Question 11 of 30
During a reaction, the enthalpy of formation of an intermediate is -286
kJ/mol. During the reaction, 2 moles of the intermediate are produced. What
is the enthalpy value for this step of the reaction?
O A. -286 kJ
B. 572 kJ
OC. 286 kJ
OD. -572 kJ
By convention, the standard enthalpy of formation of all elements in their standard states are assumed to be zero. Here the enthalpy value for the intermediate formation step is -572 kJ. The correct option is D.
What is enthalpy of formation?The standard enthalpy of formation of a compound is defined as the enthalpy change accompanying the formation of one mole of the compound from its constituent elements, all the substances being in their standard states.
The symbol used to represent the standard enthalpy of formation is ΔfH⁰. The knowledge of standard enthalpies of various substances is useful for calculating the standard enthalpies of a reaction.
The overall energy difference between the reactants and products remains the same no matter how many intermediates there are in the reaction pathway.
The enthalpy value = 2 × -286 = -572 kJ
Thus the correct option is D.
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Which of these is a benefit of including comments in your code
makes the app run faster
O helps other programmers understand your code
O improves the user interface
O makes your app more user friendly
A benefit of including comments in your code is that it helps other programmers understand your code.
What is a Code?These are numbers and letters which are used to identify a particular thing at a point in time.
Comments can be put in a code so as to enable others know and understand real intentions about it etc.
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Answer: O helps other programmers understand your code
Explanation: got it right on edgen
Question 1 (1 point)
Using the graph from the article, which air pollutant caused a change in bird abundance?
Question 1 options:
tropospheric ozone (O3)
fine particulates (PM 2.5)
Answer:
Di ko na po matandaan yung answer ko Jan kasi
nakalimutan ko po sorry talaga
Explanation:
Which term is used to describe all the habitats around the world?
Ecosystem diversity
Genetic diversity
Natural selection
Species diversity
Answer:
ecosystem diversity
Explanation:
hope this helped
How many grams do 6.534e+24 molecules of phosphoric acid weigh?
Answer:
1,063 grams H₃PO₄
Explanation:
To find the mass of phosphoric acid (H₃PO₄), you should (1) convert molecules to moles (via Avogadro's number) and then (2) convert moles to grams (via molar mass from periodic table).
Molar Mass (H₃PO₄): 3(1.008 g/mol) + 30.974 g/mol + 4(15.998 g/mol)
Molar Mas (H₃PO₄): 97.99 g/mol
6.534 x 10²⁴ molecules H₃PO₄ 1 mole 97.99 g
--------------------------------------------- x ------------------------------------- x --------------
6.022 x 10²³ molecules 1 mole
= 1,063 grams H₃PO₄
the density of 190mg of a liquid is 0.0076g/cm calculate the volume in ml
[tex]\\ \rm\Rrightarrow Density=\dfrac{Mass}{Volume}[/tex]
[tex]\\ \rm\Rrightarrow Volume=\dfrac{Mass}{Density}[/tex]
[tex]\\ \rm\Rrightarrow Volume=\dfrac{0.19}{0.0076}[/tex]
[tex]\\ \rm\Rrightarrow Volume=25cm³[/tex]
[tex]\\ \rm\Rrightarrow Volume=25mL[/tex]
URGENT HELP NEEDED!!! SPACE
Record your observation statements from Space Academy.
When the mass of the sun is larger, Earth moves around the sun at a faster (faster, slower) pace.
When the mass of the sun is smaller, Earth moves around the sun at a slower (faster, slower) pace.
When Earth is closer to the sun, its orbit becomes faster (faster, slower).
When Earth is farther from the sun, its orbit becomes slower (faster, slower).
For each trial, record the orbit number of each planet from the sun. Be sure to indicate the number of planets in the habitable zone after each trial. Create a different configuration of planets for each trial. An example has been supplied for you.
Orbit Number
Planet One Orbit Number
Planet Two Orbit Number
Planet Three Orbit Number
Planet Four Number of planets in the habitable zone Number of planets left in successful orbit
Example: sun's mass 1x
1
3
5
6
1
2
sun's mass 1x—Trial One
1
5
2
3
1
1
sun's mass 1x—Trial Two
1
2
0
0
2
2
sun's mass 2x—Trial One
1
0
0
0
1
0
sun's mass 2x—Trial Two
1
3
2
0
4
0
sun's mass 3x—Trial One
1
2
0
0
2
0
sun's mass 3x—Trial Two
1
0
0
0
1
3
Conclusion:
Your conclusion will include a summary of the lab results and an interpretation of the results. Please answer all questions in complete sentences using your own words.
