1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
kicyunya [14]
3 years ago
9

Ethanol (C2H5OH) melts a - 144 oC and boils at 78 °C. The enthalpy of fusion of ethanol is 5.02 kj/mol, and its enthalpy of vapo

rization is 38.56 kj/mol. The specific heats of solid and liquid ethanol are 0.97j/g - k and 2.3 j/g - K, respectively.
(a) How much heat is required to convert 42.0 g of ethanol at 35 °C to the vapor phase at 78 °C?

(b) How much heat is required to convert the same amount of ethanol at - 155 oC to the vapor phase at 78 °C?
Chemistry
1 answer:
Romashka [77]3 years ago
7 0

<u>Answer:</u>

<u>For a:</u> The total heat required is 36621.5 J

<u>For b:</u> The total heat required is 58944.5 J

<u>Explanation:</u>

  • <u>For a:</u>

To calculate the heat required at different temperature, we use the equation:

q=mc\Delta T         .........(1)

where,

q = heat absorbed

m = mass of substance

c = specific heat capacity of substance

\Delta T = change in temperature

To calculate the amount of heat required at same temperature, we use the equation:

q=m\times \Delta H      ........(2)

where,

q = heat absorbed

m = mass of substance

\Delta H = enthalpy of the reaction

The processes involved in the given problem are:

1.)C_2H_5OH(l)(35^oC)\rightarrow C_2H_5OH(l)(78^oC)\\2.)C_2H_5OH(l)(78^oC)\rightarrow C_2H_5OH(g)(78^oC)

  • <u>For process 1:</u>

We are given:

Change in temperature remains the same.

m=42.0g\\c_l=2.3J/g.K\\T_2=78^oC\\T_1=35^oC\\\Delta T=[T_2-T_1]=[78-35]^oC=43^oC=43K

Putting values in equation 1, we get:

q_1=42.0g\times 2.3J/g.K\times 43K\\\\q_1=4153.8J

  • <u>For process 2:</u>

We are given:

Conversion factor: 1 kJ = 1000 J

Molar mass of ethanol = 46 g/mol

m=42.0g\\\Delta H_{vap}=38.56kJ/mol=\frac{35.56kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=773.04J/g

Putting values in equation 2, we get:

q_2=42.0g\times 773.04J/g\\\\q_2=32467.7J

Total heat required = [q_1+q_2]

Total heat required = [4153.8J+32467.7J]=36621.5J

Hence, the total heat required is 36621.5 J

  • <u>For b:</u>

The processes involved in the given problem are:  

1.)C_2H_5OH(s)(-155^oC)\rightarrow C_2H_5OH(s)(-144^oC)\\2.)C_2H_5OH(s)(-144^oC)\rightarrow C_2H_5OH(l)(-144^oC)\\3.)C_2H_5OH(l)(-144^oC)\rightarrow C_2H_5OH(l)(78^oC)\\4.)C_2H_5OH(l)(78^oC)\rightarrow C_2H_5OH(g)(78^oC)

  • <u>For process 1:</u>

We are given:

Change in temperature remains the same.

m=42.0g\\c_s=0.97J/g.K\\T_2=-144^oC\\T_1=-155^oC\\\Delta T=[T_2-T_1]=[-144-(-155)]^oC=11^oC=11K

Putting values in equation 1, we get:

q_1=42.0g\times 0.97J/g.K\times 11K\\\\q_1=448.14J

  • <u>For process 2:</u>

We are given:

m=42.0g\\\Delta H_{fusion}=5.02kJ/mol=\frac{5.02kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=109.13J/g

Putting values in equation 2, we get:

q_2=42.0g\times 109.13J/g\\\\q_2=4583.5J

  • <u>For process 3:</u>

We are given:

Change in temperature remains the same.

m=42.0g\\c_l=2.3J/g.K\\T_2=78^oC\\T_1=-144^oC\\\Delta T=[T_2-T_1]=[78-(-144)]^oC=222^oC=222K

Putting values in equation 1, we get:

q_3=42.0g\times 2.3J/g.K\times 222K\\\\q_3=21445.2J

  • <u>For process 4:</u>

We are given:

m=42.0g\\\Delta H_{vap}=38.56kJ/mol=\frac{38.56kJ}{1mol}\times (\frac{1000J}{1kJ})\times (\frac{1}{46g/mol})=773.04J/g

Putting values in equation 2, we get:

q_4=42.0g\times 773.04J/g\\\\q_4=32467.7J

Total heat required = [q_1+q_2+q_3+q_4]

Total heat required = [448.14+4583.5+21445.2+32467.7]J=58944.5J

Hence, the total heat required is 58944.5 J

You might be interested in
Convert mass to moles for both reactants. (Round to 2 significant figures.)
shepuryov [24]
Mass = mr x moles
Mr of CuCl2 = ( 63.5) + ( 35.5 x 2) = 134.5
2.5 = 134.5 x moles
2.5 / 134.5 = moles
Moles = 0.019 (2DP)

0.25g of Al
Mr of Al = 27
0.25 = 27 x moles
0.25/ 27 = 0.0093 moles (2sf)

Hope this helps :)
6 0
3 years ago
Read 2 more answers
Describe in your own words, in terms of particle movement and energy, what occurs when a liquid is cooled to its freezing point.
IRINA_888 [86]
Liquids have free and fast moving particles. Liquids do not take a specific shape unless they are enclosed such as in a bottle. Anyway, since they are free flowing when they freeze, their movement becomes very slow. Eventually the particles will not have room to move as they used to and will be held in one place. The particles are still moving but they are only shaking or vibrating in the same place. You can't even tell this movement is happening, and that is what happens when liquid freezes.

4 0
3 years ago
when some ionic salts are dissolved in water the reaction is exothermic when others are dissolved in water the reaction is endot
antiseptic1488 [7]
One type of chemical process that can be either exothermic or endothermic is dissolving of salts in water. A salt is a compound made up of positively charged ions and negatively charged ions which are held together in a solid state because the positive and negative charges attract one another.
5 0
3 years ago
Which of the following is not a reason for extinction?
Rashid [163]

Answer:

the ability to breed successfully

Explanation:

3 0
2 years ago
Read 2 more answers
Which of the following is not found in the nucleus of an atom?
DochEvi [55]
Electron -  In an atom, the central part which is composed of neutrons and protons including quarks is called the nucleus. Whereas the electron is the particle with negative elementary electric charge can be found inside the atom surrounding the nucleus. 
6 0
3 years ago
Other questions:
  • Which of the following statements is true of water in a solid state? Choose all that apply.
    15·1 answer
  • During the time 0.325 mol of an ideal gas undergoes an isothermal compression at 22.0∘c, 352 j of work is done on it by the surr
    12·1 answer
  • Molarity is represented by the symbol m true or false?
    11·2 answers
  • Is baking soda less, or more denser than water?
    9·2 answers
  • igneous rocks that are dense and dark-colored thet form from magma that is rich in iron and magnesium and poor in silica
    15·2 answers
  • Greg checks his watch one day at noon when the Sun is directly overhead. He decides to check his watch when the Sun is directly
    14·1 answer
  • Which observation provided Albert Einstein the clue that he needed to explain the photoelectric effect? Light is made up of extr
    9·2 answers
  • Why metals are denser than non - metals ? ...?
    8·1 answer
  • What is the bond angle that corresponds to the
    9·1 answer
  • Solid ammonium chloride, NH4Cl, is formed by the reaction of gaseous ammonia, NH3, and hydrogen chloride, HCl. NH3(g)+HCl(g)⟶NH4
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!