When 3.93 grams of lactic acid, CHoOs(s), are burned in a bomb
calorimeter that has a total heat capacity of 10.80 kJ-K-1, the
temperature of the calorimeter increases by 5.43 K. Assume AHrxn
=
AErxn. Given that AH°f of H¿O(I) = -285.8 kJ-mol-1 and AH°f of CO:(g)
= -393.5 kJ• mol-1, calculate the AH°f of lactic acid.
Answers
The heat released in the combustion of lactic acid is absorbed by the
calorimeter and in the decomposition of the lactic acid.
ΔH°f of lactic acid is approximately -716.2 kJ
Reasons:
Known parameters are;
Mass of the lactic acid = 3.93 grams
Heat capacity of the bomb calorimeter = 10.80 kJ·K⁻¹
Change in temperature of the calorimeter, ΔT = 5.34 K
ΔHrxn = ΔErxn
ΔH°f of H₂O(l) = -285.8 kJ·mol⁻¹
ΔH°f of CO₂(g) = -393.5 kJ·mol⁻¹
The chemical equation for the reaction is presented as follows;
C₃H₆O₃ + 2O₂ → 3CO₂ + 3H₂OThe heat of the reaction = 10.80 kJ·K⁻¹ × 5.34 K = 57.672 kJ
Molar mass of C₃H₆O₃ = 90.07 g/mol
Number of moles of C₃H₆O₃ = [tex]\dfrac{3.93 \, g}{90.07 \, g/mol}[/tex] = 0.043633 moles
Number of moles of CO₂ produced = 3 × 0.043633 moles = 0.130899 moles
Heat produced = 0.130899 mole × -285.8 kJ·mol⁻¹ = -37.4109342 kJ
Moles of H₂O produced = 0.130899 moles
Heat produced = 0.130899 mole × -393.5 ≈ -51.51 kJ
Therefore, we have;
Heat absorbed by the lactic acid = ΔH°f of H₂O + ΔH°f of CO₂ + Heat absorbed by the calorimeter
Which gives;
Heat absorbed by lactic acid = -37.4109342 kJ - 51.51 kJ + 57.672 kJ ≈ -31.249 kJ
The heat absorbed by the lactic acid ≈ -31.249 kJ
[tex]\Delta H^{\circ}f \ of \ C_3H_6O_3 = \dfrac{-31.249}{0.043633} \approx -716.2[/tex]
ΔH°f of C₃H₆O₃ ≈ -716.2 kJ
Heat of formation of lactic acid ≈ -716.2 kJ.
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Related Questions
Protons and neutrons have opposite, but equal magnitude, charges. An atom contains the same number of protons and electrons Neutrons and electrons are found in the nucleus of an atom. Protons have about the same mass as electrons. Electrons make up most of the mass of an atom. which one is true about subatomic particles
Answers
Answer:
the true statement is an atom contains the same number of electron and protonExplanation:
let us see the behaviour of the sub atomic particles
nutrons and protons found in the nucleus of an atoman atom have the same number of electron and proton but they have different chargenutron is chargeless particlemost mass of the atom concentrated in the nucleus of an atomelectrons have almost 0 mass from an atommass of proton and mass of nutron are equvalent or almost equalthere are many properties of subatomic particles i have listed some of them above .
I think it is help ful for youWhat energy keeps the water cycle going?
Answers
Answer:
the the that keeps the water cycle going is heat
1. Oxygen was discovered by Joseph Priestley in 1774 when he heated mercury (II) oxide, HgO, to decompose it to form its constituent elements. How many moles of mercury (II) oxide are needed to produce 125 g of oxygen?
Given:
Unknown:
Mole ratio:
Solution:
2. In a blast furnace, iron (III) oxide is used to produce iron by the following (unbalanced) reaction:
Fe2O3(s) + CO(g) Fe(s) + CO2(g)
If 4000 g of Fe2O3 is available to react, how many moles of CO are needed?
Given:
Unknown:
Mole ratio:
Solution:
Final answer:
ugh pls help:(
Answers
Answer:
1. 7.81 moles HgO
2. n = mass/molar mass = (4000 g)/(159.69 g/mol) = 25.05 mol.
Explanation:
How many moles of mercury (II) oxide are needed to produce 125 g of oxygen?
2HgO ==> 2Hg + O2
125 g O2 x 1 mol O2/32 g x 2 mol HgO / mol O2 = 7.81 moles HgO
------------------------------------------------------------------------------------------------------------
If 4000 g of Fe2O3 is available to react, how many moles of CO are needed?
The no. of moles of CO are needed = 75.15 mol.
Fe₂O₃ + 3CO → 2Fe + 3CO₂,
It is clear that 1 mol of Fe₂O₃ reacts with 3 mol of CO to produce 2 mol of Fe and 3 mol of CO₂.
If 4.00 kg Fe₂O₃ are available to react, how many moles of CO are needed?
We need to calculate the no. of moles of 4.00 kg Fe₂O₃:
n = mass/molar mass = (4000 g)/(159.69 g/mol) = 25.05 mol.
Using cross multiplication:
1 mol of Fe₂O₃ need → 3 mol of CO to react completely, from stichiometry.
25.05 mol of Fe₂O₃ need → ??? mol of CO to react completely.
The no. of moles of CO are needed = (3 mol)(25.05 mol)/(1 mol) = 75.15 mol.
According to stoichiometry of the chemical equation, if 4000 g of iron oxide is available to react,25.04 moles of CO are needed.
What is chemical equation?Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.
A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .
The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.
159.69 g iron oxide gives 28 g CO thus 4000 g iron oxide will give 4000×28/159.69=701.35 g which is 701.35/28=25.04 moles.
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Write a balanced chemical equation based on the following description:
the reaction of gaseous tricarbon octahydride with oxygen gas produces gaseous carbon dioxide and water vapor
Answers
Answer:
C3H8(g) + 5O2(g) = 3CO2(g) + 4H2O(g)
Explanation:
Describe the difference between at atom and an ion in regards to their substaomic
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Answers
Answer:
difference between atom and ion
Explanation:
What is an Atom?
The smallest unit of matter. It is indivisible and consists of neutrons, electrons and protons. Atoms can take part in chemical reactions. Combination of atoms together forms molecule. Always the number of protons and electrons are equal. Independent life may or may not be feasible within a solution. Nucleus of the atom is formed by protons and neutrons. Surrounding the nucleus are the electrons.
What is an Ion?
Atoms where the electrons and protons are not equal are called ions. Ions are charged particles. They can be either positively charged ions or negatively charged ions. If an atom is charged electrically it is considered an ion. If an atom contains maximum number of electrons than protons, then it is called anion. If an atom contains maximum number of protons than electrons, then it is called cation. Independent existence in a solution. When an atom gains or loses electrons, ion is formed.
To make you understand how atom and ion are different from each other, here are the some major differences between atom and ion:
Why would you expect the materials used to make pot holders to be poor conductors of heat?
Answers
Answer:
Pot holders are meant to protect your hand from the heat of the pot, and so it would need to be a poor conductor of heat in order to do its job correctly. Silicon dioxide is a solid at room temperature and methanol is a liquid.
The electronic transition in a hydrogen atom from n = 6 to n = 3 emits electromagnetic radiation having a higher frequency than a transition
from n = 5 to n = 3
Answers
What mass of carbon dioxide is produced from the complete combustion of 4.60x10^-3g of methane?
Answers
Answer:
Explanation:
CH4 + 2O2 ==> CO2 + 2H2O
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Using the coefficients in the balanced equation, convert mols CH4 to mols CO2.
Now convert mols CO2 to grams. g = mols x molar mass.
Which of the following has more atoms?
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One mole of gold
One mole of silver
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Answers
Answer:
They all have the same number of atoms
Explanation:
Which of the following has more atoms?
One mole of zinc
One mole of gold
One mole of silver
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which has the greatest number of thing? a dozen eggs, a dozen cookies, a dozen pizzas?
a dozen is a number means 12
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particles.
just like every dozen contains 12
so
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Answers
Answer:
1-air
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Explanation:
If the atomic mass of an atom is 16 and its atomic number is 7. how many
neutrons does it have?
