The mass percent of "NaCl"NaCl is 75 %. Its mole percent is 79.3 mole %.
The formula for mass percent is
color(blue)(|bar(ul(color(white)(a/a)"Mass percent" = "mass of component"/"total mass" × 100 %color(white)(a/a)|)))" "
"Total mass" = "600 kg + 200 kg" = "800 kg"
∴ "Mass % of NaCl" = (600 color(red)(cancel(color(black)("g"))))/(800 color(red)(cancel(color(black)("g")))) × 100 % = "75 % (m/m) NaCl"
The formula for mole percent is
color(blue)(|bar(ul(color(white)(a/a)"Mole percent" = "moles of component"/"total moles" × 100 %color(white)(a/a)|)))" "
"Moles of NaCl" = 600 color(red)(cancel(color(black)("kg NaCl"))) × "1 kmol NaCl"/(58.44 color(red)(cancel(color(black)("kg NaCl")))) = "10.27 kmol NaCl"
"Moles of KCl" = 200 color(red)(cancel(color(black)("kg KCl"))) × "1 kmol KCl"/(74.55 color(red)(cancel(color(black)("kg KCl")))) = "2.683 kmol KCl"
"Total moles = 10.27 kmol + 2.683 kmol = 12.95 kmol"
∴ "Mole percent of NaCl" = (10.27 color(red)(cancel(color(black)("kmol"))))/(12.95 color(red)(cancel(color(black)("kmol")))) × 100 % = "79.3 mole %"
