Consider the following reaction at 283 K:
A
+
B
â
C
+
D
where rate = k
[
A
]
[
B
]
. An experiment was performed where [
A
]
0
=
2.87
M and [
B
]
0
=
0.00239
M. A plot of ln
[
B
]
vs. time has a slope of -0.1469. What will the rate of this reaction be when [
A
]
=
[
B
]
=
0.713
M?
Answers
The rate of the reaction when [A] = [B] = 0.713 M will be approximately 0.0259 M/s.
To determine the rate of the reaction when [A] = [B] = 0.713 M, we need to consider the given information and follow these steps:
1. Given the rate law: rate = k[A][B].
2. We know the initial concentrations: [A]0 = 2.87 M and [B]0 = 0.00239 M.
3. We're given a plot of ln[B] vs. time with a slope of -0.1469.
Now, we will first find the rate constant k:
4. The slope of the plot, -0.1469, equals the negative value of k multiplied by [A]0.
5. So, k = -(-0.1469) / 2.87 = 0.0512.
Next, we will calculate the rate when [A] = [B] = 0.713 M:
6. Plug in the values into the rate law: rate = k[A][B].
7. rate = 0.0512 * 0.713 * 0.713.
Thus, the rate of the reaction when [A] = [B] = 0.713 M will be approximately 0.0259 M/s.
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Related Questions
What is the density of a glass fragment that has a mass of 1.5g and a volume of 0.75mL?
Answers
2gcm³ is the density of a glass fragment that has a mass of 1.5g and a volume of 0.75mL.
What is density ?The term density is define as the ratio of mass and volume. The formula for density is d = M/V, where d is density, M is mass, and V is volume. Density is commonly expressed in units of grams per cubic centimeter.
Density = mass / volume
Given:
Density = ?
Mass = 1.5 gram
Volume = 0.75 ml
By substituting this values in give equation we get,
Density = 1.5 / 0.75
= 2 gcm³
Thus, 2 gcm³ is the density of a glass fragment that has a mass of 1.5g and a volume of 0.75mL.
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Nitric acid, hno3(aq), is commercially available as a 33. 7 m aqueous solution (density = 1. 35 g/ml). what is the molarity of this solution?
Answers
The molarity of the nitric acid solution is approximately 21.44 M.
To find the molarity of the nitric acid solution, we need to use the formula:
Molarity (M) = moles of solute / volume of solution (in liters)
First, we need to determine the moles of nitric acid in the solution. To do this, we'll use the equation:
moles = mass / molar mass
The molar mass of HNO₃ is calculated as follows:
H = 1.01 g/mol
N = 14.01 g/mol
O = 16.00 g/mol (x3, as there are three oxygen atoms in HNO₃)
Molar mass of HNO₃ = 1.01 + 14.01 + (16.00 × 3) = 63.01 g/mol
Next, we'll calculate the mass of the nitric acid in the solution:
mass = volume × density
Given density = 1.35 g/mL and volume = 33.7 mL, we can calculate the mass as follows:
mass = 33.7 mL × 1.35 g/mL = 45.495 g
Now, we can calculate the moles of nitric acid:
moles = 45.495 g / 63.01 g/mol ≈ 0.722 mol
Finally, we can calculate the molarity using the moles of nitric acid and the volume of the solution in liters:
Molarity = 0.722 mol / (33.7 mL / 1000) L ≈ 21.44 M
Therefore, the molarity of the nitric acid solution is approximately 21.44 M.
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Chalk is a silicate carbonate evaporite sandstone QUESTION 33 a photosyntehtic creature with a silica shell can be a O coccolithophorid foraminifer diatom radiolarian QUESTION 34 recrystallization of chalk at the ocean bottom (not in metamorphic conditions) can give us O micrite chert marble quartzite
Answers
Diatoms are single-celled algae that have a silica (silicate) shell called a frustule.
Diatoms are photosynthetic organisms and are known for their intricate and diverse shapes. Diatoms are commonly found in freshwater and marine environments and play a significant role in the global carbon cycle.
Micrite is a fine-grained carbonate sedimentary rock composed of tiny carbonate particles. It forms through the precipitation and accumulation of carbonate minerals, such as calcite or aragonite, in marine environments. In the case of chalk, which is primarily composed of microscopic fragments of calcium carbonate from marine organisms, recrystallization can occur at the ocean bottom under specific conditions, leading to the formation of micrites.
Therefore, it's important to note that chert, marble, and quartzite are not the typical products of recrystallization of chalk at the ocean bottom.
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Calculate the decrease in temperature when 8.5 Lat 25.0 °C is compressed to 4.00 L.
Answers
The decrease in temperature of a gas when compressed can be calculated using the ideal gas law, which relates the pressure, volume, temperature, and number of particles of a gas.
The ideal gas law is expressed as PV = nRT, where P is the pressure, V is the volume, n is the number of particles, R is the gas constant, and T is the temperature.
To calculate the decrease in temperature, we first need to determine the initial conditions of the gas. At 8.5 L and 25.0 °C, we can assume that the pressure is constant and that the number of particles is also constant. Therefore, we can write:
P1V1/T1 = P2V2/T2
where P1 is the initial pressure, V1 is the initial volume, T1 is the initial temperature, P2 is the final pressure, V2 is the final volume, and T2 is the final temperature.
Plugging in the values, we get:
P1 × 8.5 L / 25.0 °C = P2 × 4.00 L / T2
Simplifying and solving for T2, we get:
T2 = (P2 × 4.00 L × 25.0 °C) / (P1 × 8.5 L)
Assuming that the pressure remains constant, we can simplify the equation further:
T2 = (4.00 L × 25.0 °C) / 8.5 L
T2 = 11.8 °C
Therefore, the decrease in temperature is:
25.0 °C - 11.8 °C = 13.2 °C
In summary, when 8.5 L of gas at 25.0 °C is compressed to 4.00 L, the temperature decreases by 13.2 °C.
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yoooo help me w this one
Answers
Answer:
0.84kg of gatorade powder
Explanation:
From the question given, we were told that 0.6kg of gatorade powder required 5 gallons of water.
To obtain the mass of gatorade needed for 7 gallons of water, we simply do the following:
0.6kg of gatorade powder required 5 gallons of water.
Therefore, xkg of gatorade powder will require 7 gallons of water i.e
xkg of gatorade powder = (0.6 x 7)/5
xkg of gatorade powder = 0.84kg
Therefore, 0.84kg of gatorade powder will be required.
How many moles are in 5.025 grams of NaOH?
Answers
Answer:
The SI base unit for amount of substance is the mole. 1 grams NaOH is equal to 0.025001806380511 mole.
Answer:
0.025001806380511 mole.
Explanation:
The SI base unit for amount of substance is the mole. 1 grams NaOH is equal to 0.025001806380511 mole.
what key absorbance indicative of starting material 2-methylcyclohexanone should be absent? give wavenumber, bond type and functional group.
Answers
The key absorbance indicative of starting material 2-methyl cyclohexanone that should be absent is the carbonyl stretch at around \(1710-1735 cm^{-1}.\) , the bond type is C=O and the functional group is Ketone.
Infrared spectroscopy is a useful technique in identifying functional groups in organic compounds. The carbonyl stretch, which is typically found at 1710-1735 cm^-1, is a characteristic absorption band for ketones and aldehydes. Since 2-methyl cyclohexanone is a ketone, it should exhibit this absorption band in its infrared spectrum.
However, if this band is absent in the spectrum, it suggests that the compound has undergone a chemical reaction and the carbonyl functional group has been transformed into a different functional group. The absence of the carbonyl stretch at around 1710-1735 cm⁻¹ is indicative of the absence of the starting material, 2-methyl cyclohexanone.
This peak is characteristic of the C=O bond stretch in a ketone functional group. In 2-methyl cyclohexanone, this bond is present in the starting material but absent in the product after the reaction.
The bond type and functional group of this key absorbance are:
Bond type: C=O bond
Functional group: Ketone (C=O group attached to two alkyl or aryl groups)
By observing the absence of this peak in the IR spectrum of the product, we can confirm that the reaction has taken place and the starting material has been consumed. This technique is commonly used in organic chemistry to monitor the progress of reactions and determine the identity of products.
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If I have an object with a density of 2.42 g/mL and a mass of 27 g, what is the volume, in mL ?
Answers
an aqueous solution of ca(oh)2 with a ph of 14.235 is prepared in a 500.00 ml volumetric flask by adding 91.138 ml of a ca(oh)2 stock solution. what is the concentration of the ca(oh)2 stock solution (units are m)?
Answers
The concentration of the Ca(OH)₂ stock solution is 0.00511 M.
