1)Mr(HBr) = Ar(H) + Ar(Br) = 1 + 80 = 81
w (H/HBr) = Ar(H)/ Mr(HBr) x 100% = 1/81 х 100 = 1,23%
w (Br/HBr) = Ar(Br)/ Mr(HBr) x 100% = 80/81 х 100 = 98,77%
2) Mr(K2CO3) = 2Ar(K) + Ar(C) + 3Ar(O) = 2x39 + 12 + 3x16 = 138
w (2K/K2CO3) = 2Ar(K)/ Mr(K2CO3) x 100% = 78/138 х 100 = 56,52%
w (C/K2CO3) = Ar(C)/ Mr(K2CO3) x 100% = 12/138 х 100 = 8,69%
w (3О/ K2CO3) = 3Ar(О)/ Mr(K2CO3) x 100% = 48/138 х 100= 34,79%
3)Mr(Mg(OH)2) = 24 + 16x2 + 1x2 = 58
w (Mg/Mg(OH)2) = 24/ 58 х 100 = 41,38%
w (2O/Mg(OH)2) = 32/ 58 х 100 = 55,17%
w (2H/Mg(OH)2) = 2/ 58 х 100 = 3,45%
4)Mr(P2O5) = 2x31 + 5x16 = 142
w (2P/P2O5) = 2x31/ 142 х 100 = 43,66%
w (5O/P2O5) = 5x16/ 142 х 100 = 56,34% 5)Mr(feCl3) = 56 + 3 x 35,5 = 162,5 w (Fe/FeCl3) = 56/ 162,5 х 100 = 34,46% w (3Cl/FeCl3) = 3x35,5/ 162,5 х 100 = 65,54% 6)Mr(Cu(NO3)2) = 64 + 2x14 + 6x16 = 188 w (Cu/Cu(NO3)2) = 64/ 188 х 100 = 34,04% w (2N/ Cu(NO3)2) = 2x14/ 188 х 100 = 14,9% w (6O/Cu(NO3)2) = 96/ 188 х 100 = 51,06%
дано
m(H2SO4)=490g
m(MgO)=45g
найти
n(H2SO4)-?
n(MgO)-?
Решение
n(H2SO4=m(H2SO4) / M(H2SO4) , M(H2SO4)=98g/mol
n(H2SO4)=490/98 = 5 mol
n(MgO)=m(MgO) / M(MgO) , M(MgO)=40g/mol
n(MgO)=45/40=1.125 mol
ответ
n(H2SO4)=5 mol , n(MgO)=1.125 mol
2)
дано
n(ZnO)=3.5 mol
n(BaSO4)=0.025 mol
найти
m(ZnO)-?
m(BaSO4)-?
Решение
m(ZnO)=n(ZnO)*M(ZnO) , M(ZnO)=81g/mol
m(ZnO)=3.5*81=283.5 g
m(BaSO4)=n(BaSO4)*M(BaSO4) , M(BaSO4)=233 g/mol
m(BaSO4)=0.025*233= 5.825g
ответ
m(ZnO)=283.5g , m(BaSO4)=5.825g
3)
дано
m(Fe)=112g
найти
N(at)-?
Решение
N=(m/M)*N(A)*n ,
n - число атомов железа = 1. N(A)= 6.02*10^23 ,M(Fe)=56g/mol
N=(112/56)*6.02*10^23*1=1.2*10^24 атомов
ответ 1.2*10^24 атомов
4)
дано
n(N2)=0.6mol
m(H2)=10g
n(O2)=4.5 mol
найти
V(N2)-?
V(H2)-?
V(O2)-?
Решение
V(N2)=n(N2)*Vm = 0.6*22.4=13.44 L
V(H2)=(m(H2)*Vm) / M(H2) , M(H2)=1*2=2g/mol
V(H2)=10*22.4 / 2 = 112.5 L
V(O2)=n(O2)*Vm=4.5*22.4=100.8 L
ответ
V(N2)=13.44 L, V(H2)=112.5L , V(O2)=100.8L