Answer in General Chemistry for Salem #279542
If ocean water is consist of 3.5% (m/m) salt, i.e. assuming NaCl (MM = 58.44 g), what would be the freezing point of an ocean? (Kf H2O = 1.86°C m-1)
A. 0.000°C
B. -1.11°C
C. -2.23°C
D. -0.0651°C
NaCl dissociate into “Na^+>Cl^-“
“-Delta>T_f=K_f.m.i”
Where “Delta>T_f=” freezing point depression
“m=” Molarity of the solution
“i=” No. Of particles formed when compound dissolves
“3.5%NaCl=frac{Mass>of>NaCl}{Mass>of>solution}u00d7100%”
“3.5g” of NaCl are dissolved in “96.5g” of water
Gram of NaCl in “1”kg of water
“=frac{1000}{96.5}u00d73.5”
“=36.269g”
Concentration of NaCl “=frac{36.269}{58.44}=0.62062M”
“Delta>T_f=-1.86u00d70.62062u00d72”
“=-2.3087u00b0C”
All options given are wrong.
Unless it is assumed percentage of salt is “3.5%(m/v)” not “(m/m)”
In such a case;
Mass of NaCl in “1kg” of water
“=frac{1000}{100}u00d73.5=35g”
Concentration “=frac{35}{58.44}=0.5989”
“Delta>T_f=1.86u00d70.5989u00d72”
“=-2.23u00b0C”
