Answer:
6.38×10²¹ molecules
Explanation:
Formula for molybdenum chloride is:
Mo₂Cl₁₀
Molar mass is : (Molar mass for Mo) . 2 + (Molar mass for Cl) . 10
95.94 . 2 + 35.45 . 10 = 546.38 g/mol
We determine moles that are contained in 5.790 g of Mo₂Cl₁₀
5.790 g . 1 mol /546.38 g = 0.0106 moles
We count the molecules: 0.0106 mol . 6.02×10²³ molecules / mol =
6.38×10²¹ molecules
Remember that 6.02×10²³ is also called Avogadro's number (NA) which is the number of particles of anything, that are contained in 1 mol.
What makes radioisotopes useful for dating objects?
O A. They have unique emission spectra.
O B. They decay at a predictable rate.
C. Their decay products are easy to detect.
O D. They all have extremely long half-lives.
Answer:A
Explanation:
Option D. They all have extremely long half-lives makes radioisotopes useful for dating objects.
What are radioisotopes?Radioisotopes exist as radioactive isotopes of an element. They can also be described as atoms that include an unstable combination of neutrons and protons, or surplus energy in their nucleus.
A radionuclide exists as a nuclide that contains excess nuclear energy, causing it unstable. This excess energy can be utilized in one of three methods: emitted from the nucleus as gamma radiation; assigned to one of its electrons to terminate it as a conversion electron; or utilized to create and emit a unique particle from the nucleus.
Radioactive isotopes of radium, thorium, and uranium, for example, exist found naturally in rocks and soil. Uranium and thorium also happen in trace amounts in water. Radon, induced by the radioactive decay of radium, stands present in the air.
Hence, Option D. They all have extremely long half-lives makes radioisotopes useful for dating objects.
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What is the delta H when 72.0 grams H2O condenses at 100.00C?
Here are some constants that you MAY need.
specific heats heat of fusion heat of vaporization
H2O(s) = 2.1 J/g0C 6.01 kJ/mole 40.7 kJ/mole
H2O(L) = 4.18 J/g0C
H2O(g) = 1.7 J/g0C
2930 kJ
163 kJ
-163 kJ
-2930 kJ
Answer: The value of [tex]\Delta H[/tex] is -163 kJZ
Explanation:
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
We are given:
Given mass of water = 72.0 g
Molar mass of water = 18 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of water}=\frac{72.0g}{18g/mol}\\\\\text{Moles of water}=4mol[/tex]
Calculating the heat released for the condensation process:
[tex]\Delta H=n\times \Delta H_{(vap)}[/tex] ......(2)
where,
[tex]\Delta H[/tex] = amount of heat released
n = number of moles of water = 4 moles
[tex]\Delta H_{(vap)}[/tex] = specific heat of vaporization = -40.7 kJ/mol
Negative sign represents the amount of heat released.
Putting values in equation 2:
[tex]\Delta H=4mol\times (-40.7kJ/mol)=-163kJ[/tex]
Hence, the value of [tex]\Delta H[/tex] is -163 kJ
Joelle is a manager at a construction company, and she is interested in the chemistry behind the materials they use. She has begun studying the materials used to fill walls. She knows that to keep the temperature inside a room steady the material must be a thermal insulator, and she predicts that materials should not be acidic or else they would dissolve too easily in water.
Which of these is a molecular ingredient that could be used in a wall-filling material ?
C27H36N2O10
Na6Ba6
NeNa
HCl
Answer:
a
Explanation:
A molecular ingredient that could be used in a wall-filling material is C₂₇H₃₆N₂O₁₀, is not a good thermal insulator, hence option A is correct.
The big molecule C₂₇H₃₆N₂O₁₀ is a poor thermal insulator. Since NeNa is a relatively reactive chemical, it would probably dissolve in water far too quickly. The acidic molecule HCl would dissolve far too quickly in water.
Not a good thermal insulator is C₂₇H₃₆N₂O₁₀. It is a big molecule composed of a lot of hydrogen atoms. Since hydrogen atoms are excellent heat conductors, they would be ineffective in stopping heat from passing through a material used to fill a wall.
Thus, the option (A) C₂₇H₃₆N₂O₁₀ is correct.
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Which equation represents the correct net ionic equation for the reaction between Ca(OH)2 and H2SO4?
Upper H superscript plus, plus upper O upper H superscript minus right arrow upper H subscript 2 upper O.
2 upper H superscript plus, plus 2 upper O upper H superscript minus right arrow upper H subscript 2 upper O.
Upper C a superscript 2 plus, plus 2 upper O upper H superscript minus, plus upper S upper O subscript 4 superscript 2 minus right arrow upper C a superscript 2 plus, plus upper S upper O subscript 4 superscript 2 minus, plus 2 upper H subscript 2 upper O.
Upper C a (upper O upper H) subscript 2 plus upper H subscript 2 upper S upper O subscript 4 right arrow upper C a upper S upper O subscript 4 plus 2 upper H subscript 2 upper O.
Answer: The correct net ionic equation for the reaction is [tex]2H^{+}(aq)+2OH^{-}(aq)\rightarrow 2H_2O(l)[/tex]
Explanation:
Net ionic equation is defined as the equations in which spectator ions are not included.
Spectator ions are the ones that are present equally on the reactant and product sides. They do not participate in the reaction.
The balanced molecular equation is:
[tex]Ca(OH)_2(aq)+H_2SO_4(aq)\rightarrow CaSO_4(aq)+2H_2O(l)[/tex]
The complete ionic equation follows:
[tex]Ca^{2+}(aq)+2OH^-(aq)+2H^+(aq)+SO_4^{2-}(aq)\rightarrow 2Ca^{2+}(aq)+SO_4^{2-}(aq)+H_2O(l)[/tex]
As calcium and sulfate ions are present on both sides of the reaction. Thus, they are considered spectator ions.
The net ionic equation follows:
[tex]2H^{+}(aq)+2OH^{-}(aq)\rightarrow 2H_2O(l)[/tex]
Hence, the correct net ionic equation for the reaction is [tex]2H^{+}(aq)+2OH^{-}(aq)\rightarrow 2H_2O(l)[/tex]
Answer:
B. no reaction
Explanation:
Briefly explain why adding insulation to an attic helps reduce heating costs.
Answer:
Insulation reduces the exchange of heat through a surface such as a wall, attic, duct or roof. In a well-insulated home, less warm air escapes from the house during the winter, and less cool air escapes during the summer, reducing the amount of energy needed for heating and cooling
A carbon atom that is surrounded by four hydrogen atoms has a _____ molecular geometry. This geometry results from the arrangement of the _____ hybrid orbitals around the carbon atom. They are formed when the s-orbital and ______ -orbitals mix, or hybridize.
Answer:
Tetrahedral, sp3, p
Explanation:
C has 4 bonds and hence its tetrahedral shape with 109.5 degrees. since there are 4 bonds, it is sp3
Answer:
A carbon atom that is surrounded by four hydrogen atoms has a
✔ tetrahedral
molecular geometry.
This geometry results from the arrangement of the
✔ four sp3
hybrid orbitals around the carbon atom.
They are formed when the s-orbital and
✔ three p
-orbitals mix, or hybridize.
Explanation:
Use mathematics to prove that the 5.50 grams of salicylic acid (C7H6O3) used in this experiment is equal to 0.04 mol.
Answer:
Please find the answer to the question below
Explanation:
In chemistry, the following mathematical formula is used to calculate the number of moles contained by a substance:
mole = mass of substance (g)/molar mass of substance (g/mol)
Molar mass of salicylic acid (C7H6O3) = 12(7) + 1(6) + 16(3)
= 84 + 6 + 48
= 138g/mol
Mass = 5.50grams
mole = 5.5/138
mole = 0.039
Approximately, the number of moles of 5.5grams of salicylic acid is 0.04moles. This is in accordance with the mole value (0.04) given in this question.
Which substance would you expect to dissolve most rapidly in 100 mL water?
A
0.4 g granulated sugar
B
0.2 g powdered sugar
C
0.4 g powdered sugar
D
0.2 g sugar cube
Answer:
b because it is just 0.2 g and powdered sugar has more contact surface than granulated sugar or sugar cube
The solubility can be given as the amount of solute that can be dissolved in the 100 ml of the solution. The most rapidly dissolved sugar in water is 0.2 gram powdered sugar.
What is a contact surface?The contact surface can be given as the area of the compound that is in direct contact with the solution.
The solubility of the compound is found more in the solute with increased surface area.
The surface area of powdered sugar will be maximum, as more granules of the sugar will be in contact with the water than the cube or the granulated sugar.
Thus, the most rapid dissolution in water is found with 0.2 grams of powdered sugar. Thus, option B is correct.
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How much heat is required to raise the temperature of 16.0 grams H2O from 5.000C to 75.00C? Below is a list of constants.
specific heat for H2O(s) = 2.1 J/g0C
specific heat for H2O(L) = 4.18 J/g0C
specific heat for H2O(g) = 1.7 J/g0C
\bigtriangleup H△Hvap = 40.7 kJ/mol
\bigtriangleup H△Hfus = 6.01 kJ/mol
5.34 J
260 J
4680 J
2350 J
Answer:
The amount of heat required is 4681.6 J.
Explanation:
mass, m = 16 g = 0.016 kg
initial temperature, T = 5 C
final temperature, T' = 75 C
specific heat, c = 4.18 J/g C
The amount of heat required is
H = m c (T'- T)
H = 16 x 4.18 x (75 - 5)
H = 4681.6 J
Which of these is not a mixture?
A) Salt
B) Cooking oil
C) Tea leaves
D) Milk
ty
Answer:
the answer is salt because it has a uniform and definite composition
Explanation:
What is the pH of a solution?
O A. A measure of the strength of the acid
B. A measure of the buffering ability of the solution
O c. A measure of the hydrogen gas concentration
O D. A measure of the acidity of the solution
Answer:
D. A measure of the acidity of the solution
Explanation:
pH is a measure of how acidic or basic a solution is, and is measured on a scale from 0-14, where 7 is neutral, anything less than 7 is acidic, and anything more than 7 is basic.
Michael is studying the factors that affect corrosion of metals. He wants to test the effect that different concentrations of an acid will have on the corrosion of a metal. As he sets up and completes his experiment, which of the following experimental designs would be most likely to help him answer his question? A. Allow several metal samples to soak in different amounts of acid of a single concentration and then measure the amount of corrosion on each. B. Prepare solutions of different acid concentrations, measure 50 milliliters of each into different beakers, and place metal samples of different types but of the same mass into the beakers. C. After allowing several small metal sheets to be exposed to different acid concentrations, measure the surface area of each that is corroded. D. After allowing a small metal sheet to be exposed to one acid concentration, place it in different acid concentrations, then measure the surface area that is corroded.
Answer:
B. Prepare solutions of different acid concentrations, measure 50 milliliters of each into different beakers, and place metal samples of different types but of the same mass into the beakers.
Explanation:
Since Michael is studying the factors that affect corrosion of metals, and wants to test the effect that different concentrations of an acid will have on the corrosion of a metal, using different acid concentrations of the same volume on different metal samples of the same size would give a much better than all the other options because, a standard volume of acid is used and also a standard mass of metal is used. So, the effect can be measured quantitatively since we have the same quantity of sample.
So, option B is the answer
Which of these is true about a pH meter?
It is inexpensive to use.
It measures pH indirectly.
It does not require calibration.
It can be used in any acid-base titration.
Answer:
That is, a pH meter is useful in detecting or knowing the acidity (due to ions) or alkalinity (due to ions) of a solution. Thus, we can conclude that out of the given options it is true about a pH meter that it can be used in any acid-base titration
Answer: D. It can be used in any acid-base titration.
Explanation:
show using dots to illustrate high population density and low population density in the boxes provided in answer to guide questions
Answer:
Just add a plenty of dots in the first one and very few dots in the second one
An area with high population density will have many dots while areas will low population density will have few dots when using dots to illustrate population density.
What is population density?Population density is the ratio of the total number of organisms found in a given area to the total of the area of that place or habitat.
Population density = total number of organisms/total areaAn area with high population density indicates that more organised ate found per unit area than an area with low population density.
Therefore, using dots to illustrate population density, an area with high population density will have plenty dots while areas will low population density will have few dots scattered over.
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Matter takes up _____.
(a) Space and temperature
(b) Space and heat
(c) Space and mass
(d) Heat and temperature
Please help I’ll give brainliest
Answer:
N2, O2 and Br2
Explanation:
N2, O2 and Br2 are formed of two atoms, so they are diatomic
This is a list of the seven diatomic elements. The seven diatomic elements are:
Hydrogen (H2)
Nitrogen (N2)
Oxygen (O2)
Fluorine (F2)
Chlorine (Cl2)
Iodine (I2)
Bromine (Br2)
Por qué razón se fomenta la inmigración Europea?
Hola aquí va la respuesta!
Se fomentó la inmigración europea porque la economía no era buena y vinieron a Paraguay para mejorar su situación.
Hola aquí va la respuesta!
Se fomentó la inmigración europea porque la economía no era buena y vinieron a Paraguay para mejorar su situación.
Which sequence of steps describes the life cycle of a lake?
A. Runoff fills a depression - sediments build up - water becomes
increasingly shallow
B. Runoff fills a depression - sediments are eroded - water becomes deeper
C. Runoff fills a depression - sediments build up
- water rises continuously
D. Runoff fills a depression - sediments are eroded - water spreads over a wider area
Answer:
The actual sequence of steps which describe the life cycle of a lake is given below:
C. Runoff fills a depression - sediments build up
- water rises continuously
Explanation:
This is because, the water which builds up as a result of the runoff water accumulating on the depression helps towards building up. When it must have accumulated greatly, it ends up forming a lake.
copper +sulfur + oxygen =
Help me with this this is something i dont know and its not on here please help meeeeeee
Answer:
it would be option A
Explanation:
This is becuase if you look at the chart you can see tyhat the group of rats that got feed to vitamans did gain more wati then the ones on the normal diet.
A + 2 B + 4 C → products is known to be second order in A, first order in B and independent of the concentration of C. What is the value of the rate constant for this reaction if its rate is 0.783 M · s−1 when [A] = 5.00 M, [B] = 7.00 M, and [C] = 3.00 M? −2 −1 Answerinunitsof M ·s .
Answer:
4.47 × 10⁻³ M⁻² s⁻¹
Explanation:
Let's consider the following generic equation.
A + 2 B + 4 C → products
This reaction is known to be second order in A, first order in B and independent of the concentration of C (zero order in C). The rate law is:
rate = k × [A]² × [B] × [C]⁰
rate = k × [A]² × [B]
where k is the rate constant
When the rate is 0.783 M/s, [A] = 5.00 M, [B] = 7.00 M, and [C] = 3.00 M, the rate constant is:
k = rate / [A]² × [B]
k = 0.783 M/s / (5.00)² × (7.00) = 4.47 × 10⁻³ M⁻² s⁻¹
If the pH = 6.5, what is the [H+]? *
3.16 x 10-7
3.16 x 10-6
O
3.16 x 10-5
Answer:
Key Concepts
The hydrogen ion concentration in a solution, [H+], in mol L-1, can be calculated if the pH of the solution is known.
pH is defined as the negative logarithm (to base 10) of the hydrogen ion concentration in mol L-1 pH = -log10[H+] ...
[H+] in mol L-1 can be calculated using the equation (formula): [H+] = 10-pH
More items...
Explanation:
Answer:
[tex]pH = - log[H {}^{ + } ] \\ 6.5 = - log[H {}^{ + } ] \\ [H {}^{ + } ] = {10}^{ - 6.5} \\ [H {}^{ + } ] = 3.16 \times {10}^{ - 7} \: mol {dm}^{ - 3} [/tex]
Which of the following best describes an electron transition?
A. An electron gains or loses energy and moves between continuous
energy levels.
B. An electron gains or loses charge and changes into a proton or a
neutron.
C. An electron gains or loses energy and moves between quantized
energy levels.
D. An atom gains or loses an electron and becomes an ion.
Answer:
A. An electron gains or loses energy and moves between continuous
energy levels.
an engineer chooses to use bamboo as a building material because it grows quickly and needs little space to grow. This is an example of?
Answer:
A) This is an example of Green Design
Explanation:
Si se hace reaccionar CH3CH3 (etano) con cloro, en presencia de luz ultravioleta, los productos obtenidos en este paso son
Answer:
La reacción de etano, CH₃CH₃ y cloro, Cl₂ en presencia de luz solar se conoce como reacción de halogenación.
Los radicales de cloro se forman cuando el cloro se expone a la luz solar a continuación;
Cl₂ → 2Cl *
Se forma un radical etano cuando el etano, C₂H₆ reacciona con un radical libre de cloro, Cl *, como sigue;
C₂H₆ + Cl → C₂H₅ * + HCl
Se forma un producto halogenado cuando un radical libre de etano reacciona con una molécula de cloro como sigue;
C₂H₅ * + Cl₂ → C₂H₅Cl + Cl *
Un producto halogenado puede reaccionar además con un radical libre para producir como sigue;
C₂H₅Cl + Cl * → C₂H₅Cl₂
Explanation:
Elias read a book about California earthquakes. He then wrote a three-
paragraph report about the book. Which of the following active reading
strategies did Elias use?
A. Making mental images
B. Drawing inferences
C. Summarizing
D. Making predictions
What happens when an unstable nucleus undergoes radioactive decay?
A. Electrons change energy levels to balance the nucleus.
B. Energy is absorbed by the nucleus to make it more stable.
O C. Particles or electromagnetic radiation are emitted.
D. The nucleus increases in mass through radioactive decay.
how does evelyn hear music?
Which list BEST identifies how the arrows should be arranged around the paper leaf in the model to represent the movement of matter and flow of energy during photosynthesis? A. Point into Leaf: sugars, oxygen (02), Point away from leaf: carbon dioxide(CO2), water(H2O) B. Point into Leaf: sugars, sunlight, Point away from leaf: carbon dioxide(CO2), oxygen (02), water(H2O) C. Point into Leaf: water(H2O), sunlight, Point away from leaf: carbon dioxide(CO2), sugars, oxygen (02) D. Point into Leaf: water(H2O), carbon dioxide(CO2) sunlight, Point away from leaf: sugars, oxygen (02
Answer:
D. Point into Leaf: water(H₂O), carbon dioxide (CO₂) sunlight, Point away from leaf: Sugars, oxygen (O₂)
Explanation:
Photosynthesis is the process used in the production of chemical energy in the form of energy containing organic compounds and oxygen from atmospheric carbon dioxide and liquid water enabled with the energy captured from light (mainly Sunlight) by the chlorophyll in green plants and other organisms
The basic chemical reaction involved in a photosynthesis reaction is presented as follows;
[tex]{}[/tex] Sunlight
[tex]{}[/tex] ↓
[tex]{}[/tex] CO₂ + H₂O (l) → C₆H₁₂O₆ + O₂
Carbon dioxide [tex]{}[/tex] Water Glucose Oxygen
