Answer to Question #207897 in Physical Chemistry for Kareena Max

Question

Magnesium oxide and nickel oxide withstand high temperatures. However, they do melt when the temperature is high enough and the behavior of mixtures of the two is of considerable interest to the ceramics industry. Draw the temperature composition diagram for the system using the data below, where x is the mole fraction of MgO in the solid and y its mole fraction in the liquid. /C 1960 2200 2400 2600 2800 x 0 0.35 0.60 0.83 1.00 y 0 0.18 0.38 0.65 1.00 State (a) the melting point of a mixture with x = 0.30, (b) the composition and proportion of the phases present when a solid of composition x = 0.30 is heated to 2200C, (c) the temperature at which a liquid of composition y = 0.70 will begin to solidify.

Answer 1

These are the properties of MgO and NiO phase diagram plot. Liquidus temperature is the temperature above which the system is entirely liquid, and the solidus is the temperature below which the system is completely solid. Between these two points the liquid and solid phases are in equilibrium.

a) at x= .30 the melting point is 2150.

b)The composition of the solid can be found by drawing a vertical line to the base of the diagram. Thus it is seen that the first crystals precipitated from composition X will have the composition.

% solid = [x/(x + y)] x 100

c) the y=.70 is 2650