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Sidana [21]
3 years ago
11

The combustion of 0.25 mol of an unknown organic compound results in the release of 320 kJ of energy. Which of the compounds in

the table could be the unknown compound?
A.methane
B.ethylene
C.ethanol
Chemistry
2 answers:
vichka [17]3 years ago
5 0

Answer: C. ethanol

The enthalpy of combustion is the amount of heat produced when one mole of ethanol undergoes complete combustion at 25 ° C and 1 atmosphere pressure, yielding products also at 25 ° C and 1 atm.

<u>The enthalpy of combustion of the unknown compound is</u>

ΔH = - 320 kJ / 0.25 mol = - 1280 kJ / mol

<u>To choose a probable compound according to this combustion enthalpy, we must evaluate the deviation in relation to the values reported in the literature for the three probable compounds</u> (methane, ethylene and ethanol). The deviation (e%) will be calculated according to the following equation,

e% =  ( | ΔHx - ΔH | / ΔHx ) x 100%

where ΔHx is the enthalpy of combustion of the probable compound.

The following table shows the combustion enthalpies of the probable compounds and their deviation in relation to the enthalpy of ΔH = - 1280 kJ / mol

Compound Enthalpy of combustion (kJ/mol)   Deviation

Methane                        - 890.7                                 43.8%

Ehylene                         -1411.2                                   9.3%

Ethanol                        -1368.6                                    6.5%

According to the previous table, we can say that the most probable compound is ethanol, since it has the smallest deviation in relation to the experimental enthalpy value of combustion.

zalisa [80]3 years ago
3 0

Answer:

C.) Ethanol

Explanation:

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How are the melting points and boiling points of molecular compounds usually different from those of ionic compounds
pentagon [3]
Melting points and boiling points of molecular compound are usually lower than ionic compounds. This is so as only a small amount of energy is required to overcome the weak intermolecular forces of attraction (Van de Waals forces) thus having lower m.p. and b.p.

Ionic compounds require a large amount of energy to overcome the strong electrostatic forces of attraction between the ions, hence having higher mp and bp
6 0
3 years ago
1. What Volume of HCl is generated if 3.44 g of Cl2 are reacted at STP? 2. What volume does 4.87 mol of Kr have at STP? 3. What
IgorLugansk [536]

Answer:

1. 2.17 dm3 VOLUME OF HCl IS PRODUCED WHEN 3.44 g OF Cl2 REACT AT STP

2. 4.87 MOLE OF Kr AT STP CONTAINS 109.088 dm3 .

3. THE PRESSURE WHEN 3.44 g OF Cl2 are reacted at 4.55 L AT 455 K IS 0.77 atm

Explanation:

1 Volume of HCl if 3.44 g of Cl2 are reacted at STP?

Equation for the reaction:

H2 + Cl2 ---------> 2HCl

1 mole of Cl2 reacts to form 2 mole of HCl

At STP, 1 mole of a gas is equal to the molar mass of the gas sample

35.5 * 2 g of Cl2 reacts to form 2 mole of HCl

3.44 g of Cl2 will react to form  ( 3.44 * 2 / 71 ) mole of HCl

= 0.0969 mole of HCl

1 mole of HCl = 22.4 dm3

0.0969 mole of HCl = ( 22.4 * 0.0969 / 1)

= 2.17056 dm3

The volume of HCl is 2.17 dm3 when 3.44 g of Cl2 are reacted at STP.

2. What volume does 4.87 mol of Kr have at STP?

1 mole of a substance is 22.4 dm3 of the sample

1 mole of Kr = 22.4 dm3

4.87 mole of  Kr = 4.87 * 22.4

= 109.088 dm3

4.87 mole of Kr at STP contains 109.088 dm3 volume

3. Whta pressure of HCl is generated if 3.44 g of Cl2 are reacted at 4.55 L at 455 K

Using the formula:

PV = nRT

V = 4.55 L

R = 0.082 L atm/ mol K

T = 455 K

m = 3.44 g

n = mass / molar mass

molar mass = ( 1 + 35.5) = 36.5 g/mol

n = 3.44 g / 36.5 g/mol

n = 0.094 mole

P = nRT / V

P = 0.094 * 0.082 * 455 / 4.55

P = 3.50714 / 4.55

P = 0.7708 atm

The pressure of HCl if 3.44 g of Cl2 are reacted at 4.55 L and 455 K is 0.7708 atm.

8 0
2 years ago
Assign oxidation numbers to the element in each of the following compounds. Remember an oxidation number is for one atom of the
worty [1.4K]

Answer:

a.  x = + 2

b.  x = + 3

c.  x = + 2

d.  x = + 3

Explanation:

The oxidation number is a formal charge assigned to an atom present in a molecule or formula unit or ion based on some arbitrary rules.

a.

<u>Hg</u>O

The oxidation number of Hg in HgO is:

x + (-2) = 0

x = +2

b.

<u>Al₄</u>C₃

The oxidation number of Al in Al<u>₄</u>C₃ is:

4x +(3 × -4) = 0

4x - 12 = 0

4x = +12

x = 12/4

x = +3

c. CrF₂

x + ( 2 × - 1) = 0

x - 2 = 0

x = + 2

d. Fe₂S₃

2x + ( 3 × - 2) = 0

2x + (-6) = 0

2x = 6

x = 6/2

x = +3

7 0
3 years ago
How many meters are in ten cm?
ser-zykov [4K]

Answer: 0.1 meters

Explanation: move ten down a place value and u get .10 which is equal to 0.1 meters

7 0
3 years ago
Which two elements on the periodic table are in the same period?
emmainna [20.7K]

Answer:

Platinum and Gold ig.

6 0
3 years ago
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