Answer: It takes 285.8 kJ of energy to form one mole of water
Explanation:
The enthalpy of formation of a substance is the change in enthalpy that occurs when a substance is formed from its elements in their standard states. The enthalpy of the formation of water is -285.8 kJ/mol, which means that it takes 285.8 kJ of energy to form one mole of water from its elements (hydrogen and oxygen) under standard conditions. This value is negative, which means that the formation of water releases energy. This is why water is often referred to as an "exothermic" substance because it releases energy when it is formed. The negative value of the enthalpy of formation for water can be explained by the fact that the bonds formed between hydrogen and oxygen atoms in water are stronger than the bonds between hydrogen and oxygen atoms in the individual elements. This means that it takes less energy to break the bonds in the elements than it releases when the bonds in water are formed, resulting in a net release of energy.
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Answer:
This means that 285.8 kJ/mol is evolved when one mole of water is formed.
What is the enthalpy of formation?
The term enthalpy of formation has to do with the energy that is released or absorbed when a molecule of water if formed from its constituents.
The fact that the enthalpy of formation of water is -285.8 kJ/mol implies that 285.8 kJ/mol is evolved when one mole of water is formed.
Explanation:
How many grams are in 4.2 × 10²² atoms of iron?
Answer:0.226 gram
Explanation:you can get the answer in two steps calculate 3.40 . 10^22 atoms =
Answer:
4.2 × 10²² ÷ 6.022× 10²³
4.2 × 10²² equals 0.069 moles (approx)
weight of 1 mole of iron = 56g
therefore, 0.069 moles = 56 × 0.069 = 3.9 g
Sorry for lazy work.. :P
CHEMISTRY FORM THREE Exercise 2.1 1) Not all metals share the typical metal properties.name a metal that is: a. hard and strong b. malleable at room temperature
a) The strongest metal on the planet is tungsten.
When it comes to tensile strength, tungsten tops all other metals. One of the strongest metals known to man, tungsten has an ultimate strength of 1510 Megapascals.
In addition to having the greatest melting point of any unalloyed metal, tungsten boasts greater strength. Tungsten is frequently employed in electrical and military applications due to its strength.
Tin is a malleable, silvery-white metal that is highly flammable at ambient temperature.
Metal malleability is a complex subject. There is no objective test available to measure this feature, as we previously stated. We most frequently test it for hardness.
The most malleable and ductile metals are gold and silver. Pure gold and silver are too soft to be used to create items that will keep their shape.
Metals may be molded into different shapes, such as thin sheets or foils, without breaking or shattering because they are malleable. They are also ductile, making it simple to draw them into wires.
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ammonia chemically reacts with oxygen gas to produce nitric oxide and water. what mass of oxygen gas is consumed by the reaction of 8.4 g of ammonia?
the mass of nitric oxide produced by the reaction of 8.4 g of oxygen gas is 4.32 g. ammonia chemically reacts with oxygen gas to produce nitric oxide and water.
What oxygen is used for?Common uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.
Why is oxygen important?Oxygen helps organisms grow, reproduce, and turn food into energy. Humans get the oxygen they need by breathing through their nose and mouth into their lungs. Oxygen gives our cells the ability to break down food in order to get the energy we need to survive.
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which of the following decreases with increasing atomic number in group 2
Answer: Ionization energy
Explanation:
Your welcome
Calculate the osmotic pressure of 5 % glucose solution and the osmotic pressure of 0.2 %, 0.9 % and 10 % sodium chloride solutions on the base of Van’t Hoff’s law (d = 1.1 g/ml for 10 % NaCl).
Based on Van't Hoff's law, the osmotic pressure of 5% glucose solution with 0.2%, 0.9%, and 10% sodium chloride solutions is 0821 liter atm K1mol1).
What is the osmotic pressure Van t Hoff law?Boyle, Van't Hoff The rule of solution: In a delute solution, the osmotic pressure () is directly proportional to the molar concentration (C) or inversely proportional to the volume (V) of the solution at constant temperature. Reason: C but C = Vn.
What does class 12 osmotic pressure formula mean?Pi=iMRT is the formula for osmotic pressure. The osmotic pressure increases with a solution's concentration (M) or temperature (T).
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Compared to a human, what is similar about how blue whales get molecules from food and air?
Answer: Blue whales, like humans, obtain molecules from food and air through a process of digestion and respiration. During digestion, molecules in food are broken down and absorbed into the bloodstream, while during respiration, oxygen molecules in the air are absorbed into the bloodstream. Both processes enable blue whales to obtain the necessary molecules for energy, growth, and development.
Rank the following fibers on the degree to which a dye will bind to the fabric and resist fading.
rank the following fibers on the degree to which a dye will bind
Answer:
polymer mear least receptive to dye
,
1. What is the modern view of electrons in the quantum mechanical model?
Answer: An electron con only exist in a limited number of quantized energy levels.
Explanation:
PLEASE HELP! 80 POINTS
Create a VESPR drawing for
NH3
CH20
N3
SO2CI2
BrF5
Answer:
hope it helps you
Bauxite is best used for making (1 point)
nails
wires
paints
drains
***missed it on test when answered wires****
To solve this we must be knowing each and every concept related to ore and bauxite. Therefore, Bauxite is best used for making wires. The correct option is option B.
What is bauxite?Aluminum's primary source of supply is bauxite. Due to its small weight and ease of molding into fine wire or sheets, aluminum is particularly useful.
All across the world, bauxite may be found. The greatest deposits of this ore are in Australia and Guinea, an African nation. Although bauxite was initially found in France, it may now be found all over the world, such as the Caribbean.
Therefore, Bauxite is best used for making wires. The correct option is option B.
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8. Jill conducted an experiment to investigate which plant food would make her
plants grow faster. She tried four different plant foods on plants of the same
type and age. Jill concluded that the plant that was fed Brand A grew the
fastest. Jill did not realize that the plant that was fed Brand A also received
more sunlight. (SC.7.N.1.5.3)
What error did Jill make in her experiment?
a) She used the wrong kind of plant.
b) She used too much plant food.
c) She did not control the variables.
Are all antigens foreign substances?
No, not all antigens are foreign substances.
An antigen is any substance that can trigger an immune response, including the production of antibodies. Some antigens are naturally present in the body and are called "self" antigens which are usually not harmful, but in some cases, the immune system can mistakenly recognize them as foreign and attack them which can lead to autoimmune diseases.
Antigens bind together with antibodies and promote the elimination of harmful pathogens present in the body. They alert other parts of the immune system to take over which helps to neutralize the threat from pathogens.
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The reaction below shows the combustion of propane (C3H8). Why is the mole ratio (3 moles CO2/1 mol C3H8) used to determine the amount of carbon dioxide (CO2) produced when propane (C3H8) combusts in excess oxygen? (1 point) C3H8 + O2 yields CO2 + H2O + heat Propane has a mass that is 3 times greater than that of CO2, so only 1 mole of C3H8 is needed to produce 3 moles of CO2. When the chemical equation for propane combustion is balanced, 1 mole of C3H8 is needed to produce 3 moles of CO2. During combustion, CO2 is approximately 3 times more reactive than C3H8, so less C3H8 will participate in the reaction. Carbon dioxide has a volume of about one-third that of C3H8, so 3 moles of CO2 are needed to react with each mole of C3H8.
One mole of the propane produces three moles of the carbon dioxide from mole ratio.
What is the mole ratio?When we talk about the mole ratio, we mean the ratio of the species that can be found in the reaction. We can be able to get the mole ratio from the balanced reaction equation and we apply it to solve problems from the stoichiometry of the reaction.
Given the fact that we have the reaction as it has been written in the question, it is clear that we would need about one mole of the propane to produce three moles of carbon dioxide.
We can see that there are three atoms of carbon in the propane and the implication of this is that we are going to produce three atoms of carbon dioxide in the product.
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The diagram at right shows a manometer connected to a flask. The mercury levels are measured in mm. the pressure in the room is 740mmHg. Determine the pressure of the gas in the flask.
on the flask it has 505mm and 465mm
pressure=585...
this is your answer
When air moves in small circular patterns, it moves within a
Answer:
Convection
Explanation:
A transverse wave is shown here. Several wave properties are labeled with letters. Which of these statements accurately reflects the energy associated with the wave? Select ALL that apply. Responses A Y is the frequency, and an increase in Y is associated with an increase in energy.Y is the frequency, and an increase in Y is associated with an increase in energy. B W is the amplitude, and a decrease in W is associated with an increase in energy.W is the amplitude, and a decrease in W is associated with an increase in energy. C W is the amplitude, and an increase in W is associated with an increase in energy.W is the amplitude, and an increase in W is associated with an increase in energy. D Z is the displacement, and a decrease in Z is associated with an increase in energy.Z is the displacement, and a decrease in Z is associated with an increase in energy. E X is wavelength, and a decrease in X is associated with an increase in energy.
Answer:
C) W is the amplitude, and an increase in W is associated with an increase in energy.
E) X is wavelength, and a decrease in X is associated with an increase in energy.
Explanation:
A transverse wave consists of an oscillating electric field that is perpendicular to the direction of the wave. Increasing either the amplitude or the wavelength of the wave increases its energy. For a transverse wave, the amplitude corresponds to W, while the wavelength is labeled X. So increasing W or decreasing X will create increase the energy of the wave.
Using the balanced equation
how many
3Ba+Al2(SO4)3-->2Al+3BaSO4,
grams of aluminum will be produced if 1.0 g of Ba react with 1.80 g of
Al2(SO4)3?
O.14
0.26
0.28
O.13
Grams of aluminum that will be produced if 1.0 g of Ba react with 1.80 g of Al2(SO4)3 will be 0.28g Al. Hence option c) is correct.
What is balanced equation?A balanced equation is a chemical equation where mass is conserved and there are equal numbers of atoms of each elements on both the sides of equation.
Given, 1.80 g of Al2(SO4)3 and 1.0 g of Ba
So, (1.8 g)/(341.96 g) = 0.00526 moles of Al2(SO4)3
And, 1 mole = 341.96g Al2(SO4)3
Now, (0.00526 moles of Al2(SO4)3)*(2 moles of Al)
= 0.01052 moles of Al
So, (0.01052 moles of Al)*(27 grams of Al)
= 0.28g Al
Hence, option c is correct.
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A chemist morning commute is 40.2 kilometers. Given an average speed pf 60.5 mph, how many minutes will it take him to arrive at work?
A chemist morning commute is 40.2 kilometers. Given an average speed pf 60.5 mph, 0.66 minutes will it take him to arrive at work.
What is average speed ?The overall distance the object covers in a given amount of time is its average speed. A scalar value represents the average speed. It has no direction and is indicated by the magnitude.
If you know how far something has travelled and how long it took to get there, you can calculate its average speed. Speed is calculated as follows: speed = distance * time.
Distance = speed × time
40.2 = 60.5 × time
time = 40.2 / 60.5
= 0.66 minutes
Thus, A chemist morning commute is 40.2 kilometers. Given an average speed pf 60.5 mph, 0.66 minutes will it take him to arrive at work.
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What is the number of chloride ions (Cl-) in 250 mL of a 0.2M magnesium chloride solution?
a. 0.1 mol c. 0.62 mol
b. 0.16 mol d. 1.6 mol
According to molar concentration and mole concept, there are 0.1 mole of chloride ions in 250 mL of a 0.2 M magnesium chloride solution.
What is molar concentration?Molar concentration is defined as a measure by which concentration of chemical substances present in a solution are determined. It is defined in particular reference to solute concentration in a solution . Most commonly used unit for molar concentration is moles/liter.
In terms of moles, it's formula is given as molar concentration= number of moles /volume of solution in liters.
By substituting values in given formula, number of moles=0.2×0.250=0.05 moles .Now this values is subtracted from molar mass of magnesium chloride that is 95.211-0.05=95.161 moles which is finally divided by 95.211=0.999 which is approximately 0.10 mole.
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Q. 2 A and B are powders, A is insoluble while B dissolves to give a pH 3 solution. Mixing A and B gives bubbles or effervescence and a clear solution. Which is the acid? If the other substance is a carbonate, name the gas given off. Even though A is insoluble a clear solution is given off, explain why.
Answer:
From the information provided, it seems likely that substance A is an acid, and substance B is a carbonate. The fact that mixing the two substances results in bubbles or effervescence, and that a clear solution is formed, suggests that a chemical reaction is taking place.
Acids and carbonates react together to form a salt, water, and carbon dioxide gas. The reaction is as follow:
Acid + Carbonate → Salt + Water + Carbon Dioxide
The carbon dioxide gas forms bubbles in the solution and causes effervescence, and the clear solution formed is due to the fact that both the acid and the carbonate have reacted together to form the salt and water. This reaction is acid-base neutralization reaction as the acid and base will neutralize each other.
As for the acid, since it is said that B gives pH 3 solution after dissolved, it can be inferred that it is not an acid, otherwise it would be acidic. Therefore A which is insoluble is the acid.
As for the gas given off, it's Carbon dioxide.
Explanation:
What is the empirical formula of a compound consisting of 48.64% C, 8.16% H, and 43.20% O by mass? Assume 100.0g total of unknown compound.
Answer:
empirical formula of the compound is CH2O
Explanation:
Assign oxidation numbers to each atom in each substance. Then check your work by summoning to zero for each compound or the charge on the ion for the polyatomic. (Please help I am awful at chemistry )
The oxidation number of the atoms in the given compounds are :
K₂O: K = + 1; O = -2;
PO₃⁻³: P = +3; O = -2
NH₃: N = -3; H = +1
Cu(NO₃)₂: Cu = +2; N = +5; O = -2
NO₃⁻¹: N = +5; O = -2
CO₂: C = +4; O = -2
KClO₃: K = +1; Cl = + 5; O = -2
O₂: O = 0
Ca(ClO₄)₂: Ca = +2; Cl = +7; O = -2
What is the oxidation number of elements?The number of electrons an atom or ion has either gained or lost in comparison to the neutral atom is known as the oxidation number or state of the atom or ion.
Group I, 2, and 3 electropositive metal atoms lose a certain number of electrons, and their positive oxidation numbers remain constant.
The oxidation number of the atoms in the given compounds are as follows:
K₂0
K = + 1
O = -2
Sum is (+1 * 2) + (-2) = 0
PO₃⁻³
P = + 3
O = -2
Sum is (+3) + (-2 * 3) = -3
NH₃
N = -3
H = +1
Sum is (-3) + (+1 * 3) = 0
Cu(NO₃)₂
Cu = +2
N = +5
O = -2
Sum is (+2) + (+5 * 2) + (-2 * 6) = 0
NO₃⁻¹
N = +5
O = -2
Sum is (+5) + (-2 * 3) = -1
CO₂
C = +4
O = -2
Sum is (+4) + (-2 * 2) = 0
KClO₃
K = +1
Cl = + 5
O = -2
Sum is (+1) + (5) + (-2 * 3) = 0
O₂
O = 0
Sum is (0 * 2) = 0
Ca(ClO₄)₂
Ca = +2
Cl = +7
O = -2
Sum is (+2) + (+7 * 2) + (-2 * 8) = 0
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What is the domain of the following function?
A) x < 15
B) x ≤ 4
C) x > 2
D) All Real Numbers
The domain of the function that has been shown are all real numbers. Option D
What is the domain of a function?Let us note that when we are talking about the domain of the function, we mean the areas that the function is able to have a value. We are also trying to define the areas where the actual value of the function can be determined.
It is normal that all the mathematical functions that we have must have a domain and a range. The domain of the function would depend on the kind of function that it is and that determines what its domain would be.
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Iron has a density of 7.31 g/cm3.what is the mass of 2.25 cm3 of sodium?
7.9 g/cm3 is the density of iron. There are three possibilities: 1.3 × 103 g 2.3 × 10-2 g 4.3 × 102 g 2.1 × 104 g 1.4 g.
What is the density of iron?Iron has a density of 7.874g/cm3.
At atmospheric pressure, different substances have their typical densities.
The mass per unit volume is the definition of density. Mathematically speaking, its intense attribute is defined as mass divided by volume:
ρ = m/V
The total mass (m) of a material divided by the total volume (V) . it occupies is how a substance is defined as having a density (). The kilogram per cubic meter (kg/m3) is the metric unit used by the SI. The pounds mass per cubic foot (lbm/ft3) measurement is used in Standard English.
Compressibility (also known as the coefficient of compressibility is a measure of the relative volume change of a fluid or solid as a response to a pressure (or mean stress) change.
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hydrates (1 question)
6) When 10.000 g of a hydrated compound are analyzed in the laboratory, the following analysis is obtained: 1.425 g of water, 5.462 g of lead, 1.266 g of carbon, 1.687 g of oxygen, and 0.160 of hydrogen. What are the name and formula of the compound?
The name and formula of the compound can be determined by analyzing the data given in the question. Based on the information provided, the compound contains lead, carbon, oxygen, and hydrogen. The molecular formula for the compound can be determined by adding up the number of atoms of each element present.
From the data given, the compound contains 1.266 g of carbon, which is equivalent to 1.266/12.01 = 0.105 mol of carbon atoms. It also contains 5.462 g of lead, which is equivalent to 5.462/207.2 = 0.026 mol of lead atoms. The compound also contains 1.687 g of oxygen, which is equivalent to 1.687/16.00 = 0.105 mol of oxygen atoms, and 0.160 g of hydrogen, which is equivalent to 0.160/1.01 = 0.158 mol of hydrogen atoms.
The molecular formula for the compound is therefore Pb(C2H2O2). However, it is also mentioned that the compound is hydrated, which means that it contains water. The 1.425 g of water present in the compound is equivalent to 1.425/18.02 = 0.079 mol of water molecules. The compound 1 likely Pb(C2H2O2)·xH2O, where x represents the number of water molecules present in the compound.
Please show all of your work, I need to understand all steps:
A student collected time (t) and concentration ([A]) data at
295 K for the reaction 2A→B. These time and concentration data are shown in the table to the right. The student then plotted graphs of [A] versus t (Figure 1) , ln[A] versus t (Figure 2) , and 1/[A] versus t (Figure 3) .
Figure 1:
t (s) (A)(M) ln(A) 1/ (A)
0.00 0.500 −0.693 2.00
20.0 0.389 −0.944 2.57
40.0 0.303 −1.19 3.30
60.0 0.236 −1.44 4.24
80.0 0.184 −1.69 5.43
i.) What is the rate of the reaction?
ii.) What is the value of the rate constant for this reaction?
iii.)
Next, the student ran the same reaction at a different temperature and measured a different reaction rate, with the following results:
T(K) k(s-1)
295 0.0125
325 0.0357
What is the activation energy of this reaction?
Express your answer to three significant figures and include the appropriate units.
Answer:
a because the x and y value is the same
C(s) + O2(g) → CO2(g) ΔHº = -94.6 kJ
H2(g) + \scriptsize \frac{1}{2}O2(g) → H2O(l) ΔHº = -286.0 kJ
2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O (l) ΔHº = -2598.8 kJ
calculate the value of ΔHº for the final reaction:
2C(s) + H2(g) → C2H2(g) ΔHº = kJ
The value of enthalpy(ΔHº) for the final reaction (2C(s) + H₂(g) → C₂H₂(g) ) is -1932.8KJ.
Enthalpy change: what is it?A system's enthalpy is its heat capacity. A reaction's enthalpy change is roughly equivalent to how much energy is lost or gained throughout the reaction. If the enthalpy of the system decreases over the reaction, the reaction is preferred.
C(s) + O₂(g) → CO₂(g) ΔHº = -94.6 kJ --- (1)
H₂(g) + O₂(g) → H₂O(l) ΔHº = -286.0 kJ ---(2)
2C₂H₂(g) + 5O₂(g) → 4CO₂(g) + 2H₂O (l) ΔHº = -2598.8 kJ ---(3)
The value of ΔHº for the final reaction,
2C(s) + H₂(g) → C₂H₂(g)
ΔH₄° = 2× ΔH₂º + ΔH₃º - ΔH₁º
ΔH₄° = 2× -286.0 + ( -2598.8) - (- 94.6)
ΔH₄° = 2× -286.0 -2598.8 + 94.6
ΔH₄° = 666 - 2598.8
ΔH₄° = -1932.8KJ.
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_____ molecules are always synthetic.
A synthetic ingredient is a substance that has been synthesized in a lab using different chemical procedures. Its goal is to mimic a natural chemical to duplicate its structure and, consequently, its fragrance.
What is synthetic ingredient?In most cases, it refers to a naturally occurring substance, like hyaluronic acid, which was formerly extracted from animals and has now been molecularly copied in a laboratory to provide the same results. Not everything that is manufactured or chemical is inherently harmful to you. Although not all synthetic cosmetic components are the same, some have been proven to be toxic, accumulate in the body over time, and have been associated with cancer as well as irritations of the skin and mucous membranes.
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The half-life of Po-218 is three minutes. How much of a 2.0 gram sample remains after 15 minutes? Suppose you wanted to buy some of this isotope, and it required half an hour for it reach you. How much should you order if you need to use 0.10 gram of this material?
(2)(½^(15/3)) = 0.0625 (5 half-lives) 102.4 grams order
What is the half-life of an isotope?A radionuclide's half-life is the amount of time it takes for half of its radioactive atoms to decay. A good rule of thumb is that you will have less radiation than 1% of the original amount after seven half-lives.Knowing an element's alpha, beta, or gamma decay can help someone properly protect their body from excessive radiation. Within one half-life, the amount of radioactive nuclei present at any particular time will be reduced to half.Each radioisotope has a set half-life that can be anywhere between a few milliseconds (for example, 215At at 0.1 milliseconds) and billions of years (e.g.,238U at 4.468 billion years). Both stable and radioactive isotopes can exist for an element.The period of time needed for something to go from 50% to 50%To learn more about half-life of an isotope refers to:
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the maximum allowed concentrations of chloride in municipal drinking water supply in 250 ppm cl. when the supply of water exceeds this limit it often has a distinctive salty taste. what is the concentration in molarity?
The allowed concentration of Cl in water is 250 ppm. Then the equivalent concentration in molarity is 0.007 molar.
What is molarity ?Molarity is a common term used to express the concentration of a solution. It is the ratio of the number of moles of solute to the volume of solution in liters. Molarity is a temperature dependent measurement.
Parts per million is another term of concentration have the formula as written below:
ppm = ws/W × 10⁶
Where, ws is the weight of solute and W be the weight of solution in grams.
1 molar = 35500 ppm
therefore, 250 ppm = 250 ppm × 1M /35500 ppm = 0.007 M.
Hence, the molarity of the salt solution will with the maximum allowed concentration will be 0.007 M.
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