Ответ:

дано

m(ppa Pb(NO3)2) = 300 g

W(Pb(NO3)2) = 15%

m(ppa NaOH) = 100 g

W(NaOH) = 30%

------------------------------

m(Pb(OH)2)-?

m(Pb(NO3)2) = 300 * 15% / 100% = 45 g

M(Pb(NO3)2) = 331 g/mol

n(Pb(NO3)2)  = m/M = 45 / 331 = 0.136 mol

m(NaOH) = 100 * 30% / 100% = 30 g

M(NaOH) = 40 g/mol

n(NaOH) = m/M = 30 / 40 = 0.75 mol

n(Pb(NO3)2) < n(NaOH)

Pb(NO3)2+2NaOH-->Pb(OH)2↓+2NaNO3

M(Pb(OH)2) = 241 g/mol

n(Pb(NO3)2)  = n(Pb(OH)2) = 0.136 mol

m((Pb(OH)2) = n*M = 0.136 * 241 = 32.776 g

ответ 32.776 г

Объяснение: