Answer: [tex]\Delta H_{rxn}=-4652[/tex] kJ/mol
Explanation: In a reaction, a bond of a molecule can break or rearrange itself. When it happens, it absorb or release energy.
Bond Energy is the energy necessary to break or to make a particular bond, producing gaseous fragments at atmospheric temperature. This type of energy can be used to show how stable a compound is or how easy a bond can break.
Enthalpy of Reaction is the energy absorption or release at a constant temperature resulting from a chemical reaction.
To calculate the Enthalpy using bond energy, you have:
1) Write the balanced equation with all the all the reactants and products in gaseous form:
[tex]C_{5}H_{12}_{(g)}+8O_{2}_{(g)}[/tex] ⇒ [tex]5CO_{2}_{(g)}+6H_{2}O_{(g)}[/tex]
2) Count each bond of each molecule from both sides, including double or triple bonding, if they exists:
Reactants:
[tex]C_{5}H_{12}[/tex] : 12 C-H
4 C-C
O₂ : 1 O=O
Products:
CO₂ : 2 C=O
H₂O : 2 H-O
3) From the balanced reaction, we there are 8 moles of oxygen gas, 5 moles of carbon dioxide and 6 moles of water, which has to be included when adding each side.
[tex]\Sigma H_{reactants}=[/tex] 12.257 + 4.370 + 8.490 = 8484
[tex]\Sigma H_{products}=[/tex] 5.2.740 + 6.2.478 = 13136
4) Calculate Enthalpy of Reaction by:
[tex]\Delta H_{rxn}= \Sigma H_{reactants}-\Sigma H_{products}[/tex]
[tex]\Delta H_{rxn}=8484-13136[/tex]
[tex]\Delta H_{rxn}=-4652[/tex]
The enthalpy of reaction for the combustion of 1 mole of pentane on a just discovered imaginary planet is an exothermic process of magnitude [tex]\Delta H_{rxn}=[/tex] - 4652kJ/mol
Using the planet's given bond energies to calculate the enthalpy of reaction, the combustion of 1 mole of pentane is -4652 kJ.
The balanced chemical reaction for the combustion of pentane is well represented as:
[tex]\mathbf{C_5H_{12}+8O_2 \to 5CO_2+6H_2O}[/tex]
From the above reaction, the bonds broken are 12 Carbon-Hydrogen bonds, 4 Carbon-Carbon bonds, and 8 oxygen-oxygen bonds.
Similarly, the bonds formed are 10 Carbon-Oxygen bonds and 12 Oxygen-hydrogen bonds.
Hence, the energy absorbed when bonds are broken are:
= 12(C-H) + 4(C-C) + 8(O-O)
= 12(257 kJ) + 4(370 kJ) + 8(490 kJ)
= 3084 kJ + 1480 kJ+ 3920 kJ
= 8484 kJ
Also, the energy released as a result of the formation of bond is:
= 10 (C=O) + 12 (O-H)
= 10 (740 kJ) + 12 (478 kJ)
= 7400 kJ + 5736 kJ
= 13136 kJ
From above, we can notice that the energy released during the formation of bonds is greater than the energy absorbed while breaking bonds.
Thus, the enthalpy of the combustion reaction is the difference in energy.
i.e.
The enthalpy of the combustion reaction = 8484 kJ - 13136 kJ
= -4652 kJ
Therefore, we can conclude that the enthalpy of reaction from the combustion of 1 mole of pentane is -4652 kJ. The negative sign indicates that more energy is released compared to the amount of energy absorbed.
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When a mixture of rock pieces, salt and water is filtered, what will be found as the filtrate and what will be found as the residue
Answer:
Filtrate: Mixture of salt and water.
Residue: rock pieces
Answer:
Salt solution will be the filtrate
and the rock pieces will be the residue.
Explanation:
This is because salt is soluble in water and hence
it cannot be filtered out of water giving as a salt solution as the filtrate and since the rock pieces are not soluble in water they are left out and they become the residue.
why sodium chloride has a hiegher melting point
Answer:
Explanation:
Sodium chloride has a high melting and boiling point
There are strong electrostatic attractions between the positive and negative ions, and it takes a lot of heat energy to overcome them. Ionic substances all have high melting and boiling points.
Hybridization of carbons in CH3-CH= C = CH2 is
a) sp3sp3, sp2 sp2
b) sp3. sp2, sp, sp3
c) sp3, sp3, sp2, sp3
d) sp3, sp2, sp, sp1
Answer:
A carbon atom bound to three atoms (two single bonds, one double bond) is sp2 hybridized and forms a flat trigonal or triangular arrangement with 120° angles between bonds. Notice that acetic acid contains one sp2 carbon atom and one sp3 carbon atom.
Molecules have Question 8 options: A) only kinetic energy. B) neither kinetic nor potential energy. C) only potential energy. D) both potential and kinetic energy.
What is the freezing point in °C) of a 0.195 m
aqueous solution of K2S?
Enter your rounded answer with
3 decimal places.
K for water = 1.86 °C/m
Answer:
[tex]T_S=-1.09\°C[/tex]
Explanation:
Hello!
In this case, since the freezing point depression for a solution is computed via:
[tex](T_S-T_W)=-imK_f[/tex]
Whereas TW is the freezing temperature of water, TS that of the solution, i the van't Hoff's factor (3 for K2S as it ionizes properly), m the molality of the solution and Kf the freezing point constant of water. Thus, we plug in to obtain:
[tex](T_S-0\°C)=-3*0.195m*1.86\frac{\°C}{m}\\\\T_S=-1.09\°C[/tex]
Best regards!
The correct answer is -1.088. (Don't forget the negative sign).
How many moles of a solute is contained in 500mL of a 2.5 M solution?
Answer:
100M
Explanation:
What mass of nitrogen occupies a volume of 11.2 L, if 4.20 g of nitrogen occupies 100. L?
Answer:
0.47 g
Explanation:
From the question given above, we obtained the following information:
4.20 g of nitrogen occupies 100 L.
We can obtain the mass of nitrogen that occupied 11.2 L by doing the following:
4.20 g of nitrogen occupies 100 L.
Therefore, Xg of nitrogen will occupy 11.2 L i.e
Xg of nitrogen = (11.2 × 4.2) / 100
Xg of nitrogen = 0.47 g
From the calculation made above, 0.47 g of nitrogen will occupy 11.2 L
How many neutrons are there in a neutral argon atom? Show how you found your answer on your scratch paper.
Molecules Have?
A. Only kinetic energy
B. Only potential energy
C. Both kinetic and potential energy
D. Neither potential nor kinetic
Answer:
C
Explanation:
Because molecules of solids don't move
while molecules of liquids and gases move.
I Hope this helps!!.
PLS HALP ASAP points
Answer:
50 N ( left)
Explanation:
Given data:
The force on right side = 450 N
The force on left side = 500 N
Net force = ?
Solution:
F (net) = 500 N - 450 N
F (net) = 50 N ( left)
How many grams are 1.2 x 10^-2 moles of K3PO4
Answer:
2.5471951319999997
Explanation:
What is the degree of oxidation of a simple substance
Answer: The oxidation state of a free element (uncombined element) is zero. For a simple (monoatomic) ion, the oxidation state is equal to the net charge on the ion. For example, Cl– has an oxidation state of -1. When present in most compounds, hydrogen has an oxidation state of +1 and oxygen an oxidation state of −2.
Hope this helps...... Stay safe and have a Merry Christmas!!!!!!!!!!! :D
Explanation:
What is the characteristic of atoms
Answer:
Most of the atom is empty space. The rest consists of a positively charged nucleus of protons and neutrons surrounded by a cloud of negatively charged electrons. The nucleus is small and dense compared with the electrons, which are the lightest charged particles in nature.
Why do you organisms live in deep water bottom zone Of Standing water ecosystems
Answer:
Deeper water, where too little sunlight penetrates for photosynthesis, is called the aphotic zone. Surface water dissolves oxygen from the air, so there is generally plenty of oxygen in the photic zone to support organisms. Water near shore usually contains more dissolved nutrients than water farther from the shore
Explanation:
In which type of mirror do you see the most realistic virtual image
Plane
Convex
Concave
Duplex
Phan
convex
concave
duplex
What happens when sodium and sulfur combine?
A) each sodium atom gains one electron
B) each sulfur atom loses one electron
C) each sodium atom loses one electron
D) each sulfur atom gains one electron
Answer:
BBBBBBBB ITS B
Explanation:
Oxidation of a secondary alcohol results in the formation of a(n):________. a) tertiary alcohol b) acid c) aldehyde d) ketone
Answer:
A. Tertiary alcohol
Explanation:
Secondary alcohols are oxidized to ketones - and that's it. For example, if you heat the secondary alcohol propan-2-ol with sodium or potassium dichromate(VI) solution acidified with dilute Sulphuric acid, you get propanone formed. Playing around with the reaction conditions makes no difference whatsoever to the product.
Does the octet rule state that all elements except Hydrogen and Helium want eight (8) valence electrons?
Answer:
yes
Explanation:
Which of the following equations is balanced?
Answer:
wheres the image
Explanation:
What type of radioactive decay will the isotopes 13B and 188Au most likely undergo?
a. Beta emission, positron emission
b. Beta emission, beta emission
c. Positron emission, beta emission
d. Positron emission, positron emission
Answer:
b. Beta emission, beta emission
Explanation:
A factor to consider when deciding whether a particular nuclide will undergo this or that type of radioactive decay is to consider its neutron:proton ratio (N/P).
Now let us look at the N/P ratio of each atom;
For B-13, there are 8 neutrons and five protons N/P ratio = 8/5 = 1.6
For Au-188 there are 109 neutrons and 79 protons N/P ratio = 109/79=1.4
For B-13, the N/P ratio lies beyond the belt of stability hence it undergoes beta emission to decrease its N/P ratio.
For Au-188, its N/P ratio also lies above the belt of stability which is 1:1 hence it also undergoes beta emission in order to attain a lower N/P ratio.
Radioactive decay refers to the loss of energy by an unstable atomic nucleus as radiation. The substance having unstable nuclei is radioactive.
The correct answer is:
Option B. Beta emission, beta emission
The radioactive decay of 13B and 188 Au can be explained as:
1. Neutron proton ratio refers to the particular nuclei that will undergo what type of radioactive decay.
For B-13, there are 8 neutrons and 5 protons, thus, the ratio is 1.6.For Au -188, there are 109 neutrons and 79 protons, thus, the ratio is 1.4.2. In the B-13 element, the N/P ratio is beyond the stability of the atom, thus, it will emit beta emission to reduce the N/P ratio.
3. Similarly, the N/P ratio of the Au-188 is above the stability of the atom, thus, it undergoes the beta emission to reduce the N/P ratio.
Thus, the correct answer is Option B.
To know more about radioactive decay, refer to the following link:
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3. A reaction of the type X → Y + Z has a rate constant k = 3.6 x 10-5 M/s. Determine
molarity of x after a reaction time of 30.0 min if the initial concentration of x is
0.096M
(3 marks)
Answer:
0.16 M.
Explanation:
Hello!
In this case, since the reaction can be determined as zeroth-order because of the units of M/s, we can write the rate law as:
[tex][X]=[X]_0-kt[/tex]
In such a way, since we need the initial concentration of X, we proceed as follows:
[tex][X]_0=[X]+kt[/tex]
So we plug in to obtain:
[tex][X]_0=0.096M+3.6x10^{-5}\frac{M}{s}*30.min*\frac{60s}{1min}[/tex]
[tex][X]_0=0.16M[/tex]
Best regards!
The equilibrium constant, Kc, for the following reaction is 1.29E-2 at 600 K. COCl2(g) CO(g) Cl2(g) Calculate the equilibrium concentrations of reactant and products when 0.280 moles of COCl2(g) are introduced into a 1.00 L vessel at 600 K. [COCl2]
Answer:
At Equilibrium
[COCl₂] = 0.226 M
[CO] = 0.054 M
[Cl₂] = 0.054 M
Explanation:
Given that;
equilibrium constant Kc = 1.29 × 10⁻² at 600k
the equilibrium concentrations of reactant and products = ?
when 0.280 moles of COCl2(g) are introduced into a 1.00 L vessel at 600 K. [COCl²]
Concentration of COCl₂ = 0.280 / 1.00 = 0.280 M
COCl₂(g) ----------> CO(g) + Cl₂(g)
0.280 0 0 ------------ Initial
-x x x
(0.280 - x) x x ----------- equilibrium
we know that; solid does not take part in equilibrium constant expression
so
KC = [CO][Cl₂] / COCl₂
we substitute
1.29 × 10⁻² = x² / (0.280 - x)
0.0129 (0.280 - x) = x²
x² = 0.003612 - 0.0129x
x² + 0.0129x - 0.003612 = 0
x = -b±√(b² - 4ac) / 2a
we substitute
x = [-(0.0129)±√((0.0129)² - 4×1×(-0.003612))] / [2 × 1 ]
x = [-0.0129 ± √( 0.00017 + 0.01445)] / 2
x = [-0.0129 ± 0.1209] / 2
Acceptable value of x =[ -0.0129 + 0.1209] / 2
x = 0.108 / 2
x = 0.054
At equilibrium
[COCl₂] = (0.280 - x) = 0.280 - 0.054 = 0.226 M
[CO] = 0.054 M
[Cl₂] = 0.054 M
A fish company delivers 15 kg of salmon 4.7 kg Of crab and 1.76 kg of oysters to your seafood restaurant what is the total mass in kilograms of the seafood
Answer:
21.46 kg.
Explanation:
Hello!
In this case, when a variety of measurements are said to contribute to a total, we understand we need to add them all up in order to get that total; in such a way, since the given seafood is composed by 15 kg of salmon, 4.7 kg of crab and 1.76 kg of oysters, the total mass turns out:
[tex]m_T=15kg+4.7kg+1.76kg\\\\m_T=21.46kg[/tex]
Best regards!
How many oxygen atoms are represented by the formula Fe(CIO4)3? iron(III) chlorate
3
16
12
4
Answer:
12
Explanation:
the 4 by the element symbol O multiplied by the 3 on the outside of the parentheses
Answer:
[tex]\boxed {\boxed {\sf C. \ 12 \ oxygen \ atoms }}[/tex]
Explanation:
We are given the chemical formula:
[tex]Fe(ClO_4)_3[/tex]
There are 3 elements here:
Fe: Iron Cl: ChlorineO: OxygenThe question asks for the number of oxygen atoms, so we can just focus on the O in the formula.
The O has a subscript of 4, indicating there are 4 oxygen atoms in the compound. But the compound is also enclosed in parentheses with a subscript of 3. Therefore, there are 3 of the compounds with 4 oxygen atoms.
We can multiply 3 and 4.
3*4= 12There are 12 oxygen atoms.
Element X has two known isotopes. If 83% of the sample weighs 76 amu and the remaining 17% weighs 73.6 amu, what is the atomic mass of element X
Answer:
The atomic mass of an element is the average mass of the atoms of an element measured in atomic mass unit (amu, also known as daltons, D). The atomic mass is a weighted average of all of the isotopes of that element, in which the mass of each isotope is multiplied by the abundance of that particular isotope. (Atomic mass is also referred to as atomic weight, but the term "mass" is more accurate.)
Q. The entropy of the system will usually increase when
answer choices
A)a molecule is broken into two or more smaller
molecules
B)a reaction occurs that results in an increase in
the number of moles of gas
C)a solid changes to a liquid
D)all of these
Answer:
D
Explanation:
The base that will NOT combine with 2-deoxyribose to form a nucleic acid is _____.
Answer:
Uracil
Explanation:
The base that will NOT combine with 2-deoxyribose to form a nucleic acid is Uracil.
2-deoxyribose is a pentose sugar found in the DNA (Deoxyribonucleic acid). It is devoid of oxygen in its 2' position. The bases found in DNA are Adenine, Guanine, Cytosine and Thymine. Adenine, Guanine, and Cytosine are also found in RNA (Ribonucleic acid). Thymine is not present in RNA, it is only found in DNA. The base found in RNA is Uracil which in turn is not present in DNA. The five carbon sugar present in RNA is ribose which combines with Uracil.
Which one is a decomposition reaction?
Answer:
b no
Explanation:
because it is decomposing into two elements
Which segment of this graph shows a decreasing velocity?
Answer:
The segment of this graph that shows a decreasing velocity is the EF segment. AB and DE segments show that whatever was moving, in these segments was stopped. The segment BC shows an increase in velocity - the metres travelled were always more as the time went by.
Explanation:
The enthalpy change of formation of carbon dioxide is –394 kJ mol–1. The enthalpy change of formation of water is –286 kJ mol–1. The enthalpy change of formation of methane is –74 kJ mol–1. What is the enthalpy change of combustion of methane?
The enthalpy change of combustion of methane : -892 kJ/mol
Further explanationThe change in enthalpy in the formation of 1 mole of the elements is called enthalpy of formation
The enthalpy of formation measured in standard conditions (25 ° C, 1 atm) is called the standard enthalpy of formation (ΔHf °)
Determination of the enthalpy of formation of a reaction can be through a calorimetric experiment, based on the principle of Hess's Law, enthalpy of formation table, or from bond energy data
The value of ° H ° can be calculated from the change in enthalpy of standard formation:
∆H ° rxn = ∑n ∆Hf ° (product) - ∑n ∆Hf ° (reactants)
Reaction for combustion of Methane (CH₄) :
CH₄ + 2O₂ → CO₂ + 2H₂O.
The elements in standard conditions are not included in the enthalpy calculations because the enthalpy of those elements under the standard conditions is zero(∆Hf °O₂ =0)
∆Hf ° CO₂ = -394 kj/mol
∆Hf ° H₂O=-286 kj/mol
∆Hf ° CH₄=-74 kJ/mol
The enthalpy change of combustion of methane :
[tex]\tt \Delta H_{rxn}=\Delta H_f~CO_2+2.\Delta H_fH_2O-(\Delta H_fCH_4)\\\\\Delta H_{rxn}=(-394-2.-286)-(-74)\\\\\Delta H_{rxn}=-892~kJ/mol[/tex]
Answer:
-655
Explanation:
ye