The pH of an aqueous solution of Ca(OH)₂ can be calculated using the following equation,
pH = 14 - log([Ca(OH)₂])
where [Ca(OH)₂] is the concentration of Ca(OH)₂ in moles per liter (M).
Since the solution has a pH of 14.235, we can plug this value into the equation and solve for [Ca(OH)₂]:
14.235 = 14 - log([Ca(OH)₂])
log([Ca(OH)₂]) = 14 - 14.235 = -0.235
[Ca(OH)₂] = 10^(-0.235) = 0.00513 M
The Ca(OH)₂ stock solution was diluted to a final volume of 500.00 ml by adding 91.138 ml of the stock solution to a volumetric flask and filling up to the mark with water. Therefore, the number of moles of Ca(OH)₂ in the stock solution can be calculated as:
moles of Ca(OH)₂ = concentration × volume = [Ca(OH)₂] × (91.138/1000) = 0.000467 moles
The stock solution was diluted to a final volume of 500.00 ml, so the final concentration of the Ca(OH)₂ solution is:
final concentration = moles / volume = 0.000467 moles / 0.500 L = 0.000934 M
Therefore, the concentration of the Ca(OH)₂ stock solution is:
concentration = final concentration × (final volume / initial volume) = 0.000934 M × (500.00 ml / 91.138 ml) = 0.00511 M
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The phosphorous, P2O5, in a 47. 683 g sample of plant food was converted to PO4 3- through a hydrolysis reaction and then precipitated as Ag3PO4 through the addition of 50. 00 mL of 0. 9205 M AgNO3. The excess AgNO3 was back-titrated with 16. 24 mL of 0. 2007 M KSCN. From this information determine the wt% P2O5 in the plant food sample
Answers
The weight percent of P₂O₅ in the plant food sample is 11.49%.
The molar mass of P₂O₅ is 141.94 g/mol, and the molar mass of Ag₃PO₄ is 418.58 g/mol.
First, we need to calculate the number of moles of AgNO₃ used,
0.05000 L x 0.9205 mol/L = 0.046025 mol AgNO₃
Since Ag₃PO₄ forms a 1:1 stoichiometric ratio with AgNO₃, the number of moles of Ag₃PO₄ formed is also 0.046025 mol.
Next, we can calculate the mass of Ag₃PO₄ formed,
0.046025 mol Ag₃PO₄ x 418.58 g/mol = 19.271 g Ag₃PO₄
Since the phosphorus in the plant food sample was converted to Ag₃PO₄, the mass of P₂O₅ in the sample can be calculated from the mass of Ag₃PO₄ formed using the molar mass ratio,
19.271 g Ag₃PO₄ x (2 mol P₂O₅ / 1 mol Ag₃PO₄) x (141.94 g/mol) = 5.474 g P₂O₅
Therefore, the weight percent of P₂O₅ in the plant food sample can be calculated as,
(5.474 g P₂O₅ / 47.683 g sample) x 100% = 11.49% P₂O₅
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What volume would 56.2 mL of gas at 820 mm of Hg occupy at 720 mm of Hg?
Answers
Answer:
49.35 mL
Explanation:
Given: 56.2 mL of gas
To find: volume that 56.2 mL of gas at 820 mm of Hg would occupy at 720 mm of Hg
Solution:
At 820 mm of Hg, volume of gas is 56.2 mL
At 1 mm of Hg, volume of gas is \(\frac{56.2}{820}\)
At 720 mm of Hg, volume of gas is \(\frac{56.2}{820}(720)=49.35\,\,mL\)
element x has two naturally occurring isotopes, 65x (isotopic mass 65.1012 amu , abundance 39.25% ) and 67x (isotopic mass 67.0782 amu , abundance 60.75% ). calculate the atomic mass of element x.
Answers
The atomic mass of element X, given that it has two naturally occurring isotopes of ⁶⁵X and X⁶⁷ is 66.3022 amu
How do i determine the atomic mass of element X?First, we shall list out the given parameters from the question. This is shown below:
Mass of 1st isotope, ⁶⁵X = 65.1012 amuAbundance of 1st isotope, ⁶⁵X (1st%) = 39.25%Mass of 2nd isotope, X⁶⁷ = 67.0782 amuAbundance of 2nd isotope, X⁶⁷ (2nd%) = 60.75%Atomic mass of element X=?The atomic mass of the element X can be obtain as follow:
Atomic mass = [(Mass of 1st × 1st%) / 100] + [(Mass of 2nd × 2nd%) / 100]
Atomic mass = [(65.1012 × 39.25) / 100] + [(67.0782 × 60.75) / 100]
Atomic mass = 25.5522 + 40.7500
Atomic mass = 66.3022 amu
Thus, we can conclude that the atomic mass of element X is 66.3022 amu
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The triiodide ion (13.) has the iodine atoms arranged in a line, not a ring. This ion is stable, but the F3-ion is not. Why? O a. fluorine atoms are too large to form this ion. O b. this structure requires unpaired electrons, which are more stable on heavier atoms O c. fluorine atoms are too small to form this ion. d. the triiodide ion has a trigonal bipyramidal electron geometry, but with three lone pairs, resulting in a linear molecular geometry: to do this, the molecule requires an expanded valence shell; period two elements cannot do this. e. fluorine is not electronegative enough to want to make an anion.
Answers
The correct answer is d. The triiodide ion is stable due to its expanded valence shell, which period two elements like fluorine cannot accommodate.
The triiodide ion (I₃⁻) has a trigonal bipyramidal electron geometry but with three lone pairs, which results in a linear molecular geometry. This structure is possible because iodine can have an expanded valence shell, allowing it to accommodate more than eight electrons. Fluorine, being a period two element, cannot have an expanded valence shell and thus, cannot form a stable F₃⁻ ion.
Options a, b, c, and e are incorrect because they do not accurately describe the reason for the stability difference between the triiodide ion and the F₃⁻ ion. The key factor is the expanded valence shell capability of iodine, which fluorine lacks.
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which of the following is not true of hydrogen?
it can form an ion with a +1charge
It can form an ion with a -1 charge.
It is usually found as free hydrogen and not combined with other elements.
It is a colorless, odorless gas.
Answers
At what temperature will the volume of a gas be a, halved b, doubled c, tripled at constant pressure if the original temperature is 17 degree celsius
Answers
Recall Charles law
volume of a gas is directly proportional to temperatureSo
#a
Volume is halved means Temperature is halved
T=17/2T=8.5°C#b
Volume is doubled means temperature is doubled
T=2(17)T=34°C#c
Volume is tripled means temperature is trippled
T=3(17)T=51°CAnswer:
8.5 °C34 °C51 °CExplanation:
The relation between temperature and volume at constant pressure is given by Charles Law.
Scenario 1 : Volume is halved
⇒ Let initial volume be V
⇒ \(\frac{V}{17} = \frac{0.5V}{T}\)
⇒ T = 17 × 0.5
⇒ T = 8.5 °C
Scenario 2 : Volume is doubled
⇒ \(\frac{V}{17} = \frac{2V}{T}\)
⇒ T = 17 × 2
⇒ T = 34 °C
Scenario 3 : Volume is tripled
⇒ \(\frac{V}{17} = \frac{3V}{T}\)
⇒ T = 17 × 3
⇒ T = 51 °C
Introduction to atoms) How do I do this
Answers
Answer:
and the answers are
1 electron cloud
2 neutron
3 no charge
4 electron shell
5 proton
6 + charge
7 nucleus
8 neutron
9 - charge
Explanation:
PLEASE GIVE BRAINLIST
how many moles of water are in 0.340 g of water?
Answers
Answer: 0.018 recurring?
Explanation:
moles = mass/mr
H20 = 2 + 16 = 18
0.340/18 = 0.018
Es un cambio natural o provocado, donde se produce energía para agua y dióxido de carbono: a)Precipitación. b)Fermentación c) Efervecencia. d) Combustión.
Answers
Answer:
d) Combustión.
Explanation:
¡Hola!
En este caso, dado que estamos enfocados en el concepto de cambio químico, el cual se caracteriza por exhibir un cambio en la composición e identidad de las sustancias iniciales (reactivos) a otras finales (productos).
Ahora bien, como se nos dice que los productos de este cambio químico son energía, agua y dióxido de carbono, inferimos que el nombre de este proceso es d) Combustión, por ejemplo la combustion del gas natural para calentar nuestras comidas en la cocina.
¡Saludos!
How many moles are present in 34 grams of Cu(OH)2? Show How you got the Answer
Answers
Answer:
0.347
Explanation:
moles= mass/molecular mass
moles= 34/64+(16×2)+(1×2)
moles=34/98
= 0.347 (3.s.f)
PLEASE HELP!! WILL GIVE BRAINLIEST!!! I NEED ANSWER QUICKLY!!!
Check the correct box to describe the periodic trends in electronegativity.
Electronegativity across a period:
decreases.
increases.
Electronegativity down a group:
decreases.
increases.
Answers
Electronegativity across a period: increases.
Electronegativity down a group: decreases.
Explanation:
Just did on Edge 2021
Electronegativity across a period increases and Electronegativity down a group decreases.
What is Electronegativity ?Electronegativity, symbolized as χ, is the tendency for an atom of a given chemical element to attract shared electrons when forming a chemical bond.
An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus.
On the periodic table, electronegativity generally increases as we move from left to right across a period and decreases as you move down a group.
As a result, the most electronegative elements are found on the top right of the periodic table, while the least electronegative elements are found on the bottom left.
Hence, Electronegativity across a period increases and Electronegativity down a group decreases.
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A mixture of oxygen( O2), dinitrogen monoxide (N2O), and argon (Ar) has a total pressure of 0.98 atm. What is the partial pressure of N2O, if the partial pressure of O2 is 0.48 atm and the partial pressure of Ar is 0.15 atm?
Answers
Answer: The partial pressure of \(N_{2}O\) is 0.35 atm.
Explanation:
Given: Total pressure = 0.98 atm
Partial pressure of \(O_{2}\) = 0.48 atm
Partial pressure of Ar = 0.15 atm
Partial pressure of \(N_{2}O\) = ?
Total pressure is the sum of partial pressure of each component present in a mixture of gases.
Hence, partial pressure of \(N_{2}O\) is calculated as follows.
Total pressure = \(P_{N_{2}O} + P_{O_{2}} + P_{Ar}\)
Substitute the values into above formula as follows.
\(Total pressure = P_{N_{2}O} + P_{O_{2}} + P_{Ar}\\0.98 atm = P_{N_{2}O} + 0.48 atm + 0.15 atm\\P_{N_{2}O} = 0.35 atm\)
Thus, we can conclude that the partial pressure of \(N_{2}O\) is 0.35 atm.
Name an element that has the same physical and chemical properties as Fluorine (F)
Answers
how much energy does it take to heat 4.0 moles of a monoatomic ideal gas from 20.0 0c to 100 0c at constant volume?
Answers
The energy required to heat 4.0 moles of a monoatomic ideal gas from 20.0 °C to 100 °C at constant volume is approximately 1997.2 Joules.
To calculate the energy required to heat a monoatomic ideal gas, we can use the equation:
Q = n * Cv * ΔT,
where Q is the energy, n is the number of moles of gas, Cv is the molar specific heat at constant volume, and ΔT is the change in temperature.
First, we need to find the molar specific heat at constant volume for a monoatomic ideal gas. The molar specific heat at constant volume (Cv) for a monoatomic ideal gas is given by:
Cv = (3/2)R,
where R is the ideal gas constant.
Next, we can calculate the change in temperature (ΔT):
ΔT = T2 - T1,
where T2 is the final temperature (100 °C) and T1 is the initial temperature (20 °C). The ideal gas constant R is approximately 8.314 J/(mol·K).
Substituting the values into the equation, we have:
Q = 4.0 mol * (3/2)R * (100 °C - 20 °C).
Q = 4.0 mol * (3/2) * R * 80 °C.
Q = 4.0 mol * (3/2) * 8.314 J/(mol·K) * 80 °C.
Q ≈ 1997.2 J.
Therefore, the energy required to heat 4.0 moles of a monoatomic ideal gas from 20.0 °C to 100 °C at constant volume is approximately 1997.2 Joules.
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Chris' yard has a light brown soil that is very fine. Chris has a hard time finding any rocks, including pebbles, in his yard. Reese's yard has a gray soil that is full of small and medium size rocks. If it rained on both of Chris' and Reese's yards, which yard would likely hold the water above ground the longest? A. Both yards would absorb the water at the same rate. B. Reese's yard C. Chris' yard D. Neither yard would absorb any water.
Answers
Answer:
B. Reese's yard
Explanation:
Because Reese's yard is full of rocks, rock's don't absorb water, while Chris' yard is only soil, which will make his yard absorb water quicker.
Which of these is NOT a neutralisation reaction?
Answers
Answer:
Magnesium + hydrochloric acid → magnesium chloride + hydrogen
why? because the product of a neutralization reaction are always a salt and water. This reaction is the only one which does not have water as a product, so it is not neutralization.
