The substances that have Delta Hf = 0 kJ/mol are O2(g), Br2(l), He(g), Fe(s).
What is delta Hf = 0?Delta Hf = 0 is the standard enthalpy of any element in its most stable form is equal to zero.
When enthalpy is negative, the delta Hf is minus zero, which means the system releases heat.
When the system gains heat, the delta Hf is positive.
Thus, the substances are O2(g), Br2(l), He(g), Fe(s).
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Answer:
1,4,5,6
Explanation:
How many moles of carbon dioxide (CO2) are equivalent to 4.55 X 10^24 molecules?
A. 4.55 moles
B. 7.56 moles
C. 15.1 moles
D. 22.7 moles
Answer:
b
Explanation:
use Avogadro's number to convert molecules to moles
1 mole is equal to 6.023 × 10 ²³ molecules. 7.56 moles of carbon dioxide (CO2) are equivalent to 4.55 X 10^24 molecules.
What do you mean by mole ?The term mole is defined as the amount of substance of a system which contains as many elementary entities.
One mole of any substance is equal to 6.023 × 10²³ units of that substance such as atoms, molecules, or ions. The number 6.023 × 10²³ is called as Avogadro's number or Avogadro's constant.
The mole concept can be used to convert between mass and number of particles.
1 mole of any substance = 6.023 × 10²³molecules
1 mole of carbon dioxide = 6.023 × 10²³molecules
Then 4.55 X 10^24 molecules of CO₂ = 4.55 X 10^24 × 1 mole / 6.023 × 10²³
= 7.56 moles
Thus, 7.56 moles of carbon dioxide (CO2) are equivalent to 4.55 X 10^24 molecules.
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Which statement is correct about the theory of combustion? (1 point)
A. The law of conservation of mass provided justification for the theory of combustion.
B. The theory of phlogiston provided justification for the theory of combustion.
C. The theory of phlogiston became the theory of combustion.
D.The law of conservation of mass became the theory of combustion.
The theory of phlogiston was the first to explain combustion process. J.J Becher was proposed this theory and states the existence of phlogisticated substances contain phlogiston and that they dephlogisticate when burned.
What is combustion ?Combustion is the reaction of gases with atmospheric oxygen producing carbon dioxide and water. Gases like hydrocarbons easily undergoes combustion reaction.
Combustion is an exothermic reaction. Thus, heat is evolved to the surrounding. The conservation of mass is not only for combustion but it is the theory of every reaction.
The phlogiston idea, a debunked scientific hypothesis, suggested that combustible bodies contained a fire-like substance called phlogiston, which was produced after combustion.
Johann Joachim Becher originally put out the concept in 1667, and Georg Ernst Stahl later formalized it. The Phlogiston theory sought to explain a variety of chemical reactions, including burning and rusting Hence, option C is correct.
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Where can you change the atom/molecules used in the simulation? Which atoms/molecules are
available for you to choose?
Answer:
When two or more atoms are chemically joined together, this is called a molecule. In some cases, such as hydrogen and oxygen, the molecule is made entirely of the same atom, such as hydrogen gas (a molecule) is made entirely of two hydrogen atoms. Here, converting molecules to atoms is as simple as dividing by two.
Atoms can join together - they form bonds together - to make MOLECULES. For example, two atoms of hydrogen hook together to form a molecule of hydrogen
If you had a mixture of butyric acid and hexane, how would you separate the two compounds?.
Answer:
First of all take separatory funnel.
Add the mixture of compounds into it.
Pour Water into it.
Add NaOH base. This will result in following reaction.
CH₃CH₂CH₂COOH + NaOH → CH₃CH₂CH₂COONa + H₂O
The resulting salt (CH₃CH₂CH₂COONa) is is soluble in water.
The water is the bottom layer (more density) and contains sodium butyrate.
Pour out the water from separatory funnel.
The organic layer (hexane) is left behind.
Now, take the aquous layer and neutralize it using HCl.
Once, neutralized remove the water.
5 points
15. Given the formula below: What is the change in the water's freezing
point when 75 grams of NaCl is added to 400 grams of H20? (Kf water -
1.86 C/m) *
Change in Temp = - ix K, x m
- 0.119 ° C
- 1.19 ° C
O A
B.
- 11.9°C
- 119°C
C
Molarity
[tex]\\ \tt\hookrightarrow \dfrac{1.3}{0.42}=3.09M[/tex]
Now
[tex]\\ \tt\hookrightarrow \Delta T=K_f\times m\times i[/tex]
m is MolarityI is vant Hoff factor[tex]\\ \tt\hookrightarrow \Delta T=1.86(3.09)(2)=11.5°C[/tex]
Hey yall any answers
Answer:
January = 45
May = 80
Explanation:
45 + 8 = 53
53 + 8 = 61
61 + 8 = 69 Round 70
70 + 8 = 78 Round 80
[RevyBreeze]
Answer: i might 45 and 110 because i think that it is adding or something
Explanation:
How do you increase the absorbance of a sample with a fixed concentration?.
Describe how the four most common chemicals weather materials. Provide examples
Answer:
Chemical weathering occurs when water dissolves minerals in a rock, producing new compounds. ... Hydrolysis occurs, for example, when water comes in contact with granite. Feldspar crystals inside the granite react chemically, forming clay minerals. The clay weakens the rock, making it more likely to break.
Carbonation-As rain goes through the air and into the ground, it grabs carbon dioxide, creating carbonic acid. This weak acid reacts with the calcium carbonate in stones when it seeps into the cracks.
Oxidation- Rust forms when the iron or steel in your car reacts with the oxygen in the air to form iron oxide. The resulting red substance can be quite brittle, so much so that you could literally poke a hole in it with your finger. Rocks with iron can go through the same process, too.
Hydration- Hydration is a type of chemical weathering where water reacts chemically with the rock, modifying its chemical structure.
Acidification-Acid rain is water with sulfuric and nitric acids from the burning of coal and fossil fuels, along with volcano eruptions. The acids create a reaction when they hit the stone, causing the surface to wear and the composition to soften. Acidification can also be caused by organisms like lichens, which are created from algae and fungi.
Which group is arranged correctly in order of increasing energy for electrons in an element?
(A) 2p,2s,1s
(B) 3p,4s,3d
(C) 3s,3d,3p
(D) 2s,4p,3d
(E) 3p,4s,4d
Answer:
E.)3p,4s,4d
Explanation:
In order as: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p… 1s will be filled first, with the maximum of 2 electrons. 2s will be filled next, with the maximum of 2 electrons. 2p will be filled next, with the maximum of 6 electrons.
B) 3p, 4s, 3d
hope this helped
name the reasons why chemistry is important in industry
Answer:
Chemistry is essential for meeting our basic needs of food, clothing, shelter, health, energy, and clean air, water, and soil. Chemical technologies enrich our quality of life in numerous ways by providing new solutions to problems in health, materials, and energy usage
Answer:
▪Why Is chemistry important in industry?
[Chemistry helps our industry produce more materials—such as paints, plastics, iron or steel, cement, kerosene, and also motor oil. Chemistry also helps farmers to enrich the soil with chemicals ... to grow fresh vegetables.] Chemistry is important, especially in household things like condoms, cleaning, and cooking.
▪10 Reasons Why Chemistry Is Important
➢Chemistry helps explain everything.
➢Being interested in chemistry opens up career options.
➢Chemistry helps people develop strong analytical skills.
➢Understanding chemistry keeps people safe.
➢Chemistry helps protect the environment.
➢Chemistry is used in law.
➢Chemistry is used in the food industry
➢Chemistry is important in agriculture
➢Chemistry is used in medicine
➢Chemistry is important for space travel
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Light of a certain energy shines on a metal and causes electrons to be emitted.
Answer:
I believe your answer is D. The use of light that has a lower frequency.
Hope this helped!
Is friction felt in all surfaces?
Explanation:
Friction is a force that opposes motion between any surfaces that are touching. Friction occurs because no surface is perfectly smooth. Rougher surfaces have more friction between them. Heavier objects also have more friction because they press together with greater force..
.
. please mark me brrenlist ✨ ⭐A 3.00mol sample of CO2(g) is in a rigid 6.00L container at 400.C∘ .
Which of the following is the pressure of the gas?
16.4atm
Answer A: 16.4 atmospheres
A
27.6atm
Answer B: 27.6 atmospheres
B
200.atm
Answer C: 200 decimal point, atmospheres
C
995atm
The pressure of the gas that has 3.00mol sample of CO2(g) is in a rigid 6.00L container at 400°C is 27.6atm.
HOW TO CALCULATE PRESSURE?The pressure of a gas can be calculated using the ideal gas law equation as follows:
PV = nRT
Where;
P = pressureV = volumen = number of molesR = gas law constantT = temperatureP = ?v = 6Ln 3 molR = 0.0821 molL/KatmT = 400 + 273 = 673KP × 6 = 3 × 0.0821 × 673
6P = 165.76
P = 165.76 ÷ 6
P = 27.6atm
Therefore, the pressure of the gas that has 3.00mol sample of CO2(g) is in a rigid 6.00L container at 400°C is 27.6atm.
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Define the following:
Organic Acid.
Dilute Acid.
Indicator
Neutralization.
Acid Rain
Answer:
Please see below
Explanation:
Organic acid - An organic acid is an organic compound with acidic properties. Organic acids should include amino acids, fatty acids, ketoacids, and a variety of other endogenous and exogenous acids.
Dilute acid - A dillute acid is an acid which has water in a ratio of 90:10 90 water and 10 acid.
Indicator - a substance (as a dye) used to show visually (as by a change in color) the condition of a solution with respect to the presence of a particular material
Neutralization - the reaction of an acid and a base forming a salt and water.
Acid rain - rainfall made so acidic by atmospheric pollution that it causes environmental harm, chiefly to forests and lakes. The main cause is the industrial burning of coal and other fossil fuels, the waste gases from which contain sulphur and nitrogen oxides which combine with atmospheric water to form acids.
Why is lifting a box off the ground considered work but carrying a box is not ?
Answer:
In this case the gravitational force is conservative, but the force you exert is not. So, as you lift the box, the work done by non-conservative forces (you) is not zero, and as a result, the total energy of the box increases.
But, Lifting a box is not scientifically considered "work"
Explanation: You do no work against gravity because you are not moving any distance (more accurately displacement) in the direction of the force i.e. the force and displacement are perpendicular once you have lifted the boxes. As work done = force x displacement parallel to the force, no work is done.
Hope This Helps :)
HELP PLSS!!! I want a answer by the end of the day pls!!! Determine if the following statement is true or false and explain why: Heating a material will not destroy matter.(1 point)
True. Heating will always convert some matter into another substance, but the Law of Conservation of Mass states that matter may not be destroyed.
True. Heating will always convert some matter into another substance, but the Law of Conservation of Mass states that matter may not be destroyed.
False. Heating will always convert some matter into another substance, and this process results in matter being destroyed in order to form the new substance.
False. Heating will always convert some matter into another substance, and this process results in matter being destroyed in order to form the new substance.
True. Heating may convert some matter into another substance, but the Law of Conservation of Mass states that matter may not be destroyed.
True. Heating may convert some matter into another substance, but the Law of Conservation of Mass states that matter may not be destroyed.
False. Heating may convert some matter into another substance, and this process results in matter being destroyed in order to form the new substance.
Answer:
True. Heating may convert some matter into another substance, but the Law of Conservation of Mass states that matter may not be destroyed.
Explanation:
the answer is C
Calculate the molality of chloride ions in an aqueous solution of magnesium chloride in which the mole fraction of magnesium chloride is 0.0400 .
The molality of chloride ions is 4.63kg/L
Data;
Mole Fraction = 0.0400Molality of Chloride ions = ?Molality of Chloride ionsMole Fraction of MgCl2 = 0.04
The sum of mole fraction = 1
Mole fraction of water = 1 - 0.04 = 0.96
since the total number of moles = 1
Number of moles of MgCl2 = mole fraction * total number of moles
Number of moles of MgCl2
[tex]0.04 * 1 = 0.04 moles[/tex]
Number of moles of water =
[tex]0.96 * 1 = 0.96 moles[/tex]
1 moles of MgCl2 = 2 moles of Chloride ions
Number of moles of chloride ions
[tex]2 * 0.04 = 0.08 moles[/tex]
Number of moles of water = 0.96moles
mass of water = molecular weight * number of moles
mass of water =
[tex]18 * 0.96 = 17.28g[/tex]
let's convert this to kilogram
[tex]1000g = 1kg\\17.28g = x\\x = 0.01728kg\\[/tex]
The molality of the ions in the solution is
[tex]M = \frac{mass of solute}{volume of solution} \\M = \frac{0.08}{0.01728} =4.63 kg/L[/tex]
The molality of chloride ions is 4.63kg/L
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If the half-life of hydrogen-1 is 12 years, how much is left over of an original sample of 40g after 36 years?
The amount remaining after 36 years is 5 g
How to determine the number of half-lives Half-life (t½) = 12 yearsTime (t) = 36 years Number of half-lives (n) =?n = t / t½
n = 36 / 12
n = 3
How to determine the amount remaining Original amount (N₀) = 40 gNumber of half-lives (n) = 3Amount remaining (N) = ?N = N₀ / 2ⁿ
N = 40 / 2³
N = 40 / 8
N = 5 g
Therefore, the amount remaining after 36 years is 5 g
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Which term refers to a substance that is formed in one step of a reaction mechanism and consumed in a subsequent step of the reaction mechanism?
catalyst
reagent
extracellular protein
reaction intermediate
Answer:
: B, if it is produced in an earlier step. Which term refers to a substance that is formed in one step of a reaction mechanism and consumed in a subsequent step of the reaction mechanism? D: reaction intermediate
Explanation:
pa brainlyes po kailangan lang talaga
Answer:
its D
Explanation:
trust
Atoms with different numbers of neutrons in their nucleus are:.
Answer: They are referred to as isotopes, which are a form of an element that has different numbers of neutrons in their nucleus.
Which scientist researched and described the results of genetic crosses?
Question 1 options:
Alfred Wegner
Gregor Mendel
Marie Curie
Santa Clause
Gregor Mendel researched and described the results of genetic crosses. He is considered the father of genetics.
Who was Gregor Mendel?Gregor Mendel was a botanist who made different genetic crosses using pea plants as a model organism.
Gregor Mendel observed as phenotypic traits were transmitted to the pea descendence in the F1 and F2 generation.
Gregor Mendel developed fundamental laws in genetics such as independent assortment and segregation.
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Oxygen ENTERS the body through the...
1.The circulatory system
2.The Digestive system
3.The respiratory system
4. The cells in the body
Answer:
Respiratory System
Explanation:
It connects with the lungs. The oxygen enters the body through the capillaries which are a part of the respiratory system.
A 500g piece of Aluminum has a temperature increase of 7 degrees. The specific heat of Aluminum is 0.900 J/gC. If you were using q = m c ∆T to find the amount of heat produced, which value would you plug in for "m"?
500 g
0.900 j/gC
3150 j
7 degrees
Answer:
is it 500 g
Explanation:
cause m stands for mass
To find the amount of heat produced, the value of m which we plug is 500 grams.
How do we calculate the amount of heat?Amount of heat absorbed or released during any chemical change will be calculated as:
Q = mc∆T, where
Q = absorbed or released heat
m = mass of substance
c = specific heat of substance
∆T = change in temperature
So, according to question to calculate energy in place of m we will put the given mass of aluminum which is equal to 500g.
Hence required value of m is 500g.
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One whale sang to communicate with another whale. The song's sound wave traveled 4,900 meters directly toward the second whale at a constant velocity. The sound wave took 3.5 seconds to move that distance. What was the sound wave's velocity?
solve B in a complete combustion pleaseee
Answer:
2 C2H2 + 5 O ---> 4 CO2 + 2 H2O
Explanation:
combustion reactions always end with CO2 + H2O
and you can use this website to balance out equations when you're stuck
https://en.intl.chemicalaid.com/tools/equationbalancer.php?equation=C2H2+%2B+O2+%3D+CO2+%2B+H2O
Donna is drinking alcohol with her friend Allan. They have both consumed the same amount of alcohol so far. It is likely that Donna's blood alcohol concentration (BAC) will be about a. the same as Allen's. b. 10% lower than Allen's. c. 10% higher than Allen's.
It is likely that Donna's blood alcohol concentration (BAC) will be about
10% higher than Allen's.
What is Concentration?This is defined as the abundance of a constituent divided by the total
volume of a mixture.
During drinking, the concentration of alcohol is dependent on a lot of
factors such as the internal constituent of the body which is why Donna
will most likely have a higher alcohol concentration.
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the radio waves from your cell phone go through the air and are received by a ??
Answer:
An antenna
Explanation:
Radio waves are received by antennas
The type of bond that links the amino group of one amino acid to the acid group of another is a(n) _____ bond.
Answer: peptide
The type of bond that links the amino group of one amino acid to the acid group of another is a(n) peptide bond.
10. The energy in a spinning ferris wheel
a. Potential energy
b. Kinetic energy
Answer:
kinetic energy is the right answer
Answer: the answer is B
Explanation: its a spinning Ferris wheel meaning its in motion
Trevor was able to collect what appeared to be blood and sweat from a kitchen counter. What type of evidence does this BEST represent
A. trace evidence
B. biological evidence
C. ammunitions evidence
D. impression evidence
Answer:
Biological Evidence
Explanation:
Both blood and sweat are fluids within the body, therefore, both are biological substances.