Predict the signs of ! ih, , and of the system for the following processes at 1 atm: (a) ammonia melts at - 60°c, (b) ammonia melts at - 77.7°c, and (c) ammonia melts at - 100°c. (the normal melting point of ammonia is - 77.7°c.)

Explanation:

(a) Given,

Normal melting point of ammonia is -77.7 °C

In this process , ammonia melts at - 60°C  

Now , during the process of melting , ammonia in the solid phase changes to liquid phase, and this increases the number of particles , therefore , the sign of entropy would be positive . And since , the process is an endothermic process , hence , the change in enthalphy sign will be positive .

Even , the temperature of the ammonia is more than its normal melting point .

Therefore ,  

TΔS > ΔH

Hence ,

ΔG < 0

Therefore ,  

ΔH = Positive

ΔS = Positive  

ΔG = Negative.

(b)Given,

Normal melting point of ammonia is -77.7 °C

In this process , ammonia melts at -77.7 °C

Now , during the process of melting , ammonia in the solid phase changes to liquid phase, and this increases the number of particles , therefore , the sign of entropy would be positive . And since , the process is neither endothermic process nor exothermic process, hence , the change in enthalphy sign will be neutral / zero .

Hence ,

ΔG < 0

Therefore ,  

ΔH = 0

ΔS = Positive ΔG = Negative.

(c) Given,

Normal melting point of ammonia is -77.7 °C

In this process , ammonia melts at - 100°C  

Now , during the process of melting , ammonia in the solid phase changes to liquid phase, and this increases the number of particles , therefore , the sign of entropy would be positive . And since , the process is an endothermic process , hence , the change in enthalphy sign will be positive .

Even , the temperature of the ammonia is less than its normal melting point .

Hence ,

ΔG > 0

Therefore ,  

ΔH = Positive

ΔS = Positive  

ΔG = Negative.

Step-by-step explanation:

A mathematics teacher wanted to see the correlation between test scores and homework. The homework grade (x) and test grade (y) are given in the accompanying table. Write the linear regression equation that represents this set of data, rounding all coefficients to the nearest tenth. Using this equation, estimate the homework grade, to the nearest integer, for a student with a test grade of 31.

Homework Grade (x) Test Grade (y)

58 52

75 66

66 68

85 74

52 38

74 65

78 76