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
tensa zangetsu [6.8K]
3 years ago
15

If 1.785 g of ethanol (CHCHOH) is burned in a constant volume calorimeter causing a temperature increase of 4.32C, then what is

the molar heat of combustion in units of kJ/mol of ethanol? (Heat capacity of the calorimeter is 9.49 kJ/C.)
Chemistry
1 answer:
nata0808 [166]3 years ago
7 0

<u>Answer:</u> The enthalpy of the reaction is -1056.44 kJ

<u>Explanation:</u>

To calculate the heat absorbed by the calorimeter, we use the equation:

q=c\Delta T

where,

q = heat absorbed

c = heat capacity of calorimeter = 9.49 kJ/°C

\Delta T = change in temperature =  4.32°C

Putting values in above equation, we get:

q=9.49kJ/^oC\times 4.32^oC=40.99kJ

Heat absorbed by the calorimeter will be equal to the heat released by the reaction.

<u>Sign convention of heat:</u>

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

Given mass of ethanol = 1.785 g

Molar mass of ethanol = 46 g/mol

Putting values in above equation, we get:

\text{Moles of ethanol}=\frac{1.785g}{46g/mol}=0.0388mol

To calculate the enthalpy change of the reaction, we use the equation:

\Delta H_{rxn}=\frac{q}{n}

where,

q = amount of heat released = -40.99 kJ

n = number of moles of ethanol = 0.0388 moles

\Delta H_{rxn} = enthalpy change of the reaction

Putting values in above equation, we get:

\Delta H_{rxn}=\frac{-40.99kJ}{0.0388mol}=-1056.44kJ/mol

Hence, the enthalpy of the reaction is -1056.44 kJ

You might be interested in
What is the OH- ion concentration, in moles per liter, of an aqueous solution with a pH of 7?
topjm [15]

Answer:

B

Explanation:

the pH scale is based on the function

1x10-14

So since pH is neutral the concentration of OH and H must be equal hence the only option in which the concetration would [OH]{H}= 1x10-14 would be when both are equal so it cannot be a or d and when they are expressed in concetration so the only option is B.

3 0
3 years ago
PLZ SOMEONE HELP THANKS:))))<br> materials and conclude which is best to use. Full explanation
grin007 [14]

Answer:

For quick facts use reference materials such as encyclopedias, almanacs, or dictionaries. For credible and reputable information, use online databases of academic journals, or peer-reviewed journal articles that are written by scholars and researchers for a specific discipline.

3 0
2 years ago
A student has two compounds in two separate bottles but with no labels on either one. One is an unbranched alkane, octane, C8H18
Aleks [24]

Answer:

a) both substances are insoluble in water

b) both substances are soluble in ligroin

c) both substances suffer combustion, octane produces more CO₂ than hexene.

d) both substances are less dense than waterl, with hexene having the lowest density.

e) only hexene would react with bromine

f)  only hexene would react with permanganate

Explanation:

a) both substances are non-polar and water is polar

b) both substances are non-polar and lingroin is non-polar

c) C₈H₁₈ + 17.5O₂ → 8CO₂ + 9H₂O

    C₆H₁₂ + 9O₂ → 6CO₂ + 6H₂O

d) water = 997 kg/m³

    ocatne = 703 kg/m³

    hexene = 673 kg/m³

e) bromine test is used to detect unsaturations

f) permanganate test is used to detect unsaturations

7 0
3 years ago
Is ice melting in a drink a chemical change?
konstantin123 [22]
Nope, it's a physical change. When ice melts it changes into liquid water, it's still water. Changes in which no new substances are formed are physical changes, hence this is a physical change.
6 0
3 years ago
What are the 5 principles of kinetic molecular theory?
leva [86]
The kinetic molecular theory<span> of gases is stated in the following four </span>principles<span>: The space between gas </span>molecules<span> is much larger than the </span>molecules<span> themselves. Gas </span>molecules<span> are in constant random motion. The average </span>kinetic<span> energy is determined solely by the temperature.

I got this from my notes from my chemistry class last semester

</span>
8 0
3 years ago
Other questions:
  • Convert 1.25 kg into grams
    11·1 answer
  • The heat of vaporization for ethanol is 0.826 kJ/j. Calculate the heat energy in joules required to boil 45.65g of ethanol
    13·2 answers
  • How many moles of Na2CO3 are in 100.0ml of a 2.0M solution?
    11·1 answer
  • Why do elements in the same group have a similar reactivity?
    9·1 answer
  • Define saturated and unsaturated fats​
    15·2 answers
  • 10
    13·1 answer
  • List the difference between 3 allotropes of carbon
    11·1 answer
  • Aspirin has the formula C9H8O4 If it is decomposed, a product it could never produce is:
    7·1 answer
  • If you have 50 grams of water, how many moles would that be?*
    12·1 answer
  • Because of a scarcity of workers in the New World, persons were transported against their will to work on large farms without pa
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!