`#AkaShi`
PTHH:
`Na_2CO_3 + 2HCl -> 2NaCl + H_2O + CO_2↑`
`1 : 2 : 2 : 1 : 1`
`n_{HCl}=(136,875xx8%)/(36,5)=0,3 (mol)`
`⇒n_{Na_2CO_3}=1/2n_{HCl}=0,3xx1/2=0,15 (mol)`
`⇒m_{Na_2CO_3 pư}=0,15xx106=15,9 (g)`
`⇒m_{dd Na_2CO_3}=15,9:20%=(15,9xx100)/20=79,5 (g)`
b)
Theo tỉ lệ pt:
`n_{CO_2↑}=1/2n_{HCl}=0,3xx1/2=0,15 (mol)`
`⇒m_{CO_2↑}=nxxM=0,15xx44=6,6 (g)`
c)
Theo tỉ lệ pt:
`⇒n_{NaCl}=n_{HCl}=0,3 (mol)`
`⇒m_{NaCl}=nxxM=0,3xx58,5=17,55 (g)`
`⇒m_{dd sau pư}=m_{dd Na_2CO_3}+m_{dd HCl}-m_{CO_2↑}`
`⇒m_{dd sau pư}=79,5+136,875-6,6=209,775 (g)`
`⇒C%_{NaCl}=(17,55)/(209,775)xx100%≈8,37%`