Answer:
If iron, Fe, and oxygen, O2, are in contact at high enough temperatures (and with plenty of oxygen around), the grey or reddish compound that forms is called iron(III) oxide with the formula Fe2O3
Explanation:
Iron rusts. We all know that. But the chemical reactions behind rust are surprisingly complicated! We will return to them at the end of the course when we discuss corrosion (see section 11.6 in the text). Here, we focus simply on the main compounds formed between iron and oxygen. That there is more than one may surprise you. That there are not an infinite number of them (and in fact, there almost is, as well shall see!) is an example of the law of definite proportion, an idea so central to chemistry it is almost taken for granted today.
If an atom contains 11 protons and 12 neutrons, its ATOMIC NUMBER is: a 1 b 11 c 12 d 23
Answer:
B)11
Explanation:
The atomic number is the number of protons and electrons in an atom!!
HOPE THIS HELPS!!!!!!
Students are given a solid sample and asked to determine whether the sample is an element, compound, or mixture. One student observes that the sample is:
made up of particles of different colors, sizes, and shapes
some particles are softer than others
some shine while others appear dull
What can the students conclude about their sample?
It is an element.
It is a compound.
It is a homogeneous mixture.
It is a heterogeneous mixture.
Answer:
Compound
Explanation:
The sample given to the students is a mixture.
A mixture is composed of substances that are not chemically combined together. The components of a mixture all retain their individual properties. So in a mixture, we can easily notice the individual components if the mixture is heterogeneous.
Clearly, the students were given a heterogeneous mixture because one student observed that the sample is;
made up of particles of different colors, sizes, and shapes some particles are softer than others some shine while others appear dullBased on these observations, other students can agree that the sample is a mixture.
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Calculate the wavelength of light with an energy of 3.60x10^-19 J *
Explanation:
from E = mc^2 and de Broglie wavelength=h/mc
combine the eqns with respect to m(considering the body is moving with the speed of light(c))
then
E= hc/de Broglie wavelength
since, c= 3× 10^ 8
h= 6.626 × 10^ -34 and E is given, substitute the values.
sorry I don't have my calculator.
3. How does the independent variable (IV)
differ from the dependent variable (DV)?
Answer:
Independent variable in independent where the dependent variable relays on the independent one.
Explanation:
Look in the names and above.
Why is it difficult to hold and keep liquids like water in your hand? Guys please help
Answer:
Molecules move freely around since they don't have a definite shape. This is the reason water stays liquid and couldn't be gripped.
Which of the following is not an example of temperature abuse ?
Hector went to the grocery store by heading due north at 3 m/s, then turning east and continuing at
the same speed for another three blocks. Which of the following is true about Hector's velocity?
A. Hector's velocity did not change because his direction did not change.
B. Hector's velocity changed because his speed changed.
C. Hector's velocity changed because his direction changed.
D. Hector's velocity did not change because his speed did not change.
Hector's velocity changed because his direction changed.
Velocity refers to the distance covered per unit time in a specified direction while speed is the distance covered per unit time without taking the direction into account.
We must note that Hector's direction changed. since magnitude and direction are both considered when discussing velocity, then Hector's velocity changed because his direction changed.
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A student dissolves 10,3 g of sodium chloride(NaCl) in 250 g of water in a well-insulated open cup. She then observes the temperature of the water fall from 23.0 °C to 22.2 °C over the course of 3 minutes. Use this data, and any information you need from the ALEKS Data resource,
NaCl (s) rightarrow Na+ (aq) + Cl- (aq)
You can make any reasonable assumptions about the physical properties of the solution. Note for advanced students: it's possible the student did not do the experiment carefully, and the values you calculate may not be the same as the known and published values for this reaction.
1. Is this reaction exothermic, endothermic, or neither?
2. If you said the reaction was exothermic or endothermic, calculate the amount of heat that was released or absorbed by the reaction in this case.
3. Calculate the reaction enthalpy delta Hrxn per mole of NaCl.
Answer:
1
The reaction is exothermic
2
[tex]H = -1.1 \ KJ[/tex]
3
[tex]\Delta H_{rxn} = -6.24 \ KJ/ mol[/tex]
Explanation:
From the question we are told that
The mass of the sodium chloride is (NaCl ) is [tex]m_s = 10.3 \ g[/tex]
The mass of water is [tex]m_w = 250 \ g[/tex]
The initial temperature is [tex]T_i = 23^oC[/tex]
The temperature after 3 minutes is [tex]T_3 = 22.2 ^oC[/tex]
The time taken for temperature to fall is t = 3 minutes
The reaction is
[tex]NaCl_{ (s)} \rightarrow Na^+ _{(aq)} + Cl^-_{ (aq)}[/tex]
The reaction is exothermic because the temperature fell
Generally the mass of the solution is mathematically represented as
[tex]M = m_w + m_s[/tex]
=> [tex]M = 250 + 10.3 [/tex]
=> [tex]M = 260.3 \ g [/tex]
Gnerally the heat energy released from the solution is mathematically represented as
[tex]H = M * C_s * (T_3 - T_i)[/tex]
Here [tex]C_s[/tex] is the specific heat of solution which for this question we would assume it is the specific heat of water which has a value of
[tex]Cs = C_w = 4.18 J/g^oC[/tex]
So
[tex]H = 260.3 * 4.18 * (22- 23)[/tex]
[tex]H = -1088.054 \ J[/tex]
[tex]H = -1.088054 \ KJ[/tex]
[tex]H = -1.1 \ KJ[/tex]
Generally the number of moles of NaCl is mathematically represented as
[tex]nNaCl = \frac{m_s}{zNaCl}[/tex]
Here [tex]zNaCl[/tex] is the molar mass of NaCl and the value is
[tex]zNaCl = 58.44 \ g/mol[/tex]
So
[tex]nNaCl = \frac{10.3}{58.44 }[/tex]
=> [tex]nNaCl = 0.1762 \ moles[/tex]
Generally reaction enthalpy is mathematically represented as
[tex]\Delta H_{rxn} = \frac{H}{nNaCl}[/tex]
[tex]\Delta H_{rxn} = \frac{-1.1}{0.1762 }[/tex]
[tex]\Delta H_{rxn} = -6.24 \ KJ/ mol[/tex]
Consider the reaction: CH3COOH(aq)+H2O(l)⇌H3O+(aq)+CH3COO−(aq) K=1.8×10−5 at 25∘C Part A If a solution initially contains 0.265 molL−1 CH3COOH, what is the equilibrium concentration of H3O+ at 25∘C?
Answer:
[tex][H_3O]^+=2.18x10^{-3}M[/tex]
Explanation:
Hello.
In this case, for the given ionization chemical reaction of acetic, the equilibrium expression is:
[tex]Ka=\frac{[H_3O^+][CH_3COO^-]}{[CH_3COOH]}[/tex]
Since aqueous species are considered only. Next, by introducing the reaction extent [tex]x[/tex] based on the ICE table, in which it equals the concentration of both H3O+ and CH3COO-, we can also write:
[tex]1.8x10^{-5}=\frac{x*x}{0.265M-x}[/tex]
As the acid ionization constant is small in comparison to 0.265 M, we can make an approximation to compute [tex]x[/tex] as shown below:
[tex]1.8x10^{-5}=\frac{x*x}{0.265M}\\\\x=\sqrt{1.8x10^{-5}*0.265}= 2.18x10^{-3}M[/tex]
It means that the concentration of H3O+ is:
[tex][H_3O]^+=2.18x10^{-3}M[/tex]
Best regards.
A solution of acetic acid (Ka = 1.8 × 10⁻⁵) with an initial concentration of CH₃COOH of 0.265 mol/L has an equilibrium concentration of H₃O⁺ at 25 °C of 2.18 × 10⁻³ M.
Let's consider the reaction for the acid ionization of acetic acid.
CH₃COOH(aq) + H₂O(l) ⇌ H₃O⁺(aq) + CH₃COO⁻(aq)
The acid ionization constant (Ka) is 1.8 × 10⁻⁵ and the initial concentration of the acid (Ca) is 0.265 mol/L.
Considering that it is a weak monoprotic acid, we can calculate the equilibrium concentration of H₃O⁺ at 25 °C using the following expression.
[tex][H_3O^{+} ]= \sqrt{Ka\times Ca } = \sqrt{1.8\times 10^{-5} \times 0.265 } = 2.18 \times 10^{-3} M[/tex]
A solution of acetic acid (Ka = 1.8 × 10⁻⁵) with an initial concentration of CH₃COOH of 0.265 mol/L has an equilibrium concentration of H₃O⁺ at 25 °C of 2.18 × 10⁻³ M.
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Which characteristic is expected of a mineral that crystallizes from lava at Earth’s surface?
large crystals
small crystals
magnetic crystals
hexagonal crystals
Answer:
Small Crystals
Explanation:
Answer:
the answer is B
Explanation:
Consider the following isotopic abundance data for argon (Ar) and silicon (Si):
Argon Isotope Isotopic Molar Mass 36 Ar 35.96755 g/mol Ar 37.96272 g/mol 40 Ar 39.96240 g/mol Abundance 0.337% 0.063% 99.600% Silicon Isotope Isotopic Molar Mass 25 Si 27.97693 g/mol 29 Si 28.97649 g/mol 30 Si 29.97376 g/mol Abundance 92.23% 4.67% 3.10%
Use the data to calculate the atomic masses of naturally occurring argon and silicon.
b) Calculate the number of atoms in 78.2 g of naturally occuring Si.
c) 42Ar is one of the longest lived radioactive isotopes of Argon. Mass spectroscopy data yields the following ratio of the mass of 42Ar to 40Ar: Mass of 42Ar Mass of 40Ar = 1.05006 use this ratio to find the atomic mass of 42Ar.
2. Pantoprazole, first sold under the brand name Protonix, is used for short-term treatment of erosive esophagitis associated with gastroesophageal reflux disease (GERD). The chemical formula for pantoprazole is C16H15F2N3O4S a) What is the molar mass of pantoprazole? b) How many molecules are in a 0.078 g sample of panotprazole?
Answer:
Explanation:
Molar mass of Argon
= 35.96755 x .00337 + 37.96272 x .00063 + 39.96240 x .99600
= .12121 + .0239165 + 39.80255
= 39.95
Molar mass of silicon
27.97693 x .9223 + 28.97649 x .0467 + 29.97376 x .0310
= 25.803 + 1.35320 + .929
= 28.08
b )
No of atoms of Si in 78.2 g = 78.2 x 6.02 x 10²³ / 28.08
= 16.76 x 10²³ .
c )
42 Ar / 40 Ar = 1.05006
42 Ar / 39.95 = 1.05006
42Ar = 41.95
2 )
C₁₆H₁₅F₂N₃O₄S
Mol weight = 16 x 12 + 1 x 15 + 2 x 19 + 3 x 14 + 4 x 16 + 32
= 192 + 15 + 38 + 42 + 64+ 32
= 383
No of molecules = .078 x 6.02 x 10²³ / 383
= 1.226 x 10²⁰ molecules .
Answer:
It's too short. Write at least 20 characters to explain it well.
Explanation:
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Chlorine is made up of 75.78% 35cl and 24.22% 37 cl. The atomic mass of 35 CL is 34.969 amu. The atomic mass of 37 CL is 36.966 amu. What is the average atomic mass of a sample of chlorine?
35.453 amu is the correct answer
Which is most likely a covalent compound?
LiF
MgS
NH3
CaCl2
Answer:
NH3 is the most likely covalent compound
Explanation:
Other Choices are:
LiF- Ionic compound
MgS- ionic compound
CaCl2- ionic compound
The most likely to have a covalent bond is NH₃. The correct option is c. covalent bonds are the strongest bonds among all.
What are covalent bonds?A covalent bond is formed between two atoms by the mutual sharing of one or more pairs of electrons. The two atomic nuclei attract these electrons at the same time. When the difference in electronegativities of two atoms is too tiny for electron transfer to produce ions, a covalent bond occurs.
The unequal sharing of electrons between the combining atoms results in the formation of a polar covalent bond. The equal sharing of electrons between the combining atoms results in the formation of a non-polar covalent bond.
LiF- Ionic compound
MgS- ionic compound
CaCl₂- ionic compound
Therefore, the correct option is c, NH₃.
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An element with 7 valence electrons will most likely
Answer:
An element with 7 valence electrons will most likely be a halogen and gain an electron
Explanation:
The element with 7 valence electrons is a halogen. Halogen group contains fluorine, chlorine, bromine, iodine and astatine.
What are halogens?Halogens are 17th group elements in periodic table. They are gases and shows high electronegativity. Halogens are p block elements.
The group number in periodic table is given assigned by adding 10 to the number of valence electrons if the no of valence electrons is 3 or more. Elements containing 1 or 2 valence electrons are in group 1 and 2 respectively.
Thus, if the number of valence electron 7 then, the element is in group 17 and it is a halogen.
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no one ever helps me ☹️ can y’all look at my questions !?
Answer:
[tex]Hope this helps you[/tex] A typical atom consists of three subatomic particles: protons, neutrons, and electrons (as seen in the helium atom below). Other particles exist as well, such as alpha and beta particles (which are discussed below). The Bohr model shows the three basic subatomic particles in a simple manner. Most of an atom's mass is in the nucleus—a small, dense area at the center of every atom, composed of nucleons. Nucleons include protons and neutrons. All the positive charge of an atom is contained in the nucleus, and originates from the protons. Neutrons are neutrally-charged. Electrons, which are negatively-charged, are located outside of the nucleus. [tex]Enjoy your day[/tex]
Explanation:
Answer:
Atoms are the fundamental building blocks of all matter and are composed of protons, neutrons, and electrons. Because atoms are electrically neutral, the number of positively charged protons must be equal to the number of negatively charged electrons. Since neutrons do not affect the charge, the number of neutrons is not dependent on the number of protons and will vary even among atoms of the same element.
Explanation:
hope it helps
What is the minimum number of significant digits in 828,000,000
Answer:
Answer:
Number of Significant Figures: 3
The Significant Figures are 8 2 8
Explanation:
you welcome
What is an organ? List five (5) examples of organs?
Answer:
Here are all of the organ systems with some examples of organs found in each system:
Integumentary (skin, hair, nails)
Skeletal (bones)
Muscular (smooth, cardiac, and skeletal muscles)
Circulatory (heart, arteries, veins)
Respiratory (lungs, diaphragm, larynx)
Digestive (stomach, intestines, liver)
Explanation:
Zachary adds 26.64 g to 12.557 g. How many significant figures should his answer have?
two
three
four
five
This answer should have four signifigant features
Explanation:
I had this on a test and got it right :D
what are the real primary colors
Answer:
red, yellow, blue are the 3 main primary colors
Which phase has the greatest structure
Answer:
The answer is D
Explosion:
it depends on the solid,liquid,gas and the tempcher
A student is trying to calculate the density of a ball. She already knows the mass, but she needs to determine the volume as well. Which of the following formulas can be used to calculate the volume of the ball?
Group of answer choices
V equals four-thirds times pi times r cubed
V equals one-third times pi times r squared times h
V = s3
V = πr2h
Answer:
V equals four-thirds times pi times r cubed
Explanation:
Volume = a³ , where a is length of each side. Volume = l × w × h , where l is length, w is width and h is height. Volume = 4/3 πr³ , where r is the radius. Volume = πr²h , where r is the radius and h is the height.
If you squeeze a foam pillow, what kind of energy are you increasing in the foam?
Group of answer choices
Nuclear energy
Sound energy
Chemical energy
Elastic energy
Answer:
elastic energy
Explanation:
If you squeeze a foam pillow, elastic energy is increasing in the foam. Therefore, option D is correct.
What is elastic energy?Elastic energy can be described as the mechanical potential energy stored in the physical system as it is subjected to elastic deformation by work performed upon it. Elastic energy takes place when objects are impermanently compressed, stretched, or deformed.
Elasticity theory develops formalisms for the mechanics of solid bodies and materials. The elastic potential energy can be used in mechanical equilibrium. The energy can be described as potential as it will be transformed into other forms of energy.
[tex]{\displaystyle U={\frac {1}{2}}k\,\Delta x^{2}}[/tex]
Forces applied to elastic transfer energy into the material yield energy to its surroundings and can recover its original shape. Materials have limits to the degree of distortion can without breaking or irreversibly altering their internal structure.
The elastic energy of a substance can be defined as the static energy of configuration. It refers to the energy stored by changing the interatomic distances between nuclei.
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Which type of microscope can be used to view atoms
Answer:
transmission electron microscope
Explanation:
Answer:
Scanning tunneling microscope
Explanation:
An organic solvent has a density of 1.31 g/mL. What volume is occupied by 57.5 g of the liquid?
mL
Answer:
The answer is 43.89 mLExplanation:
The volume of a substance when given the density and mass can be found by using the formula
[tex]volume = \frac{mass}{density} \\[/tex]
From the question
mass = 57.5 g
density = 1.31 g/mL
We have
[tex]volume = \frac{57.5}{1.31} \\ = 43.89312977...[/tex]
We have the final answer as
43.89 mLHope this helps you
What Types of food molecules make up lettuce
a chemist has a jar containing 388.2 g of iron fillings. how many moles of iron does the jar contain?
Carbon -11 is a radioactive isotope of carbon. It’s half life is 20 minutes. What amount of the initial mass of 70.0g of C -11 atoms in a sample will be left after 80 minutes
Answer:
4.38g
Explanation:
70.0/2 = 35g - 20 mins
35/2 = 17.5g - 40 mins
17.5/2 = 8.75g - 60 mins
8.75/2 = 4.375g - 80 mins
4.375 g of the carbon 11 would be remaining after 80 minutes.
Half life is the time taken for a substance to decay to half of its original value. It is given by:
[tex]N(t)=N_o(\frac{1}{2})^{\frac{t}{t_\frac{1}{2} } } \\\\\\Where\ t_\frac{1}{2}\ is\ half\ life,N_o\ is\ original\ amount,t\ is\ time,N(t)\ is\\amount\ remaining\\\\\\Given\ that\ N_o=70,t_\frac{1}{2}=20,t=80, hence:\\\\N(t)=70(\frac{1}{2} )^\frac{80}{20}=4.375\ g[/tex]
Therefore, 4.375 g of the carbon 11 would be remaining after 80 minutes.
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which statement accurately describes the reactants of a reaction?
Answer:
Option (B) is the correct answer.
Explanation:
Reactants are the species which are present on the left hand side of a chemical equation.
On the other hand, products are the species which are present on the right hand side of a chemical equation.
For example,
Here, NaCl and H_{2}O are the reactants whereas NaOH and HCl are the products.
This also means that products are the new substances which are formed.
Thus, we can conclude that new substances that are present at the end of a reaction accurately describes the products of a reaction.
the one that accurately describes the products of a reaction is : B. new substances that are present at the end of a reaction
For example the process of photosynthesis transform CO2 and other nutrients into O2 and H2O
Answer:
I think its substances that are used up
Explanation:
A small bottle of water is left on the shore of a very large lake on an extremely cold winter night. What is most
likely to be observed the next morning? A). Both the lake and the bottles of water have become solid. B). The bottle of water has become solid but the lake has not. C). The lake has become solid but the bottle of water has not. D). Neither the bottle of water or the lake have become solid.
Answer:
A
Explanation:
Because it is a cold winter night making the lake freeze and the bottle is already solid.
. The center of the atom is called the
(10 Points)
O nucleus
O protons
O electrons
O
neutrons
Answer:
Protons I think. I might be wrong but I think its Protons
Answer:
the nucleus is the center of atoms and its made of of protons and neutrons
Explanation: