The molar enthalpy of combustion in kj/mol of magnesium is 620 kj/mol, Option D is the correct answer.
What is enthalpy of Combustion ?The energy released when a fuel is oxidized by an oxidizing agent is called enthalpy of Combustion.
It is given that
a 1.0 g sample of magnesium is burned to form MgO. in doing so, 25.5 kj of energy are released.
Molecular weight of Magnesium = 24.35g
24.35 g makes 1 mole of Mg
1g = 1/24.35
For 0.04 moles 25.5 kJ is released
for 1 mole 25.5 *1/.04
= 620 kj/mol
Therefore the molar enthalpy of combustion in kj/mol of magnesium is 620 kj/mol.
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Assume that your electrical power company gets its energy from a hydroelectric dam. Outline all of the energy changes that occurred from the falling water that turned the generators at the dam to the hot air that was produced from your hair dryer this morning.
Answer:
See explanation.
Explanation:
This isn't chemistry. Its physics. Kinetic energy (water) to electric energy (dam) as the hydroelectric dam works. Then, as the current travels from the plant to your crib, electric energy to heat energy (wire resistance). Then when you are using the dryer electric energy to heat energy (hot air) and sound energy (air particles vibrate due to the heat energy).
The volume of a gas is 6.10 l, measured at 1.50 atm. what is the pressure of the gas in
mmhg if the volume is changed to 9.74 l?
Answer:
713.96mmhg
Explanation:
p1v1=p2v2
6.10×1.50/9.74
=0.939atm
=0.939*760
=713.96mmhg
The rate law for the reaction 3a ⟶⟶ c is rate = 4. 36 x 10–2 l • mol–1 • h–1[ a ]2 how long will it take in hours for the concentration of a to decrease from 0. 74 m to 0. 21 m?
The hours taken for concentration to decrease from 0 to 74 min. to 0.21 m is 91.7 hours.
What is the rate law of a reaction?Rate law depicts the rate of a chemical reaction depend on the concentration of the reactant.
The given reaction is second order reaction
Thus, the hours taken for concentration to decrease from 0 to 74 min. to 0.21 m is 91.7 hours.
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Examine the map and then answer the question.
North Sea
B
Allante
Ocean
A
Mediterranean
Otto von Bismarck united small independent states in which region?whats the answer
In 1867, Otto von Bismarck created the Northern Confederation, a combination of the northernmost German states beneath Prussian rule.
Who Was Otto Von Bismarck?The "Iron Chancellor," Otto von Bismarck (1815–1898), oversaw the unification and modernization of Germany. He virtually ruled Prussia and then all of Germany between 1862 until 1890. To unify the 39 autonomous German states under Prussian control, great strategist Bismarck launched decisive wars with France, Austria, & Denmark.
In 1864, Bismarck began the series of wars that'd make Prussia the most powerful country in Europe. He invaded Denmark to seize control of the German-speaking province of Schleswig-Holstein, and two years later he persuaded Emperor Franz-Josef I to start the Austria- War (1866), which brought about an immediate defeat for the faltering Austrian empire.
Thus, on 1867, Otto von Bismarck created the Northern Confederation, a combination of the northernmost German states beneath Prussian rule.
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Limonene is a volatile liquid which smells of oranges.
A teacher placed a beaker of limonene at the front of a classroom.
At first, the students at the back of the classroom could not smell the limonene.
After two minutes, the smell of limonene had spread throughout the classroom.
The air in the classroom was still and calm.
Explain these observations using the kinetic particle model.
Answer:
(limonene) particles go from liquid to vapour
diffusion
random movement of particles / particles move anywhere / particles move in all directions
spreading out of particles / intermingling of particles / mixing of particles / particles collide / particles bounce off each
other / particles go all over
(bulk) movement of particles from higher to lower concentration / movement of particles down concentration gradient
what is the half life of a radioactive sample if 100.0 grams of it decays to 12.5 grams in 24.3 hours
The Half-Life of the radioactive sample is 8.1 hours.
What is half life of a radioactive element?The half-life of a radioactive substance is the time taken for half the amount of atoms in the given substance to decay.
12.5 grams remains out of 100 grams of the sample.
This is 1/8 of the original samples.
1/8 of the original sample reperesent three half-lives undergone.
Half-Life of the radioactive sample = 24.3/3 = 8.1 hours
Therefore, the Half-Life of the radioactive sample is 8.1 hours.
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How many moles of ch4 are contained in 96. 0 grams of ch4.
Answer:
6 mol
Explanation:
Discussion
The answer is very nearly six. I will use rounded whole numbers to get the molar mass. Every periodic table is different so you will have to redo my numbers using your periodic table.
The trick is to find 1 mole of CH4 and divide that into 96.
Givens
96.0 grams of CH4
Solution
Find 1 mol of CH4
1 * 1C = 1 * 12 = 12 grams of Carbon in 1 mol of CH4
4 * H = 4 * 1 = 4 grams of Hydrogen in 1 mol of CH4
Total = 16 grams of C and H in 1 mol of CH4
Find 96 grams in mols.
Formula
mol = given mass / molar mass
given mass = 96 grams
molar mass = 16 grams
Mol = 96 / 16
Answer: mol = 6
From the dissolution of a gas sample, two more gases were obtained, namely 150 cm3 of N2 and 450 cm3 of H2 .What is the formula for dissolved gas.
please help
Which statement is true about a nickel-cadmium dry cell?
The anode reaction is NiO2+H2O+2e−→Ni(OH)2+2OH−.
The cathode reaction is Cd+2OH−→Cd(OH)2+2e−.
The cathode reaction is NiO2+H2O+2e−→Ni(OH)2+2OH−.
The cathode reaction is Cd+NiO2+2H2O→Cd(OH)2+Ni(OH)2.
Answer:
I think I answered this already but I'll put it again:
The cathode reaction is NiO2+H2O+2e−→Ni(OH)2+2OH−.
A 10.00 g sample of wood from an archaeological site produced 3072 counts in a 10-hour measurement owing to the presence of carbon-14, while a 10.00 g sample of new wood produced 9216 counts in the same period of time. The half-life of carbon-14 is 5730 years. How old is the wood from the archaeological site
From the calculation, the age of the sample of carbon - 14 is 9156 years.
What is radioactivity?The term radioactivity refers to the fact that a substance could disintegrate spontaneously when left alone.
Now, given that;
0.693/t1/2 = 2.303/t log (No/N)
t1/2 = half life
t = age of the sample
No = amount of sample originally present
N = amount of sample present at time t
Hence;
0.693/5730 = 2.303/t log (9216/3072)
1.2 * 10^-4 = 2.303/t * 0.4771
1.2 * 10^-4 = 1.09876/t
t = 1.09876/1.2 * 10^-4
t = 9156 years
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ILL GIVE BRAINLY!!!!!!
How many different elements are involved in the reaction shown below?
CH4 + 2 O2 → CO2 + 2 H2O
Answer:
four
Explanation:
There is four
CH 4 methane
O2 oxygen
CO2 carbon dioxide
H20 water
What is an example of service in the cement industry
Answer:
What kind of industry is cement industry?
The cement industry is one of the main industries necessary for sustainable development. It can be considered the backbone for development. The main pollution source generated from cement industry is the solid waste called cement by-pass dust, which is collected from the bottom of the dust filter.
Explanation:
Draw the Lewis structure for ClO.
The Lewis Structure for ClO. is attached in the image.
What is Lewis Structure ?Lewis structure represents the structure of atoms or molecules with their valence electron.
It is a two-dimensional model that helps us to know, how many bond pairs and a lone pair a molecule contains.
Lewis structure of ClO⁻ is very simple to draw as it has only two atoms(chlorine and oxygen), we have to just represent the valence electron around them and complete their octet.
1. Count total valence electron in ClO-
Total number of the valence electrons in chlorine = 7
Total number of the valence electrons in oxygen = 6
Total number of valence electrons = 7 + 6 + 1 = 14 valence electrons
[∴one oxygen atom, one chlorine, and one negative charge that count as a one valence electron]
2. Find the least electronegative atom and placed it at center
Connect outer atoms to central atom with a single bond Cl-O bond
Now count the valence electron in the above structure.
Single bond means two-electron , only one single bond is used.
Hence, only 2 valence electrons are used in the above structure from 14 total valence electrons available for drawing the lewis structure of ClO-.
(14 – 2) = 12
We have left with 12 valence electrons more.
3. Place remaining valence electrons starting from outer atom first
So, put the valence electron around the chlorine and oxygen.
we put 6 electrons around chlorine and oxygen, as each of them already sharing 2 electrons with the help of a single bond between them.
The structure can be seen in the figure attached.
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What happens when light enters water?
A. It’s speed stays the same
B. It speeds up
C. It can’t get back out
D. It slows down
Answer:
It slow down
It slow down when it passes from the less dense air into the denser glass or water
What is a real-life example of equilibrium and what would happen if there was a shift in the system of that example?
Answer:
Refrigerator
Explanation:
Think about it. Equilibrium is between 2 "places", and if you didn't open the fridge, there would be a buildup of cold air.
Because of that buildup, it would keep getting colder until it isn't possible to get cold anymore. That is equilibrium.
However, if you were to open the door for a very, very long time, you would lower the temp. inside the fridge, therefore causing for the room you are in to be slightly colder, and the fridge to decrease in cold. The fridge will still be slightly cold, but it won't be lukewarm if you leave it for 2 hours. (Unless it's broken)
That is equilibrium :)
please solve ...................................................................
Answer:
Explanation:
Part (c)
Mix together two suitable solutions.
Use filtration to separate the precipitate as a residue from the solution.
Wash the precipitate with distilled water while it is in the filter funnel.
Leave the washed precipitate aside or in a warm oven to dry.
Part (d)
Pb(NO3)2 (aq) + Na2SO4 (aq) → 2 NaNO3 (aq) + PbSO4 (s)
The general form AB àA + B represents which type of reaction?
Answer:
hope this helps and if you have any questions please feel free to ask me any time
Describe the method you could use to investigate the volume of hydrogen produced during the electrolysis of sodium chloride.
Answer:
Gas tests include:
hydrogen - lighted splint goes out with a squeaky pop.
Explanation:
phase changes lab, please! I need help fast deadline is really close.
Phase change occur in substances when the they change from one state of matter to another due to the addition or removal of heat.
What are phase changes?Phase changes refers to the changes that occur in substances in which they change from one state of matter to another due to the addition or removal of heat.
The phase changes that occur in substances are as follows:
change from solid to liquid known as meltingchange from liquid to gas known as vaporization change from solid to gas known as sublimation change from gas to solid known as deposition change from gas to liquid known as condensation change from liquid to solid known as freezingTherefore, phase change occur in substances when the they change from one state of matter to another due to the addition or removal of heat.
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For compounds of similar size and/or molar mass, which attractive force would result in the highest melting point
The compounds with high Intermolecular forces , will result in the highest melting point.
What is Melting Point ?The temperature at which the solid and liquid form of a solvent are in equilibrium and applying any more heat will lead to melting of the solid into liquid is called Melting Point.
The Intermolecular force that would result in highest melting point is the Ion-Ion interaction , the more the bonding the higher will be the melting point.
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1. If the pressure of a fixed volume of gas decreased in a sealed container, what variable would you think changed? did this variable increase or decrease?.
Answer:
Temp decreased
Explanation:
If the container is sealed and the pressure DEcreases, then the temperature DEcreased
PV = n RT n R V are constant if P goes down then so does T
How to balance the equation Mg2+HO2=Cu3O+H2
Which statement best describes an advantage of describing a system with a mathematical model?
A.
It enables people to calculate how a change in one variable will affect other variables.
B.
It helps people visualize the way that systems are interconnected.
C.
It simplifies the system by describing only one variable at a time.
D.
It allows people to manipulate something that looks like the actual system.
An advantage of describing a system with a mathematical model is that it enables people to calculate how a change in one variable will affect other variables.
Describes an advantage of a system with a mathematical model?A mathematical model usually describes a system by a set of variables and equations that formed relationships between the variables. Variables examples such as real or integer numbers.
So we can conclude that An advantage of describing a system with a mathematical model is that it enables people to calculate how a change in one variable will affect other variables.
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how does air move around the earth
What will be the efficiency of a machine which has an energy loss of 10%
The efficiency of the machine which has an energy loss of 10% is 90%
What is efficiency?This can be defined as the capacity to achieve a given task with little or no waste. Mathematically, it can be expressed as
Efficiency = (output / input) × 100
How to determine the efficiencyWe shall assume the following:
Input = 100 JOutput = 100 – 10 = 90 JEfficiency =?Efficiency = (output / input) × 100
Efficiency = (90 / 100) × 100
Efficiency = 90%
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Suppose that 5-ml containers of helium (He), neon (Ne), and argon (Ar) are at pressures of 1 atm,
2 atm, and 3 atm, respectively. The He and Ne are then added to the container of Ar.
a. What is the partial pressure of He in the container after the three gases are mixed?
b. What is the total pressure in the container after the three gases are mixed?
The total pressure in the container after the three gases are mixed is 6 atm and the partial pressure of He is 1 atm.
What is Dalton's Law of Partial Pressure ?According to Dalton's Law of Partial Pressure , the pressure exerted by a mixture of gas is equal to the sum of the partial pressure of the gases in the mixture.
P(total) = p₁ +p₂+p₃+.....
As the volume of the containers are same and the
n = 1*5/RT for Helium
n = 2*5 /RT for Neon
n= 3*5/RT for Argon
Mole fraction = moles of the element/Total moles
Moles fraction of Helium is
[tex]\rm \dfrac{1*5}{1*5+2*5+3*5}[/tex]
= 1/6
Total Pressure in the container = 1 + 2 +3 = 6 atm
The partial pressure of Helium will be
=Mole fraction * Total pressure
=(1/6)*6 atm
= 1 atm , as the volume is same the temperature is same , the pressure will also be same.
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What can scientists learn from radiometric dating?
A- how long ago a plant or animal lived
B- how much time it took a fossil to form
C- where a plant or animal lived
D- whether a fossil has modern relatives
Answer:
A- how long ago a plant or animal lived
Does anyone know what 5.7365 x 10^-5 + 3.4891 x 10^-8 is? in scientific notation preferably?
Answer:
5.7400 × 10⁻⁵
Explanation:
Among K, Ca and Ba, which element possess low ionization energy?
Among the elements Barium has the lowest Ionization Energy.
What is Ionization Process ?The process by which any neutral atom gets converted into electrically charged by gaining or losing electron is called Ionization Process.
K is an alkali metal it has to lose one electron to attain stable electronic configuration of an inert gas
For removing second electron , a stable configuration has to be broken and so will require high amount of energy.
Ca and Ba are alkaline earth metals.
They both have to lose 2 electrons to attain stable electronic configuration of noble gas.
They have low Iow Ionization Energy as compared to K.
Ca has higher Ionization Energy as compared to Ba because when we move down the periodic table , The ionization energy decreases.
Hence , Among the elements Barium has the lowest Ionization Energy.
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how do you treat a sulfuric acid burn with sodium hydroxide