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explain what a transfer of energy is and give an example.
Answers
Explanation:
Energy transfer is the movement of energy from one location to another. For example, when electricity moves from a wall plug, through a charger, to a battery. ...
Which is a chemical property of hydrogen?
A.
It is a light gas.
B.
It is a combustible gas.
C.
It is a colorless gas.
D.
It has a boiling point of -252.87°C.
E.
It is a good conductor of electricity.
Answers
Answer:
CExplanation:
It is a colorlessI hope you help by my answee
2. you have 0.05 ml of an undiluted culture at a concentration of 3.6 x 106 cfu/ml. you then add 4.95 ml of sterile water. what is the dilution, and what is the final concentration of cells?
Answers
The final concentration of cells in the diluted culture is 3.6 x 108 cfu/ml
ProcessTo calculate the final concentration, the formula was used
V1 . C1 = V2. C2
Where
V1 = initial volume
C1 = initial concentration
V2 = final volume
C2 = final concentration
Calculation of the final concentrationV1 . C1 = V2. C2
Clearing C2 we get
C2 = V1 . C1/V2
Data
V1 = 0.05ml
C1 = 3.6 x 10∧6 cfu/ml
V2 = 0.05ml + 4.95ml = 5ml
Subsequently, the data is replaced in the formula
C2 = V1 . C1/V2
C2 = 0.05 . 3.6 x 10∧6 / 5ml
C2 = 3.6 x 10∧8 cfu/ml
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It's actually Science but I didn't find it.
Word Bank: friction, gravity, equal, motion, balanced, unbalanced, change, changing, direction speed
Forces acting on an object are balanced or unbalanced. Forces acting on an object have _____ strength and act in opposite directions they are ______ . These forces cancel each other, and _____ of the object does not _____ . When the Forces acting on an object are, _____ they do not cancel out another. An unbalanced force on an object results on the object's motion _____ . The object may change its _____ (speed up or slow down), or it may change its _____ . _______ is a force that resists the motion or the tendency toward motion between two objects in contact with each other. _____ is a force that pulls objects toward one another. For example, Earth pulls all objects toward it.
Someone please help me
Answers
Answer:
Forces acting on an object may be balanced or unbalanced. When the forces acting on an object have equal strength and act in opposite directions, they are balanced. These forces cancel out one another, and the motion of the object does not change. When the forces acting on an object are unbalanced, they do not cancel out one another. An unbalanced force acting on an object results in the object’s motion changing. The object may change its speed (speed up or slow down), or it may change its direction. Friction is a force that resists the motion or the tendency toward motion between two objects in contact with each other. Gravity is a force that pulls objects toward one another. For example, Earth pulls all objects toward it.
Explanation:
Calculate the enthalpy change for the reaction: 4Al(s) + 3MnO2(s) --> 2Al2O3 (s) + 3Mn(s)2Al(s) + 3/2 O2 (g) --> Al2O3(s). ∆ H=-1676.0 kJMn(s) + O2 (g) --> MnO2(s). ∆ H = -521.0 kJ
Answers
Explanation:
To solve this question, we need to use the Hess's Law.
Hess's Law states that: in a chemical reaction, the heat released or absorbed is constant and independent of the number of steps the reaction goes through. That is, the law states that the enthalpy change of a chemical reaction depends only on its initial state and its final state.
Hess's Law is also known as the law of the sum of heats of reaction, because the enthalpy change is equal to the sum of the changes in the steps through which the chemical reaction passes (intermediate reactions). The calculation is performed as follows:
- If the chemical reaction is inverted, the sign of the enthalpy change must also be inverted;
- If the equation is multiplied, the enthalpy change must also be multiplied;
- If dividing the equation, the enthalpy change must also be divided.
So we're going to invert, divide, or multiply each given equation in order to get the equation that the question gives us.
The equation the question gives us is:
4Al(s) + 3MnO2(s) --> 2Al2O3 (s) + 3Mn(s)
Let's multiply the first equation by 2:
4 Al + 3 O2 --> 2 Al2O3
ΔH = -1676 * 2 = -3,352 kJ
Let's invert and multiply by 3 the second equation:
3 MnO2 -> 3 Mn + 3O2
ΔH = -521 * 3 * (-1)
ΔH = 1,563 kJ
Answer: -1,789 kJ
