1. Calculate the amount of heat necessary to raise the temperature of 135.0 g of

Question

1. Calculate the amount of heat necessary to raise the temperature of 135.0 g of water from 50.4 degrees Farenheit to 85.0 degrees Farenheit. The specific heat of water = 4.184 J/g. degrees Celsius

A) 48.0kJ
B) 1.1kJ
C) 10.9kJ
D) 16.6 kJ
E) 19.5 kJ

2) Which of the following processes always results in an increase in the energy of a system?
A) The system loses heat and has to work done on it by the surroundings
B) The system gains heat and does work on the surroundings?
C) The system gains heat and has work done on it by the surroundings
D) None of these is always true
E) The system loses heat and does work on the surroundings

3) Deviations from the ideal gas law are greater at
A) low temperature and low pressures
B) high temperatures and low pressures
C) high temperatures and high pressures
D) low temperatures and high pressures

Explanation / Answer

Answer – 1) We are given, mass of water = 135.0 g , initial temp, ti = 50.4oF, tf = 85.0 oF, specific heat of water , C= 4.184 J/g. degrees Celsius

Now we need to convert the temp degree Farenheit to degree Celsius

We know

1 oF = -17.22oC

So, 50.4oF = 10.22 oC

85.0 oF = 29.44 oC

We know formula

Heat, q = m* C*t

            = 135.0 g * 4.184 J/g oC * ( 29.44 -10.22) oC

            = 10856.2 J

        = 10.9 kJ

So, the amount of heat necessary to raise the temperature of 135.0 g of water from 50.4 degrees Farenheit to 85.0 degrees Farenheit is C) 10.9kJ

2) We need to look for the system which processes always results in an increase in the energy of a system.

The system gains heat and has work done on it by the surroundings processes always results in an increase in the energy of a system, since we know the increase in the energy of a system means the system absorbing the heat from the surrounding or external source and work done on surrounding. So answer for this one is option C

3) Deviations from the ideal gas law are greater at high temperatures and low pressures, because we know as we increase the temperature their kinetic energy of gas molecule increase and they go apart from each other and there is no much longer intermolecular force and as we decrease the pressure gas molecules again goes apart from each other and there is no much longer intermolecular force. When gas molecules are separating from to each other, then there are not obeying the ideal law means there is showing deviation.

So answer for this one is option B.

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