A chemical reaction that takes place at constant pressure, the amount of heat absorbed or released by the system will be equal to the enthalpy change. The tool used to determine the change in heat is called a calorimeter, so the calculation is done by calorimetry.
EnthalpyEnthalpy is a state function. Therefore, the value of the enthalpy change depends only on the initial and final states, and does not depend on how the process of change occurs or the course of the reaction. Enthalpy is a physical quantity whose value is influenced by the amount and form of matter, and is influenced by the environment (temperature and pressure). Measurement of enthalpy at different temperatures and pressures will produce different enthalpy values. Therefore, it is agreed that a standard state is at a temperature of 298 K and a pressure of 1 atm.
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In an NF3 molecule, how many electrons does the nitrogen have?
A. 3
B. 5
C. 8
D. None of the above
Answer:
B
Explanation:
because I've just guessed and you've seen this but when you get this wrong and you see you'll wish you put that down
Consider the general reversible reaction. lower a upper a plus lower b upper b double-headed arrow lower c upper c plus lower d upper d. what is the equilibrium constant expression for the given system?
When a chemical reaction is reversible, the reactants from the initial reaction are created from the products as soon as they are formed.
There is no net change in the amounts of the substances involved because, at equilibrium, the two opposing reactions proceed at equal rates.
What traits distinguish reversible reactions?When both the conversion of reactants into products and the conversion of products back into reactants take place at the same time, the reaction is said to be reversible. A and B may combine to generate C and D, or in the opposite reaction, C and D may combine to create A and B. In thermodynamics, this is different from a reversible process.
All physical changes that result in a state change can be undone.
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What are the electron and molecular geometries, respectively, for hydrogen sulfide, h2s?.
Electron and molecular geometries, respectively, for hydrogen sulfide H₂S is electron geometry is linear and molecular geometry is bent
Molecular geometry is the three dimensional arrangement of atom that constitute a molecule and there are two lone pair present on the sulfur central atom in the H₂S molecule hence it will contract the bond pair and this make its shape appear like a bent structure and therefore the molecular geometry or shape of H₂S is bent while its electron geometry is tetrahedral because of four electron group around the sulfur
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A 0.425g sample of propane was mixed with excess oxygen in a calorimeter containing 98.72 g of water. The system was ignited and the temperature rose from 18.29ºC to 26.85ºC. The chemical equation for this reaction is :
C3H8 + 02 --> 3CO2 + 4H2O
Calculate the molar enthalpy of propane in J/mol
A 0.425g sample of propane was mixed with excess oxygen in a calorimeter containing 98.72 g of water. The system was ignited and the temperature rose from 18.29ºC to 26.85ºC. the molar enthalpy of propane is 393851.1 J/mol
The mass of propane = 0.425 g
molar mass of propane = 44 g/mol
moles = mass / molar mass
= 0.425 / 44
= 0.009 mol
ΔH = mc ΔT
ΔH = n ΔHsol
ΔHsol = mc ΔT / n
= 98.72 × 4.18 ( 26.85 - 18.29 ) / 0.009
molar enthalpy of solution = 393851.1 J/mol
Thus, A 0.425g sample of propane was mixed with excess oxygen in a calorimeter containing 98.72 g of water. The system was ignited and the temperature rose from 18.29ºC to 26.85ºC. the molar enthalpy of propane is 393851.1 J/mol
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Which food group has the largest carbon footprint and requires the most water to produce?.
Answer:
Explanation:
#1 (highest): Bovine meat (beef herd)
Beef has the highest carbon footprint of any food. This is because of what is required to raise and farm cattle. Animals used for beef production require a tremendous amount of feed, which must be grown on its own. They also produce an extremely high amount of methane
a 1 liter solution contains 0.567 m hydrofluoric acid and 0.425 m potassium fluoride. addition of 0.468 moles of hydrochloric acid will:
Several units of pH should be reduced.
go beyond the buffer's limit.
What purposes serve hydrochloric acids?In the food, textile, metal, and rubber sectors, hydrochloric acid (HCl) is frequently used to neutralise alkaline chemicals and as a bleaching agent. If discharged into the soil, it is neutralised, and water exposure causes it to hydrolyze quickly.
Raise the pH a little bit.
Reduce the pH a little.
Increase the pH by a few units.
Decrease the pH by a few units.
Do not alter the pH
Exceed the buffer's maximum size
Hydrochloric acid is created when potassium fluoride and hydrofluoric acid interact. The total of the HFO generated and the KFO consumed equals the amount of HCl supplied. All of the KFO is consumed, exceeding the buffer's capacity and reducing pH by several units, because moles of HCl > moles of KFO.
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A plate of cookies and mug of milk are pushed across a smooth table with the same force. The mass of the plate of cookies is 222 times the mass of the mug of milk. Assume that friction is negligible.
Due to the disparity in mass between the two objects, the acceleration of the two objects varies.
How to describe friction.Friction is the resistance to a thing moving or rolling over another solid object. Although they can be helpful, frictional forces, such as the traction required to walk without slipping, nevertheless pose a significant amount of resistance to motion.
Acceleration is influenced by mass. The acceleration decreases with increasing mass. A = f/m, or acceleration equals force times mass, is the formula for measuring speed. Due to the increased mass of the cookie plate compared to the milk glass, the acceleration is faster for the milk glass and slower for the cookie plate.
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Hello! I really need help on this chemistry worksheet. I don’t understand it.
Your shopping cart has a mass of 75 kilograms. In order to accelerate the cart at a rate of 0.5/s2, what force would you need to apply to the cart?
In order to accelerate the cart at a rate of 0.5/s2, the force needed is 37.5 N.
Acceleration is the rate of change of the velocity of an item with appreciation to time. Accelerations are vector portions. The orientation of an item's acceleration is given by the orientation of the net pressure appearing on that object.
Calculation:-
Mass = 75 kg
acceleration = 0.5 m/s²
F = ma
= 75 × 0.5
= 37.5 N
Acceleration is the charge at which velocity modifications with time, in terms of each speed and route. A factor or an object moving in a straight line is accelerated if it quickens or slows down. movement on a circle is extended despite the fact that the rate is consistent because the course is continually changing.
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Help me guys! Please
Answer:
D
Explanation:
chemical composition doesn’t change with physical change like freezing water will still make it h2o
Hopes this helps please mark brainliest
Q4. Hari mixed zinc with copper sulphate solution in a test-tube.
A displacement reaction took place and the temperature increased.
(a)
The word equation for the reaction is shown
below.
zinc sulphate + copper
Why is this reaction called a displacement reaction?
zinc + copper sulphate
When a less reactive element is pushed out of a compound that also contains a more reactive ingredient, the result is a displacement reaction.
Explain about the displacement reaction?The process by which iron and copper sulphate react to produce iron sulphate as a byproduct. Because iron is more reactive than copper in this situation, copper is replaced. zinc and iron sulphate reacting to produce zinc sulphate as a byproduct.
A single-displacement reaction occurs when a more reactive ingredient in a compound replaces a less reactive member. Metal displacement, hydrogen displacement, and halogen displacement are the three different categories of displacement processes.
A displacement reaction is a chemical process in which a more reactive element removes a less reactive element from its compound. For instance, zinc (Zn) substitutes copper in the reaction with copper sulphate (CuSO4) since zinc is more reactive than copper. Zn+CuSO4→ZnSO4+Cu.
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what do you call a uniform mixture of oily substances and watery substances? group of answer choices emulsion stain solvent gesso
A homogeneous suspension is created by whisking or blending two immiscible liquids, such as oil and water, to create an emulsion.
Depending on how the emulsion is made, the agitation creates either tiny oil droplets or water/vinegar droplets. If the chemical make-up of a combination remains constant throughout, it is said to be homogeneous. The salt water in the sample described above is homogeneous because the dissolved salt is dispersed uniformly throughout the entire salt water sample. A mixture of oil and water is known as an emulsion. A mixture of two separate liquids is referred to as an emulsion.
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identify nacl. group of answer choices weak acid strong electrolyte weak electrolyte nonelectrolyte strong acid
NaCl is a Strong electrolyte.
NaCl being a salt is strong electrolyte. It is a neutral salt. An electrolyte is substance which can conduct electricity in the solution. So a strong electrolyte is a good conductor of electricity. Strong electrolyte also have their ionisation value very high that means they have high degree of dissociation in solution. As NaCl splits completely into ions and have high degree of dissociation so it is a strong electrolyte. As NaCl can splits completely into Na⁺ and Cl⁻.
NaCl(aq) ⇄ Na⁺(aq) + Cl⁻(aq)
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predict how the reaction rate would change if the concentration of the sodium meta-bisulfite solution were changed instead of the potassium iodate
The reaction rate would increase.
In an acidic media, the reaction between potassium iodate and sodium meta-bisulfite produces iodine. Firstly, hydrogen sulfite and iodate ions are formed. Iodide ions are produced as a result of the reaction between iodate ions and hydrogen sulfite ions. Iodine is formed when the excess of iodate ions reacts with iodide ions in the existence of hydrogen ions. Iodine instantly combines with any remaining hydrogen sulfite ions to make iodide ions before it can mix with starch to form a dark blue-colored complex. The iodine is then free to combine with the starch to create the colorful complex after all of the hydrogen sulfite ions have completed their reactions. The color reveals the consumption of the sulfite ions. In order to observe this reaction, a known but constrained amount of sodium meta-bisulfite solution and starch solution can be added. The amount of time it takes for the blue color to develop is used to measure the rate of reaction. Overuse of bisulfite will stop the development of the dark blue complex.
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What volume of a 2. 000 m hcl solution is needed to generate 100. 0 ml of a 0. 1000 m solution of hcl?.
5ml of HCl is needed to convert a 2M molarity solution into a 0.1M solution of HCl that is 100ml in volume.
The HCl solution has a fixed molarity of 2M, and 100ml of a 0.1M molecular-weight solution is required for preparation. It is now necessary to determine the volume that will be required to make the 100ml 0.1M solutions.
M₁V₁ = M₂V₂
It is the dilution formula that should be used to achieve this.
We obtain,
2 x V₁ = 0.1 x 100 by entering the supplied values into the dilution formula.
2V1 = 10 V1
V₁ = 10/2
V₁ = 5ml
As a result, 5ml of HCl is needed to make 100ml of a 0.1M solution.
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how much lead paint contains 14.5% pbcr2o7 and 73% of the paint evaporates as it dries what mass of lead wil be in a paint chip that weighs 0.15g
0.15 grams of paint chip contains 0.0394 grams of lead.
Since we working with percentages, let's assume that we start out with 100 grams of paint.
Then, we have 14.5 grams of PbCr2O7, lead (II) dichromate, and 73 grams of the paint evaporates,
leaving us with 27 grams of dried paint, from which we extract our 0.15-gram chip.
The molecular mass of PbCr2O7 is 423.2 grams, and the atomic mass of lead is 207.2 grams, so
18.5 grams of PbCr2O7 contains 207.2 * 14.5 / 423.2 = 7.099 grams of lead.
If a 26.4-gram "chip" of paint contains 7.099 grams of lead, then a 0.15-gram chip should contain
0.15*7.099 / 27 = 0.0394 grams of lead.
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How iron turns into a brownish-red powder. Name the reactants and product that are involved.
a gas made up of atoms escapes through a pinhole times as fast as gas. write the chemical formula of the gas. tony st john
The chemical formula of the gas is Xe
Molar mass of H2 (M₂) = 2 g/mol
Rate of diffusion of H2 (r₂) = ?
Rate of diffusion of X (r₁) = 0.124r₂
molar mass of X (M₁) = ?
To calculate the molar mass of X we use graham's law of diffusion
[tex]\frac{r1}{r2} = \sqrt{\frac{M2}{M1} }[/tex]
[tex]\frac{0.124r2}{r2} = \sqrt{\frac{2}{M1} }[/tex]
[tex]{0.124} = \sqrt{\frac{2}{M1} }[/tex]
0.015 = 2 / M₁
M₁ = 2 / 0.015
M₁ = 133.3
133 is near 131.293 g/mol, which is the molar mass of xenon (Xe)
Therefore the chemical formula of the gas HX is Xe.
Complete question:
A gas made up of atoms escapes through a pinhole 0.124 times as fast as H2 gas. write the chemical formula of the gas.
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What is the grand formula mass of Cu(CN)2 please explain if you know.
The grand formula of mass is 115 grams.
Mass in grams is the atomic mass of one mole of an elemental or molecular or ionic compound. That is, the amount of a compound that has the same gram mass as the formula mass in unit atomic mass is called the gram formula mass. The formula mass of a molecule is the sum of the atomic weights of the atoms in the compound's molecular formula.
Calculation:-
molecular Mass Cu(CN)2= 63 + 2(12 + 14)
115 grams
The formula weight is the sum of the atomic weights of the atoms in the molecular formula of the compound formula. Multiply the atomic mass of each element by the total number of atoms/ions of that element in the formula. Add all the masses to get the form of the connection. The molar mass of a compound defines the mass of one mole of that particular substance and the number of grams per mole of the compound.
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Calculate the energy for the transition of an electron from the level to the level of a hydrogen atom.
1.63×10^-18J is the energy for the transition of an electron from the level n=1 to the level n= 2 of a hydrogen atom.
According to the Bohr equation for hydrogen atom,
Energy, ∆E= -RH[(1/nf2 ) - (1/ni2)]
Where RH is the Rydberg constant and its value is 109737.3cm-1, 'nf' and 'ni' are integers that represent the energy levels.
1). ni= 1 and nf= 2, substituting these values in Bohr equation,
∆E = -109737.3cm-1[(1/22). -(1/12)
= -109737.3cm-1[(1/4) -1]
= -109737.3cm-1[0.25-1]
= -109737.3cm-1(-0.75)
= 82302.975cm-1
=82302.975×1.986×10-23J
=1.63×10-18J
(where 1 cm-1= 1.986×10-23J)
Here the electron jumps from n=1 to n=2, so it must absorb a photon of light. Therefore this is an absorption process.
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How would the rate of disappearance of ethyl bromide change if the solution were diluted by adding an equal volume of pure ethyl alcohol to the solution?.
The question above isn't complete, as there's no reaction being written. That being said, assuming that the reaction is C2H5Br (alc) + OH ‾(alc) → C2H5OH (l) + Br‾(alc), the rate of disappearance of ethyl bromide would get reduced by 4 times or 1/4 of the original rate.
In the following reaction:
C2H5Br (alc) + OH‾ (alc) → C2H5OH (l) + Br‾ (alc)
The ethyl alcohol will dilute the concentration of each reactant to half of the original concentration. There are two reactants in the reaction, so the reaction rate after the addition of ethyl alcohol would be:
1/2 x 1/2 = 1/4 of the original rate.
In another word, the rate of disappearance of ethyl bromide will get reduced by four times after ethyl alcohol gets added to the solution.
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Liquefied petroleum (LP) gas burns according to the following exothermic reaction:
C3H8(g)+5O2(g)→3CO2(g)+4H2O(g)ΔH∘rxn=−2044kJ
What mass of LP gas is necessary to heat 1.3 L of water from room temperature (25.0 ∘C ) to boiling (100.0 ∘C )? Assume that, during heating, 15% of the heat emitted by the LP gas combustion goes to heat the water. The rest is lost as heat to the surroundings.
Express your answer using two significant figures.
Answer:
вау, это кажется сложным, но я все равно не знаю
At which temperature would the molecules in a one gram sample of water have the lowest average kinetic energy?
1. 5 Celcius
2. -100 Celcius
3. 5 Kelvin
4. 100 Kelvin
The temperature at which the molecules in a one-gram sample of water would have the lowest average kinetic energy is 5 Kelvin; option 3
What temperature would the molecules of a substance have the lowest average kinetic energy?The average kinetic energy of the molecules of a substance increases with an increase in temperature.
Thus, the average kinetic energy of the molecules of a substance will be highest at the highest temperature and lowest at the lowest temperature.
Considering the given temperatures of the water molecules, the highest temperature is 5 celsius and the lowest temperature is 5 Kelvin
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Electrons farther away from the nucleus in an atom have _______ compared to those closer to the nucleus.
Answer: More Energy
Explanation:
Electrons at higher energy levels, which are farther from the nucleus, have more energy. They also have more orbitals and greater possible numbers of electrons.
Can someone please help me with question 4&5
Answer:yes it 4
Explanation:
because u can divide
Please I need it ASAP
How many position of isomers /not chain isomers are possible for decene? Write their structures and name them.
Decene has a chemical formula of and has 75 isomers. In this example, all alkanes up to ten carbon atoms in length are meticulously listed starting with methane and proceeding in this manner.
Explain about the isomers?A nuclide isomeric with one or more others is one of two or more molecules, radicals, or ions that have the same number of atoms of the same elements but differ in their structural arrangement and characteristics.
The isomers known as structural isomers have the same chemical formulae but have their atoms totally rearranged in a different order. These are molecules with the same type of molecular formula but various connectivities based on the order in which they are assembled.
Carbon chains have the potential to branch, these isomers are created. For instance, the chemical butane, C4H10, has two isomers. One of them has a "straight chain" of carbon atoms, whereas the other has a branched chain.
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Consider each possible structure of carbon dioxide, c o 2. Determine whether the structure is correct and justify your decision.
This structure is correct due to the total number of bonds and electrons
We employ the octet rule, which states that all atoms in a compound are expected to follow, to check the accuracy of any chemical structure. The octet rule is precisely satisfied for each atom in the depicted structure of carbon IV oxide. The valence shell of each atom in the molecule is surrounded by eight electrons. We may thus infer that this structure is accurate given the total number of bonds and electrons since CO2 has sixteen valence electrons.
It possesses a negative charge of 1.602176634 coulombs, the basic unit of electric charge, which is comparable to its negative charge. The rest mass of an electron is 9.1093837015 10^-31 kg, or just 1/1,836 the mass of a proton. An electron is therefore considered to have practically negligible mass in comparison to a proton or neutron, and its matter is not taken into consideration when calculating an atom's mass number.
The question is incomplete, the complete question is found in the image attached to this answer
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how the water molecule interacts with various types of solutes (ionic, polar, non-polar) to dissolve them.
The water molecule interacts with various types of solutes to dissolve them , the water dissolves the ionic and the polar molecules but do not dissolves the non - polar molecules.
The water is called as universal solvent. the polar molecule and the ionic molecule have the partial positive and the negative charges. the water molecule also have partial positive and the negative partial so they will attract and dissolve in water. Non - polar molecules do not have positive and negative charges therefore they will not attracted to water and do not dissolve in water.
Thus, The water molecule interacts with various types of solutes to dissolve them , the water dissolves the ionic and the polar molecules but do not dissolves the non - polar molecules.
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if the percent yield for the following reaction is 75.0%, and 45.0 g of no2 are consumed in the reaction, how many grams of nitric acid, hno3(aq) are produced?
The gram of nitric acid is 30.82 grams of HNO3.
The molar mass of nitric acid is derived from the atomic mass of the element and its corresponding quantity. Percent Yield is a calculation that compares the amount of product you are actually producing with the amount of product you were calculated to be producing.
Calculation:-
Percentage yield = 76%
mass of NO2 consumed = 45 g
percentage yield = observed/actual ×100
obtained mass = 75× 45÷100
= 135/4
=30.82 gram
All real laboratory reactions always produce slightly less product than calculated. The yield rate measures how close you can get. Theoretical yields are calculated based on the stoichiometry of the chemical formula. Actual yield is determined experimentally. The yield rate is determined by calculating the ratio of actual yield/theoretical yield. Percent yield is a calculated number that indicates the percentage difference between the theoretical yield and the actual yield of the experiment.
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kay why ess (heart) (heart)<3 respectfully
Answer:
help me with my new question its science i got like 2 hrs left fr
Explanation:
