Answer:
(a) Hypoeutectic
(b) Alpha solid, aluminium
(c) 70% α
, 30% β
(d) 97.6% α, 2.4% β
(e) 97.6% α, 2.4% β
(f) 97% α, 3% β
Explanation:
(a) The eutectic composition for Al Si alloy is 11.7 wt% silicon, therefore, an Al-4% Si alloy is hypoeutectic
(b) For the hypoeutectic alloy, aluminium, Al, is expected to form first, such that the aluminium content is reduced till the point it gets to the eutectic proportion of 11.7 wt% silicon
(c) At 578°C we have
% α: Al (11 - 4)/(11 - 1) = 70% α
% L: Si 100 - 70 = 30% β
(d) At 576°C we have
α: 99.83% Si (99.83 - 4)/(99.83- 1.65) = 97.6% α
β: 1.65% Si (4 - 1.65)/(99.83- 1.65) = 2.4% β
(e) Primary α: 1.65% α (99.83 - 4)/(99.83 - 1.65) = 97.6% α
Eutectic 4% Si = 100 - 97.6 = 2.4% β
(f) At 25°C we have;
α%: (99.83 - 4)/(99.83 - 1) = 97% α
β%: 100 - 97 = 3% β.
Answer:
THE TEMPERATURE AT WHICH THE CHEMICAL REACTION IS BEING CONDUCTED.
Explanation:
The reaction rate constant is dependence on the temperature in which the reaction takes place. The rate of a reaction and the activation energy relationship is given by the Arrhenius equation with the rate constant as a function of temperature.
Mathematically, the rate constant is expressed as;
k(T) = Ae^-Ea/RT
where Ea is the activation energy, R is the gas constant, Ae is the pre-exponential factor and it is the frequency at which a reactant molecule collide with each other, T is the temperature.
The balanced chemical reaction is written as:
P4 + 10Cl2 = 4PCl5
To determine the moles of PCl5 produced, we use the initial amount of the limiting reactant which is P4 and the relation from the reaction. We do as follows:
22.0 g P4 ( 1 mol / 123.90 g ) ( 4 mol PCl5 / 1 mol P4 ) = 0.7103 mol PCl5 produced
Depression in freezing point (Δ
) =
×m×i,
where,
= cryoscopic constant =
,
m= molality of solution = 0.0085 m
i = van't Hoff factor = 2 (For
)
Thus, (Δ
) = 1.86 X 0.0085 X 2 =
Now, (Δ
) =
- T
Here, T = freezing point of solution
= freezing point of solvent =
Thus, T =
- (Δ
) = -
