What is the freezing point of a solution of 7.15 g MgCl2 in 100 g of water? K f for water is 1.86°C/m. What is the freezing point of a solution of 7.15 g MgCl2 in 100 g of water? K f for water is 1.86°C/m. -0.140°C -4.18°C -1.40°C -2.80°C

-1.4°C

Explanation:

From;

∆T f= K f × m

∆T f= freezing point depression

K f= freezing point depression constant

m= molality of the solution

Number of moles of MgCl2= 7.15g/95gmol-1 = 0.075 moles

Molality= 0.075 moles/ 0.1 kg of water = 0.75 m

∆T f= -1.86 °C/m × 0.75= -1.395°C = -1.4°C

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.