch3coh)=30,9859%
Ответ:
Объяснение:
4Ca + 10HNO3 = 4Ca(NO3)2 + N2O + 5H2O
Ca(0) -2e = Ca(+2) 4 ок-ие
в-ль
2N(+5) +8e = 2N(+) 1 в-ие
ок-ль
4Ca + 9HNO3 = 4Ca(NO3)2 + NH3 + 3H2O
Ca(0) -2e = Ca(+2) 4 ок-ие
в-ль
N(+5) +8e = N(-3) 1 в-ие
ок-ль