Answers
Answer:
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Explanation:
How do we find the atomic size of an atom?
Answers
Answer:
The size of an atom can be estimated by measuring the distance between adjacent atoms in a covalent compound. The covalent radius of a chlorine atom, for example, is half the distance between the nuclei of the atoms in a Cl2 molecule.
Why do you think dark surfaces absorb radiation better than light surfaces?
Answers
Your answer→ The lighter side absorbs less of the incident light, reflecting some of the energy. Darker materials also emit radiation more readily than light-colored materials, so they cool faster.
To solve this we must be knowing each and every concept related to radiation. Therefore, dark surfaces absorb radiation better than light surfaces as dark surfaces absorbs light of all wavelengths.
What is radiation?According to the energy of the emitted particles, radiation is frequently classified as being either ionizing or non-ionizing. More than 10 eV is often carried by ionizing radiation, which is sufficient to ionize atoms as well as molecules and rupture chemical bonds.
The word refers to radiation having an energy level high enough to ionize atoms, or to remove electrons from atoms to produce ions. Whenever an electron is removed from an atom's electron shell, or, as we may say, when it is "tried to knock out," the action of ionization takes place. Dark surfaces absorb radiation better than light surfaces as dark surfaces absorbs light of all wavelengths.
Therefore, dark surfaces absorb radiation better than light surfaces as dark surfaces absorbs light of all wavelengths.
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Substance whose smell changes in acidic or basic solutions
Answers
Answer:
Olfactory indicators
Explanation:
The substance whose odour changes in an acidic of basic medium are called olfactory indicators. In an olfactory indicator , smell varies depending on whether it is mixed with an acidic or basic solution.
Ribosome factory part or worker
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What is metabolism? I know the answer.
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Answer:
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Explanation:
1. ¿Cuál de los factores se deben emplear para convertir: a. ¿Número de moles de cloro en número de moles de NaCl? b. Moles de sodio a moles de cloro C. Moles de cloro a moles de sodio. 2 Na + CI, - 2 Naci
Ayudaaa
Answers
Answer:
Número de moles de cloro en número de moles de NaCl
Explanation:
espero que si sea la correcta
What is the angle between adjacent sp hybrid orbitals?
Answers
Answer:
180 degrees
Explanation:
sp hybridization generates orbitals that overlap linearly, generating a straight line. This leads to an angle measurement of 180 degrees.
The green light emitted by a stoplight has a wavelength of 505 nm. What is the frequency of this photon? (c = 3.00 × 10⁸ m/s).
Answers
Answer:
5.9405*10^14 Hz
Explanation:
Remember the equation c=v*λ
v=frequency
λ=wavelength
By manipulating the equation, we can get it in terms of frequency:
c/λ=v
Now convert wavelength to meters (1nm=m*10^-9)
5.05*10^-7m (2 decimal places were shifted to make the number between 1-10, hence the -7 exponent)
Use the manipulated equation:
(3.00*10^8)/(5.05*10^-7), which yields:
5.9405*10^14 Hz (or s^-1)
The frequency of the photon will be "[tex]5.9405\times 10^{14} \ Hz[/tex]".
According to the question,
Wavelength,
[tex]\lambda = 505 \ nm[/tex]or,
[tex]= 5.05\times 10^{-7} \ m[/tex]
As we know the equation,
→ [tex]c = v\times \lambda[/tex]
or,
→ [tex]v = \frac{c}{\lambda}[/tex]
By putting the values, we get
[tex]= \frac{3.00\times 10^8}{5.05\times 10^{-7}}[/tex]
[tex]= 5.9405\times 10^{14} \ Hz[/tex]
Thus the above answer is right.
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Give one example of a question that science could test. Then, explain in your own words why it is an example of a scientific question. Please!
Answers
Answer:
Questions are an essential part of science. ... They state the final question in a way that can be answered by investigation or experiment. A good scientific question is: “What effect does the pH of water have on radish seed germination?” Good scientific questions are defined, measurable, and controllable.
Vitamin D is produced in the skin when 7-dehydrocholesterol reacts with UVB rays (ultraviolet B) having wavelengths between
270 nm and 300 nm. What is the energy range Emin < E< Emax of the UVB photons?
Answers
The energy range expected is 6.6 × 10^-19 J < E < 7.33 × 10^-19 J
The energy of the photon is given by;
E = hc/λ
E = energy of the photon
h = Plank's constant
c = speed of light
λ = wavelength of light
For the upper boundary range;
E = ?
h = 6.6 × 10^-34 Js
c = 3 × 10^8 m/s
λ = 270 × 10^-9
E = 6.6 × 10^-34 Js × 3 × 10^8 m/s / 270 × 10^-9
E = 7.33 × 10^-19 J
For the lower range;
E = ?
h = 6.6 × 10^-34 Js
c = 3 × 10^8 m/s
λ =300 × 10^-9
E = 6.6 × 10^-34 Js × 3 × 10^8 m/s / 300 × 10^-9
E = 6.6 × 10^-19 J
Hence, the energy range 6.6 × 10^-19 J < E < 7.33 × 10^-19 J
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Which describes a chemical change? (Select all that apply.)
A new substance is created.
A phase change is occurring.
It is a permanent change.
It can be a physical change.
Answers
Explanation:
it is a permanent change
Answer: It is a permenat change
Explanation: Because you are creating it into something else and when it turns into that thing it stays like that permanatly.
state why vulcanologist make predications about when a volcano will erupt
Answers
Answer:
They want to know how long it has been since it last erupted.
Explanation:
Scientists study a volcano's history to try to predict when it will next erupt. They also want to know the time span between its previous eruptions
In order for a light bulb to be turned on in a circuit, it must have what kind of switch?
Answers
Answer:
Both switches must be closed in order for the circuit to be complete and for the bulb to light. (This would indicate the 'armed' status of this burglar alarm.) Magnetic switches come in 2 varieties - "Normally Closed" and "Normally Open". These 2 terms describe the state of the switch when it is NOT being controlled by the magnet.
Explanation:
How many grams are in 0.990 mol of neon?
mass in grams:
Answers
Explanation:
Multiply the given moles times the molar mass of neon, 20.180 g/mol (periodic table).
Answer:
Multiply the supplied moles by 20.180 g/mol, the molar mass of neon (periodic table).
Explanation:
adjoa's gross salary for last month was ghs 4687.24. if ghs 421.78 was deducted from adjoa's salary pay,how much take home pay did adjoa earned this past month?
Answers
Since Ghs. 421.78 was deducted from Adjoa's salary pay, her take home pay is Ghs. 4265.46.
Given the following data:
Adjoa's gross salary = Ghs. 4687.24.Deduction = Ghs. 421.78Gross profit can be defined as the profit earned by a business after subtracting its cost of manufacturing and distributing goods from its total revenue (sales).
On a related note, gross salary is the amount of money earned by an individual before any deduction such as tax.
To find how much take home pay Adjoa earned this past month:
[tex]Take\;home = Gross\;salary - deduction\\\\Take\;home = 4687.24 - 421.78[/tex]
Take home = Ghs. 4265.46.
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Nguyên tử khối của đồng
Answers
Answer:
huwattt
Explanation:
i can't understand
detailed description of how group 1 atoms bond with group 7 atoms
Answers
Answer:
group 7 atoms react
Explanation:
When a group 7 element takes part in a reaction, its atoms each gain one electron. These atoms form negatively charged ions . The ions have a stable arrangement of electrons, with a complete outer shell.
What is the name of the ion with 4 neutrons and 4 electrons with a 1- charge?
A: Hydrogen
B: Berrylium
C: Lithium
D: Helium
Answers
Answer:
C.
Explanation:
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Identify which of the following equations are balanced and which ones are not balanced
A. CH4 +202 —> CO2 + 2H20
B. 6CO2 + 6H2O—> C6H12O6+602
C. 2Na + H2O —> 2NaOH+ H2
Answers
Answer:
A. balancedB. UnblalancedC. UnbalancedExplanation:
