①配制0.5mol/L NaOH溶液50mL
m(NaOH)=cV*M=0.5*50*10^-3*40=1(g)
②配制0.1mol/L CuSO4溶液500mL
n(CuSO4·5H2O)=n(CuSO4)=cV=0.1*500*10^-3=0.05(mol)
m(CuSO4·5H2O)=n(CuSO4·5H2O)*M=0.05*250=12.5(g)
③配制0.2mol/L H2SO4溶液500mL
m(H2SO4)=cV*M=0.2*500*10^-3*98=9.8(g)
设需98%的浓H2SO4 V mL
ρV*98%=m(H2SO4)
V=m(H2SO4)/(ρ*98%)=9.8/(1.84*98%)=5.4(mL)配制250ml1mol/LHCL溶液，需要12mol/LHCL溶液的体积是？c1*V1=c2*V2V2=c1*V1/c2=250*1/12=20.8(mL)