Using two to three sentences, summarize what you investigated and observed in this lab.
You completed three terra forming trials. Describe the how the sun's mass affects planets in a solar system. Use data you recorded to support your conclusions.
In this simulation, the masses of the planets were all the same. Do you think if the masses of the planets were different, it would affect the results? Why or why not?
How does this simulation demonstrate the law of universal gravitation?
It is the year 2085, and the world population has grown at an alarming rate. As a space explorer, you have been sent on a terraforming mission into space. Your mission to search for a habitable planet for humans to colonize in addition to planet Earth. You found a planet you believe would be habitable, and now need to report back your findings. Describe the new planet, and why it would be perfect for maintaining human life.
The new planet is suitable for human life because it is similar to planet earth.
Describe the new planet, and why it would be perfect for maintaining human life?
The new planet has similar atmosphere just like the earth's atmosphere. It has large amount of vegetation that can hold large amount of animals. It is suitable for growing for different crops that provide food to humans.
So we can conclude that the new planet is suitable for human life because it is similar to planet earth.
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Part E
Tsunami evacuation plans often consider the elevation of the community and its distance from the shoreline when
deciding which towns to evacuate. How could this data help in building new homes and communities along coastal areas
that are prone to tsunamis?
Answer:
make the house elevated
A solution of the ionic salt
NaCI would have
pH.
an acidic
a basic
a neutral
Answer:
Neutral
Explanation:
NaCl aqueous solution is formed by NaOH and HCl.
NaOH is a base and HCl is an acid, so they go through neutralization process forming a neutral salt and water.
with strong heating calcium carbonate undergoes thermal decomposition how many mole of CaCO3 are there in 50g of calcium carbonate
Answer:
a)CaCO 3→CaO+CO 2CaCO3→CaO+CO2
b) Moles of CaCO3=4.37moles
c) I) Mass of calcium oxide =28g
ii)Mass of carbon dioxide=16.7g
iii)Volume=203cm3
Which scientist performed the cathode ray experiment leading to the discovery of electrons
The scientist that performed the cathode ray experiment leading to the discovery of electrons is J.J. Thomson.
What is a cathode ray?A cathode ray is a tube that contains negatively charged electrode( that is the cathode) which emits electrons when heated at a low pressure.
The cathode ray was used by the scientist, J.J. Thomson to find the ratio of charge to mass (e/m) of the electrons.
Therefore, the scientist that performed the cathode ray experiment leading to the discovery of electrons is J.J. Thomson.
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You titrate 25.0 mL of HCl solution of an unknown concentration with a 0.190 M NaOH solution. Complete neutralization of the HCl solution requires the addition of 24.6 mL of titrant.
A titration is defined as 'the process of determining the quantity of a substance A by adding measured increments of substance B, the titrant, with which it reacts until exact chemical equivalence is achieved (the equivalence point)'.
The Molarity of the HCl Solution requires the addition of 24.6 mL of titrant is 0.0836 M (to 3 significant figures)
What is Titrant?A reagent solution of precisely known concentration that is added in titration
Given reaction HCl + NaOH ===> NaCl + [tex]H_2O[/tex] neutralization reaction
Note that the mole ratio is 1:1 meaning that 1 mole HCl reacts with 1 mole NaOH to produce 1 mole NaCl and 1 mole [tex]H_2O[/tex]
Find moles of NaOH used:
18.45 ml x 1 L/1000 ml x 0.085 mol/L = 0.002091 moles NaOH used
This meant that there must be 0.002091 moles of HCl present in the 25.0 mls.
We want to find the molarity (M) which is moles HCl/liter of solution. We know the moles, and we also know the liters of solution (25.0 mls x 1 L / 1000 mls = 0.025 liters)
M = 0.002091 moles HCl / 0.025 liters = 0.08364 M = 0.0836 M (to 3 significant figures)
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FLAG A nurse is preparing to administer morphine 0.05 mg/kg intermittent IV bolus to a newborn who weighs 3 kg. Available is morphine 0.5 mg/mL injection. How many mL should the nurse administer? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)
The quantity of morphine, the nurse should administer is 0.3 ml.
What is morphine?Morphine is a drug which comes under the pain relieving drugs.
The quantity of morphine is 0.05 mg/kg
The weight of the baby is 3 kg.
Available morphine is 0.5 mg/mL.
0.05 x 3 = 0.15 mg
then, 0.15 mg / 0.5 = 0.3
Thus, the quantity of morphine, the nurse should administer is 0.3 ml.
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HCl + Fe + ____ + H²
Simple Way.
Hydrochloric acid + iron --> ______ + hydrogen gas.
• Answer this question, only if you know.
• Misuse of points will cost a report.
Answer:
This is a correct answer. 2HCL + Fe = FeCl2 + H2
The electron configuration of an element is 1s^2 2s^2 2p^6. Describe what most likely happens when an atom of this element comes near an atom having seven valance electrons. (5 points)
Answer:
In some cases, they could bond to form covalent compounds. However, in most instances they will not interact.
Explanation:
Remember that elements desire to have a full octet (8 valence electrons). The configuration given represents an element with 8 valence electrons. I know this because the outermost shell (denoted by the 2 coefficient) has 8 electrons (2s²2p⁶ = 2 + 6 = 8). Therefore, this element is stable.
The other atom has 7 valence electrons. Since it is 1 electron away from having a full octet, it really wants 1 more electron. The original element is unlikely to give up an electron because that would prevent it from having a full octet. As such, when the atoms are close to one another, they will most likely not interact. The element with the full octet is most likely a noble gas, and these elements rarely form bonds. Noble gases can form bonds with halogens (elements with 7 valence electrons) but only if there are excess halogens and particular noble gases in the system.
The electron configuration of an element is 1s2 2s2 2p6 is Neon with atomic number 10. They either will form covalent bond with other element of does not from bond with any other element.
What is chemical bond?Chemical bond is defined as any of the interactions that allow for the grouping of atoms into molecules, ions, crystals, and other stable species that make up ordinary substances.
It can also be defined as a connection between atoms in molecules or compounds, as well as between ions and molecules in crystals.
There are basically four types of chemical bond.
Covalent bondIonic bondMetallic bondMolecular bondThus, the electron configuration of an element is 1s2 2s2 2p6 is Neon with atomic number 10. They either will form covalent bond with other element of does not from bond with any other element.
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determine the number of gram of gas produced when 4.66 mole of water produced from the complete combustion of butane
.we can read the chemical preparation of the reaction as: "4 g of hydrogen react with 32 g of oxygen to give 36 g of water". :)
3) The following reaction produces chlorine molecules:
Energy + HCl (g) + CINO3 (8) Cl₂ (8) + HNO3 (8)
a) Describe 4 ways you could increase the concentration of chlorine molecules.
b) How would cooling shift the equilibrium of this reaction?
The 4 ways to increase the concentration of chlorine molecules is listed below and the reaction will go into reverse if cooled.
What is Le Châtelier’s principle ?
Le Châtelier's principle states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to reestablish an equilibrium.
Energy + HCl (g) + ClNO₃ ⇄ Cl₂ + HNO₃
a. So in this reaction when at equilibrium , To increase the concentration of Chlorine molecules
1. An increase in Temperature will favour the formation of Chlorine molecules.
2. Decrease in concentration of Chlorine , or partial removal of Chlorine will result the equation to go in forward direction.
3.An Increase in the concentration of HCl will favour formation of Chlorine molecules.
4.An Increase in the concentration of CINO₃ will also favour formation of Chlorine molecules.
b. The cooling would shift the reaction into backward direction as it is an endothermic reaction in forward state.
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The enzyme provided is a stock solution which should be diluted 50-fold with 0.001M HCl immediately before use.
Enzyme :1mg/ml chymotrypsin A in 0.001M HCl
How do I work out this calculation, if I want the 5ml of the diluted enzyme?
In order to prepare a 50-fold diluted enzyme, 0.1 mL of the stock solution of the enzyme is taken and made up to 5.0 mL with 0.001M HCl.
What is dilution?Dilution is a process whereby a solution of lower concentration is prepared from one of a higher concentration.
Dilution is done by using the dilution formula below:
C1V1 = C2V2C1; Initial concentration of enzyme = 1 mg/mL
C2; Final concentration of enzyme = 1/50 mg/ml = 0.02 mg/ml
V1; Initial volume of enzyme = y
V2; Final volume = 5.0 ml
V1 = C2V2/C1
V1 = 0.02 * 5/1 = 0.1 mL
Therefore, in order to prepare a 50-fold diluted enzyme, 0.1 mL of the stock solution of the enzyme is taken and made up to 5.0 mL with 0.001M HCl.
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Which of the following is the correct set-up for the problem: How many grams of water will be produced from 3.2 moles of oxygen and an excess of C2H4?
Option C is the correct set of the problem for mass of water produced by 3.2 moles of oxygen and an excess ethene.
Reaction between oxygen and etheneEthene (C2H4) burns in the presence of oxygen (O2) to form carbon dioxide (CO2) and water (H2O) along with the evolution of heat and light.
C₂H₄ + 3O₂ ----- > 2CO₂ + 2H₂O
from the equation above;
3 moles of O₂ ---------> 2(18 g) of water
3.5 moles of O₂ ----------> x
[tex]x = 3.2 \times [\frac{2 \ moles \ H_2O}{3 \ moles \ O_2} ] \times[ \frac{18.02 \ g \ H_2O}{1 \ mole \ H_2O} ][/tex]
Thus, option C is the correct set of the problem for mass of water produced by 3.2 moles of oxygen and an excess ethene.
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How many moles of aluminum do 6.4×1024 aluminum atoms represent?
Answer:
11 moles Al
Explanation:
To find the amount of moles, you need to use Avogadro's number to convert the atoms to moles. Since the value you were given has 2 significant figures, the final answer should also have 2 sig figs.
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
6.4 x 10²⁴ atoms Al 1 moles
---------------------------- x ------------------------------ = 10.6 moles Al
6.022 x 10²³ atoms
= 11 moles Al
How many protons,neutrons, and electrons does uranium 238 have
Explanation:
92 protons 92 electrons and 146 neutrons
Answer:
92 protons, 92 electrons, 146 neutrons
Explanation:
U-238 has 92 protons, 92 electrons, 146 neutrons.
The 238 is mass number talking about protons + neutrons. Uranium will always have 92 protons so the rest of the things are neutrons (146). Electrons will always equal protons if the element is neutral (no charge) and since no charge was given the numbers will match
Which of the following shows the wavelengths of light that an atom gives off when an electron falls to a lower energy level?
O A. Absorption spectrum
O B. Quantum spectrum
O C. Electromagnetic spectrum
O D. Emission spectrum
The wavelengths of light that an atom gives off when an electron falls to a lower energy level corresponds to Emission spectrum , Option D is the correct answer.
What is Emission Spectrum ?
Light is absorbed or emitted when an electron jumps or falls into an energy level.
The energy of light absorbed or emitted is equal to the difference between the energy of the orbits.
Therefore , the wavelengths of light that an atom gives off when an electron falls to a lower energy level corresponds to Emission spectrum.
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Monosaccharides and disaccharides are what kind of molecules?
Answer:
They are small molecules
Explanation: Hope this helps
Answer: C) Carbohydrates
Explanation:
A) Lipids
B) Nucleic acids
C) Carbohydrates
D) Proteins
apex
How do the valence electrons of an atom affect chemical reactions?
Answer:
Electrons of an atom can affect chemical reactions, because electrons have a negative charge, which can introduce a form of energy.
Question 2
2C4H10 + 1302 -> 8CO2 + 10H₂O
If 2.46 g H₂O are produced by a reaction, how many moles of C4H10 were used?
Answer:
2 mole of C4H10 were used in this reaction.
What volume of 12M HCI is needed to prepare 250
of 0.20M HCI?
Answer: 4.2
Explanation:
[tex]M_{A}V_{A}=M_{B}V_{B}\\(12)V_{A}=(250)(0.20)\\V_{A}=\frac{(250)(0.20)}{12}=\boxed{4.2}[/tex]
For the reaction
2A(g)+2B(g)+C(g)⟶3G(g)+4F(g)
the initial rate data in the table was collected, where [A]0 , [B]0 , and [C]0 are the initial concentrations of A , B , and C , respectively.
Experiment [A]0 (mmol⋅L−1) [B]0 (mmol⋅L−1) [C]0 (mmol⋅L−1) Initial rate (mmol⋅L−1⋅s−1)
1 11.0. 200.0 220.0 8.80
2 22.0 200.0 165.0 17.6
3 22.0 400.0 55.0 70.4
4 11.0 200.0 110.0 8.80
Reactant A is first order reactant, Reactant B is second order reactant, and Reactant C is zero order reactant...
1. What is the overall order of the reaction ______ ???
2. Write the rate law for the reaction where is the rate constant. Rate = k___???
3. Calculate the rate constant, , and identify its units. K = ____?????
4. Determine the initial rate of the reaction when [A]0=4.87 mmol⋅L−1 , [B]0=0.184 mmol⋅L−1 , and [C]0=12.0 mmol⋅L−1 . Initial Rate = _______ mmol⋅L−1⋅s−1 ??????
The overall order of the reaction is 3 and the rate law for the reaction is rate = [A]^n [B]^m [C]^l
How to find the Order of Reaction?
1) The order of reactant A is first order reactant because a first-order reaction can be defined as a chemical reaction in which the reaction rate is linearly dependent on the concentration of only one reactant.
The order of reactant B is second order reactant because a second order reaction is a type of chemical reaction that depends on the concentrations of one-second order reactant or two first-order reactants.
Thus, the overall order of the reaction is 3.
2) The rate law in this reaction is;
rate = [A]^n [B]^m [C]^l
But in this question, since the reactant C is zero order, then it will be simplified to; rate = k[A][B]² .
3) When we plug in the initial concentrations of A and B, we will get the rate constant of the problem which is k = 20.
4) The initial rate when [A]0=4.87 mmol⋅L−1 , [B]0=0.184 mmol⋅L−1 , and [C]0=12.0 mmol⋅L−1 is;
Rate = 20 * 4.87 * 0.184²
Rate = 3.3
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How many moles of MgCl2 where needed to make a 650.0 mL solution a concentration of 0.962 M?
Answer:
0.625 moles MgCl₂
Explanation:
Since you were given a molarity value and volume, you should use the molarity equation to find moles. The equation looks like this:
Molarity (M) = moles / volume (L)
To find moles, you need to (1) convert mL to L (by dividing by 1,000) and then (2) plug the numbers into the formula and simplify to find moles. The final answer should have 3 sig figs as the lowest amount of sig figs in a given value is 3.
Step 1:
650.0 mL / 1,000 = 0.6500 L
Step 2:
Molarity = moles / volume
0.962 M = moles / 0.6500 L
(0.962 M) x (0.6500 L) = moles
0.625 = moles
Atoms are spherical in shape. Therefore, the Pt atoms in the cube cannot fill all the available space. If only 74.0 percent of the space inside the cube is taken up by Pt atoms, calculate the radius in picometers of a Pt atom. The mass of a single Pt atom is 3.240 × 10−22 g. [The volume of a sphere of radius r is (4/3) πr3. The volume of a cube is l3, where l is the length of a side. Avogadro's number is 6.022 × 1023.]
Answer:
Answer:
A)6.6×10^22atoms of Pt in the cube
B)1.4×10^-8m
Explanation:
(a) Calculate the number of Pt atoms in the cube.
an edge length of platinum (Pt) = 1.0 cm.
Then Volume= 1.0 cm×1.0 cm×1.0 cm=1cm^3
Then we have volume of the cube as 1cm^3
Given:
The density Pt = 21.45 g/cm3
the mass of a single Pt atom =3.240 x 10^-22 g
Then with 1atom of the platinum element, we can calculate the number of Pt atoms in the cube as
Density of pt/mass of a single Pt atom
=(21.45 /=3.240 x 10^-22)
=6.6×10^22atoms of Pt in the cube
B)Volume of cube V=4/3πr^3
V= 4/3 ×π×r^3
V= 4.19067r^3
r^3= V/4.19067
But volume is not total volume but just 74% of it, then With 74% of the space inside the cube is taken up by Pt atoms, then we need to find 74% of volume of the cube which is 1cm^3
74/100 ×1= 0.74cm^3
Then our new volume V is 0.74cm^3
r^3=0.74/4.19067×6.620 x 10^22
r^3=2.6674×10^-24
r= 3√2.6674×10^-24
r=1.4×10^-8m
1. Related to the number of particles in a gram of
substance and to possible motions of the
particles (2 words)
Answer:
Avogadro's number or Avogardro’s constant
Explanation:
I’m pretty sure this is correct if it’s not I’m sorry lol.