Answer:
Place 20.0 g NaOH(s) in a flask and dilute to 1.00 L with water.
Explanation:
A 2.49 g sample of aniline (C6H5NH2, molar mass = 93.13 g/mol) was combusted in a bomb calorimeter with a heat capacity of 4.25 kJ/°C. If the temperature rose from 29.5°C to 69.8°C, determine the value of ΔH°comb for aniline.
The value of delta H° for aniline = 6415 Kj/mol
calculation
Step 1: find heat
Q (heat) = C (specific heat capacity) x ΔT (change in temperature)
C= 4.25 kj/c°
ΔT = 69.8-29.5 = 40.3 c°
Q= 4.25 kj/c x 40.3 c = 171.28 kj
Step 2: find the moles of aniline
moles = mass/molar mass
= 2.49 g/ 93.13 g/mol =0.0267 moles
Step 3: find delta H
171.28 kj/0.0267 mol = 6415 kj/mol
since the reaction is exothermic delta H = 6415 Kj/mol
Answer:
-6.41x10^3
Explanation:
2.49 is 3 significant figures, so your answer should reflect that. Since heat is lost to the surroundings, the reaction is exothermic, and the answer should be negative.
QUESTION TO
What would I have to change to have a lunar eclipse happen every month?
You would have to fix the tilt of the Moon's orbit and make the Moon orbit planet Earth within the same plane that the Earth orbits the Sun.
What is a lunar eclipse?A lunar eclipse can be defined as a phenomenon which occurs when the planet Earth comes in between the Moon and the Sun, thereby causing the Earth to cover the Moon with its shadow.
In order to have a lunar eclipse occur every month, you would have to fix the tilt of the Moon's orbit and make the Moon orbit planet Earth within the same plane that the Earth orbits the Sun, so as to block any ray of sunlight from reaching the Moon.
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Three students are given a 200g object to weigh on a balance and record the following masses: 150g, 151g 150g. What can be said about the accuracy and precision of the balance?
Look at the question marks between zinc (Zn) and arsenic (As) . At the time no elements were known with atomic weights between 65.2 and 75
Mendeleev positioned elements in the periodic table in increasing order of their atomic numbers, such that elements having identical chemical properties and characteristics plunge into the same group.
What is Mendeleev's periodic table?Mendeleev's periodic table may be defined as a collection of elements in an increasing atomic mass hierarchy in a table arrangement, such that it reminisces resemblances and manias according to their chemical properties and characteristics.
Mendeleev found that two elements existed between atomic weights 65.2 and 75 because he comprehended especially pleasingly that the possessions of the elements were more comparable and closer to this degree.
He also anticipated having other elements that would have their possessions comparable to these other elements.
Therefore, he departed a void for these two elements in the periodic table until they were ultimately found in their real existence.
The complete question is as follows:
Look at the two question marks between zinc (Zn) and arsenic (As). At the time, no elements were known with atomic weights between 65.2 and 75. But Mendeleev predicted that two elements must exist with atomic weights in this range. What led Mendeleev to predict that two undiscovered elements existed in that range?
Therefore, it is well described above.
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Which of the following is non polar covalent bond?
electronegativities:
C = 2.5, H = 2.1, P = 2.1, Cl = 3.0, N = 3.0, O = 3.5
N -O
N-Cl
P-O
H-Cl
Answer:
N-Cl
Explanation:
Look at the chart below. Since N-Cl bond has a electronegativity difference of (3.0-3.0) zero, they are non-polar.
How many moles are in 24 g of carbon
Answer:
[tex]\fbox {2 moles}[/tex]
Explanation:
Relation between grams of Carbon and moles :
[tex]\fbox {12 g Carbon = 1 mole}[/tex]
Multiply both sides by 2 :
⇒ 1 x 2 moles = 12 x 2 g
⇒ 2 moles = 24 g
Hey there.
Explain JJ Thomson's model.
Thomson discovered the electron, the first subatomic particle. In 1904, Thomson proposed atomic model where electrons are embedded within spherically distributed, positive charge (so-called "plum pudding" model).
J.J. Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson proposed the plum pudding model of the atom, which had negatively-charged electrons embedded within a positively-charged "soup."
☆...hope this helps...☆
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7. Name the representative particle (atom, molecule, ion or formula unit) of Radon
Answer: A representative particle can be an atom, and an ion. a molecule, or a formula unit.
Explanation:
A representative particle is the smallest unit in which a substance naturally exists. For the majority of elements, the representative particle is the atom. Iron, carbon, and helium consist of iron atoms, carbon atoms, and helium atom, respectively.
Radon is a naturally occurring radioactive gas that is odorless and tasteless.
Atoms-the smallest particle of an element
Ions-atoms with positive or negative charges.
Molecules- two or more covalently bonded atoms.
Formula units- the simplest ratio of ions that make up an ionic compound.
Need answer asap!! Molecules in the solid state
A) transfer heat to neighboring molecules by convection
B) have no motion
C) have no internal energy
D) vibrate in fixed positions
Answer:
c, have no internal energy
Compared to infrared radiation, an electromagnetic wave that has a lower frequency will also have a ________.
longer wavelength and lower speed
longer wavelength and equal speed
shorter wavelength and lower speed
shorter wavelength and equal speed
Compared to infrared radiation, an electromagnetic wave that has a lower frequency will also have a longer wavelength and equal speed
What is Electromagnetic wave ?Electromagnetic waves or EM waves are waves that are created as a result of vibrations between an electric field and a magnetic field.
It can be also defined as waves are composed of oscillating magnetic and electric fields.
One important feature fo electromagnetic radiation is that all have the same speed in vacuum, c, in vacuum, which is the speed of light.
Since, the speed, wavelength and frequency of the waves are related you can infere any of them when the other two are known.
The equation is:
speed = frequency × wavelength
s = ν × λ
c = ν × λ . . . for the specific case of electromagnetic radiation
That inverse relation between frequency and wavelength, where the speed is the constant, shows that the lower the frequency the longer the wavelength.
Therefore, the correct statment is that an an electromagnetic wave that has a lower frequency will also have a longer wavelength and equal speed (option B).
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What is the freezing point of an aqueous suger (C12H22O11) solution that boils at 110C°?
Sucrose doesn't show appreciable dissociation in water, so i≈1 in this case. by extension, −7.3°C is the approximate freezing point of this solution.
What is the freezing point?The temperature at which a liquid solidifies.
Sucrose doesn't show appreciable dissociation in water, so i≈1 in this case. by extension, −7.3°C is the approximate freezing point of this solution.
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If 13.0 g of MgSO4⋅7H2O is thoroughly heated, what mass of anhydrous magnesium sulfate will remain?
6.349 g mass of anhydrous magnesium sulfate will remain.
What are moles?A mole is defined as 6.02214076 × 1023 of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.
Molar mass MgSO₄.7 H₂O = 246.52 g/mol
[tex]Moles =\frac{mass}{molar \;mass}[/tex]
[tex]Moles =\frac{13.0 g}{246.52}[/tex]
0.0527 moles
Molar mass MgSO₄ = 120.4 g/mol
Mass of anhydrous magnesium sulfate :
( 0.0527 x 120.4 ) => 6.349 g
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What type of reaction is represented by the following equation?
Mg(OH)2 (aq) + 2 HCl (aq) --> MgCl2 (aq) + 2 H2O (l)
Answer: Double replacement reaction
Explanation:
Identify the branch of chemistry being described.
a. _______________ study of the behavior and changes in matter including energy transfers, reaction mechanisms, and reaction rates.
b. _______________ study of compounds and chemicals containing carbon, which include pharmaceuticals, drugs, and plastics.
c. _______________ study of the components and composition of matter, including food nutrients, and quality control.
d. _______________ study of matter and processes that occur in biological organisms, including metabolism and fermentation.
Answer:
a. Physical Chemistry
b.Organic Chemistry
c.Food analysis, a very important branch of analytical chemistry
d. Biochemistry
Explanation:
number 3 pls and thank u
The statement which is not true is as follows:
The repulsive force between electrons on different atoms does not matter at all.Thus, the correct option is C.
What is Equilibrium?An equilibrium may be defined as the condition in which both the reactants and products are present in concentrations that have no additional propensity to alter with time so that there is no noticeable transformation in the possessions of the system.
The causation of repulsive force was thought to be made by the overlap of atomic orbitals and in between the electrons of diverse atoms, it matters a lot.
The equilibrium distance between nuclei of two covalently bonded atoms is called the bond length of that atom. It is the atomic separation at equilibrium.
Equilibrium occurs when the attractive and repulsive forces neglected the effect of each other in a specific state.
Therefore, it is well described above.
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Which of the following is a covalent compound?
NF3
KBr
CuO
FeCI3
What types of bonds and atoms are in the molecule shown below?
H₂C
C=C
H
CH₂-CH3
H
O A. Double bonds, triple bonds, carbon atoms, and hydrogen atoms
O B. Double bonds, triple bonds, carbon atoms, and helium atoms
OC. Single bonds, double bonds, carbon atoms, and hydrogen atoms
OD. Single bonds, double bonds, carbon atoms, and helium atoms
The types of bonds and atoms in the molecule shown below are C. Single bonds, double bonds, carbon atoms, and hydrogen atoms.
How many bonds can carbon form?Carbon can only form a bond with a maximum of 4 other molecules.
We have been given a molecule
H₂C CH₂-CH3
C=C
H H
In the given figure we can see that the molecule includes one double bond and other are single bonds.
Thus, The types of bonds and atoms in the molecule shown below are C. Single bonds, double bonds, carbon atoms, and hydrogen atoms.
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0.160g of Mg is equal to how many moles Mg
The 0.160 grams of Mg is equal to 0.00658 moles of Magnesium (Mg).
Given,
Mass of Mg, m=0.160g
The atomic mass of Mg is 24.31 g.
The number of moles can be represented as the ratio of the given mass of the atom/molecule to the Atomic/Molar mass of the atom/molecule.
Atomic mass can be defined as the mass of the one mole of an atom and Similarily, molecular mass can be defined as the mass of one mole of a molecule.
Number of moles, n=Given mass/Molar mass
n=0.160g/(24.31g/mol)=0.00658 moles
Hence, the 0.160 grams of Magnesium (Mg) is equal to 0.00658 moles of Magnesium (Mg).
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When 50.0 g iron(III) oxide reacts with carbon monoxide, 32.5 g iron is produced. What is the percent yield of the reaction?
Fe2O3(s)+3CO(g)→2Fe(s)+3CO2(g)
Answer:
92.9%
Explanation:
You have been given the actual yield of the reaction. First, you need to find the theoretical yield of the reaction. To do this, you need to (1) convert grams Fe₂O₃ to moles Fe₂O₃ (via molar mass from periodic table values), then (2) convert moles Fe₂O₃ to moles Fe (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles Fe to grams Fe (via molar mass).
Once you have found the theoretical yield, you need to use the percent yield equation to calculate the final answer. This number should have 3 sig figs to match the given values.
(Step 1)
Molar Mass (Fe₂O₃): 2(55.845 g/mol) + 3(15.998 g/mol)
Molar Mass (Fe₂O₃): 159.684 g/mol
1 Fe₂O₃(s) + 3 CO(g) ---> 2 Fe(s) + 3 CO₂(g)
Molar Mass (Fe): 55.845 g/mol
50.0 g Fe₂O₃ 1 mole 2 moles Fe 55.845 g
-------------------- x ------------------ x --------------------- x ---------------- = 35.0 g Fe
159.684 g 1 mole Fe₂O₃ 1 mole
(Step 2)
Actual Yield
Percent Yield = --------------------------- x 100%
Theoretical Yield
32.5 g Fe
Percent Yield = ---------------------- x 100% = 92.9%
35.0 g Fe
b. Describe hydrogen bonding. (1 point)
why is it important to convert currency units from one type to another chemistry
easy to compare
easy in calculation
adjust to units commonly used in certain places
what is the new concentration of A if 7.7 ml of a .10 M solution of A is mixed with 18.3 mL of .20 M solution B and an additional 11.7 ml water?
Answer:
0.12 M
Explanation:
To find the new concentration, you need to (1) find the moles of Solution A (via the molarity equation), then (2) find the moles of Solution B, then (3) combine all of the moles and volumes, and then (4) calculate the new molarity. The final answer should have 2 sig figs to reflect the lowest amount of sig figs in the given values.
Solution A:
7.7 mL / 1,000 = 0.0077 L
Molarity = moles / volume
0.10 M = moles / 0.0077 L
0.00077 = moles
Solution B:
18.3 mL / 1,000 = 0.0183 L
Molarity = moles / volume
0.20 M = moles / 0.0183 L
0.00366 = moles
New Solution:
11.7 mL / 1,000 = 0.0117 L
New Volume = 0.0077 L + 0.0183 L + 0.0117 L
New Volume = 0.0377 L
New Moles = 0.00077 moles + 0.00366 moles
New Moles = 0.00443 moles
Molarity = moles / volume
Molarity = 0.0043 moles / 0.0377 L
Molarity = 0.1175 M = 0.12 M
Select the correct answer from each drop-down menu. At chemical equilibrium, the amount of because .
A chemical equilibrium when the amounts of reactants or products no longer change.
Explanation:
Chemical equilibrium is a dynamic process, meaning the rate of formation of products by the forward reaction is equal to the rate at which the products re-form reactants by the reverse reaction.
1. For CCl4, upload a photo including the following: (1) work arriving at total # valence electrons
(2) hand drawn Lewis structure (3) molecular model (4) signature(s) and (5) date.
Work arriving at total valence electrons are 24
The valence electron is an electron in the outer shell associated with an atom, and that can participate in the formation of a chemical bond
For a main-group element, a valence electron can exist only in the outermost electron shell; for a transition metal, a valence electron can also be in an inner shell.
Lewis structures, also known as Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDS), are diagrams that show the bonding between atoms of a molecule, as well as the lone pairs of electrons that may exist in the molecule.
Calculating the work arrival at total valence electrons
We know 1 bond contains
2 valence electrons
Here CCl4 contains 4 bonds that is 8 valence electrons
Therefore ,
Total valence electrons are 32
Now valence electrons remain after bond formation =
32 - 8
=24 valence electrons
A molecular model is a physical model of an atomistic system that represents molecules and their processes
Molecular image and lewis hand drawn structure is as shown below
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Which buffer can be suitable to prepare a solution that needs to be buffered at pH 4? Explain your
choice.
A. Formic acid/Formiate buffer
B. Carbonic acid/Bicarbonate buffer
C. Ammonia/Ammonium buffer
D. Any buffer will work.
E. None of the buffers will be suitable.
34 Which of the following will form a buffer when mixed together? Explain
.
Which buffer can be suitable to prepare a solution that needs to be buffered at pH 4? Explain your
choice.
A. Formic acid/Formiate buffer
B. Carbonic acid/Bicarbonate buffer
C. Ammonia/Ammonium buffer
D. Any buffer will work.
E. None of the buffers will be suitable.
34 Which of the following will form a buffer when mixed together? Explain a weak acid/base and its conjugate base/acid in the form of salt
If it requires 45.8 cal to melt 8.4 g of a substance, what is the heat of
fusion of the substance?
Answer:
5.452 cal/g
Explanation:
45.8 cal / 8.4 g = 5.4523 cal/g
384.72 J is the heat of fusion of the substance.
What is the heat of fusion?It is the change in the value of the enthalpy by providing energy i.e. heat, for a specific quantity of the substance.
Given data:
Heat of fusion =?
Mass of substance = 8.4 g
Unknown:
Amount of energy required to melt the given mass = 45.8 cal
Solution:
To solve this problem, the amount of energy required to melt the substance is given as;
H = m L
m is the mass
L is the heat of fusion
Insert the given parameters and solve;
H = 8.4 g x 45.8 cal = 384.72 J
Hence, 384.72 J is the heat of fusion of the substance.
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How many moles are in a gas with a temperature of 21°C, pressure of 1,351 mmHg and a volume of 2,000 mL
Answer:
.147 moles
Explanation:
PV = n RT choose the correct "R" to be 62.364 L torr /(K-mol)
T needs to be in K (so add 273.15)
1351 torr * 2 L = n * 62.364 * (21 + 273.15 )
solve for n = .147 moles
Calculate the theoretical yield in , grams AlI₃, aluminum iodide, from the complete reaction of 113 grams I₂ according to the following balanced chemical equation: 2Al(s) + 3I₂(s) → 2AlI₃(s)
121 g [tex]AlI_{3}[/tex] aluminum iodide, from the complete reaction of 113 grams I₂ according to the following balanced chemical equation:
2Al(s) + 3I₂(s) → 2[tex]AlI_{3}[/tex]
As per the given balanced equation,
3 moles of [tex]I_{2}[/tex] are used to give 2 moles of [tex]AlI_{3}[/tex].
Atomic weight of iodine is 127 gm/ mole
So, molecular weight of iodine molecule = 254 gm/ mole
There for , we can say that 1 mole o iodine molecule contain 254 g
So ,Given 113 gm iodine contains how many moles?
Moles of iodine = 113/254 = 0.44 moles
from the equation we can say that 3 moles of iodine used to give 2 moles of aluminum iodide.
So, 0.44 moles of iodine gives how many moles of aluminum iodide ?
Moles of aluminum iodide = 0.44 × 2 ÷ 3
= 0.2965 moles
Molecular weight of one mole of aluminum iodide = atomic weight of Al + 3( atomic weight of iodine )
= 408 gm
∴ 1 mole of aluminum iodide = 408 gm
so, 0.2965 moles of aluminum iodide = ?
= 0.2964 × 408
= 121 gm Aluminum iodide formed.
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explain hyaluronic acid
Answer:
Explanation:Hyaluronic acid is a natural substance found in the fluids in the eyes and joints. It acts as a cushion and lubricant in the joints and other tissues.
Different forms of hyaluronic acid are used for cosmetic purposes. Hyaluronic acid might also affect the way the body responds to injury and help to decrease swelling.
Hyaluronic acid injections are US FDA-approved for several conditions, including cataracts, osteoarthritis, and as an injectable gel filler (Juvedérm) for facial wrinkles. People also commonly take hyaluronic acid by mouth and apply it to the skin for UTIs, acid reflux, dry eyes, wound healing, aging skin, and many other conditions, but there is no good scientific evidence to support most of these other uses.
How does it work ?
Uses & Effectiveness ?
Likely Effective for
Cataracts. Injecting hyaluronic acid into the eye is effective when used during cataract surgery by an eye surgeon.
Swelling (inflammation) and sores inside the mouth (oral mucositis). Applying an FDA-approved hyaluronic acid gel is effective for treating mouth sores. It's not clear if other products help.
Answer:
Explanation:
Hyaluronic acid is a natural substance found in the fluids in the eyes and joints. It acts as a cushion and lubricant in the joints and other tissues. Different forms of hyaluronic acid are used for cosmetic purposes. Hyaluronic acid might also affect the way the body responds to injury and help to decrease swelling.
(❛◡❛✿)!
elemental phosphorus occurs as tetratomic molecules, p4. What mass in grams of chlorine gas is need to react completely with 455g of phosphorus to form phosphorus pentachloride?
P₄ + 10Cl₂ → 4PCl₅
mol P₄ = 455 : 123.895 g/mol = 3.672
mol Cl₂ = 10 x 3.672 = 36.72
mass Cl₂ = 36.72 x 71 g/mol = 2607.12 g
