Answer:
The wood sample has an age of approximately 22800 years.
Explanation:
The Becquerel ([tex]Bq[/tex]) is a SI unit which describes radioactive activity related to decay of radioactive isotopes, which is equivalent to [tex]\frac{1}{s}[/tex]. The decay of radioactive isotope is described by the following ordinary differential equation:
[tex]\frac{dN}{dt} = -\frac{N}{\tau}[/tex] (Eq. 1)
Where:
[tex]\frac{dN}{dt}[/tex] - Disintegration rate, measured in [tex]\frac{1}{s}[/tex].
[tex]N[/tex] - Amount of remaining radioactive nuclei, dimensionless.
[tex]\tau[/tex] - Time constant, measured in seconds.
By integration the solution of this differential equation is obtained:
[tex]\int {\frac{dN}{N} } = -\frac{t}{\tau}\int dt[/tex]
[tex]\ln N = -\frac{t}{\tau} + C[/tex]
[tex]N(t) = N_{o}\cdot e^{-\frac{t}{\tau} }[/tex] (Eq. 2)
Let [tex]N_{1}[/tex] and [tex]N_{2}[/tex] different disintegration rates for Carbon-14 samples, so that:
[tex]N_{1} = N_{o} \cdot e^{-\frac{t_{1}}{\tau} }[/tex] (Eq. 3)
[tex]N_{2} = N_{o}\cdot e^{-\frac{t_{2}}{\tau} }[/tex] (Eq. 4)
If we divide (Eq. 4) by (Eq. 3), then:
[tex]\frac{N_{2}}{N_{1}} = \frac{N_{o}\cdot e^{-\frac{t_{2}}{\tau} }}{N_{o}\cdot e^{-\frac{t_{1}}{\tau} }}[/tex]
[tex]\frac{N_{2}}{N_{1}} = e^{-\frac{1}{\tau}\cdot (t_{2}-t_{1}) }[/tex] (Eq. 5)
If [tex]\Delta t = t_{2}-t_{1}[/tex], we proceed to clear that variable:
[tex]\ln \frac{N_{2}}{N_{1}} = -\frac{1}{\tau}\cdot \Delta t[/tex]
[tex]\Delta t = -\tau\cdot \ln \frac{N_{2}}{N_{1}}[/tex] (Eq. 6)
Time constant is also a function of half-life ([tex]t_{1/2}[/tex]), measured in seconds:
[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex]
If [tex]t_{1/2} = 1.798\times 10^{11}\,s[/tex], [tex]N_{1} = 14\,\frac{1}{s}[/tex] and [tex]N_{2} = 0.875\,\frac{1}{s}[/tex], the age of the wood sample is:
[tex]\tau = \frac{1.798\times 10^{11}\,s}{\ln 2}[/tex]
[tex]\tau = 2.594\times 10^{11}\,s[/tex]
[tex]\Delta t = -(2.594\times 10^{11}\,s)\cdot \ln \left(\frac{0.875\,\frac{1}{s} }{14\,\frac{1}{s} } \right)[/tex]
[tex]\Delta t \approx 7.192\times 10^{11}\,s[/tex]
[tex]\Delta t \approx 22805.682\,yr[/tex]
The wood sample has an age of approximately 22800 years.
What type of energy is the sun of an objects potential and kinetic energy
All of the energy from the Sun that reaches the Earth arrives as solar radiation, part of a large collection of energy called the electromagnetic radiation spectrum. Solar radiation includes visible light, ultraviolet light, infrared, radio waves, X-rays, and gamma rays. Radiation is one way to transfer heat.
12. In the modern periodic table, which of the following describes the elements with similar
properties?
A. They have similar atomic masses.
B. They are located in the same group.
C. They are located in the same period.
D. They have the same number of protons.
Which of the following BEST describes the main function of carbohydrates?
a
Speeding up chemical reactions
b
Fuel
c
Instructions for making proteins
d
Energy storage
The atmospheric conditions that exist for a long period of time in a given area are called what?
Answer:
Climate
Explanation:
Entropy is a measure of
1.
accuracy
2.
precision
3.
the disorder of a system
4.
the attraction of a nucleus for an electron
Answer:
The answer is actually 3. The disorder of a system.
Enter your answer in the provided box. A sample of an unknown gas effuses in 11.1 min. An equal volume of H2 in the same apparatus under the same conditions effuses in 2.42 min. What is the molar mass of the unknown gas
Answer: The molar mass of the unknown gas is 9 g/mol
Explanation:
From Graham's law of effusion rates, the rate of effusion of a gas is inversely proportional to the square root of its molar mass.
[tex]\frac{rate_1}{rate_2}=\sqrt{\frac{M_2}{M_1}} [/tex]
[tex]rate=\frac{volume}{time} [/tex]
Rate is volume effused per unit time. Since, the volumes are same, the formula could be written as:
[tex]\frac{t_B}{t_A}=\sqrt{\frac{M_B}{M_A}}[/tex]
Putting the values in the formula:
[tex]\frac{2.42min}{11.1min}=\sqrt{\frac{M_{H_2}}{M_A}} [/tex]
[tex]\frac{2.42min}{11.1min}=\sqrt{\frac{2}{M_A}} [/tex]
Squaring both sides:
[tex]\frac{2}{M_A}=0.218[/tex]
[tex]M_A=9g/mol[/tex]
The molar mass of the unknown gas is 9 g/mol
If you collect 5.74 mL of O 2 at 298 K and 1.00 atm over 60.0 seconds from a reaction solution of 5.08 mL, what is the initial rate of the reaction
Answer:
7.71 × 10⁻⁴ M/s
Explanation:
The initial rate of the reaction can be expressed by using the formula:
[tex]\dfrac{\Delta [O_2]}{\Delta t}[/tex]
where the number of moles of O₂ = [tex]\dfrac{PV}{RT}[/tex]
where;
Pressue P = 1.00 atm
Volume V =5.74mL = (5.74 /1000) L
Rate R = 0.082 L atm/mol.K
Temperature = 298 K
[tex]= \dfrac{1.00 \ atm \times \dfrac{5.74 }{1000}L}{0.082 \ L \ atm/mol.K \times 298 K}[/tex]
= 2.35 × 10⁻⁴ mol
Δ[O₂] = [tex]\dfrac{moles \ produced - initial \ mole}{\dfrac{5.08 }{1000}L }[/tex]
Δ[O₂] = [tex]\dfrac{2.35 \times 10^{-4} M - 0 M}{\dfrac{5.08 }{1000}}[/tex]
Δ[O₂] = 0.04626 M
The initial rate = [tex]\dfrac{\Delta [O_2]}{\Delta t}[/tex]
= [tex]\dfrac{0.04626}{60}[/tex]
= 7.71 × 10⁻⁴ M/s
Many scientists have contributed to the atomic theory. In 1803 John Dalton gave new insight to this theory. Which desciption of an atom fits our most
current understanding?
Fyry nyyden atom is the same as every hydrogen atom
Both olives and the leaves of olive trees contain alkanes with long carbon chains. A predominant alkane in olives has 27 carbons, whereas a major alkane component in olive leaves has 31 carbons. What is the molecular formula of each of these alkanes?
Answer:
Explanation:
Alkanes are saturated hydrocarbons (i.e they do not have any double/triple bond within there carbon chain). They have the general formula CₙH₂ₙ₊₂ where n is the number of carbons and starts with 1.
Since the predominant alkane in the olive has 27 carbons, it's molecular formula will be C₂₇H₍₂ₓ₂₇₎₊₂ ⇒ C₂₇H₅₆
The major alkane component in the olive leaves has 31 carbons, hence it's molecular formula will be C₃₁H₍₃₁ₓ₂₎₊₂ ⇒ C₃₁H₆₄
Which statement best compares the amount of fossil fuels formed each year to the amount used each year?
Answer: The amount of fossil fuels formed is approximately the same as the amount used.
Explanation:
The amount of fossil fuels formed is approximately the same as the amount used. The amount of fossil fuels formed is much less than the amount used. The amount of fossil fuels formed is greater than the amount used.
The amount of fossil fuels formed is much less than the amount used. The correct option is C.
What is fossil fuel?Fossil fuels are deduced from the putrefaction of both animals and plants. These fuels, which can be discovered in the Earth's crust as well as encapsulate carbon and hydrogen, can be burned for energy.
Fossil fuels include coal, oil, and natural gas. The amount of fossil fuels produced is significantly less than the amount consumed.
The compounds that comprised up plankton as well as plants transform into fossil fuels after millions of years underground. Plants decompose into coal while plankton decomposes into natural gas and oil.
These resources are now extracted by humans through coal mining and the drilling of oil and gas wells on land and offshore.
Warming would certainly slow if we stopped using fossil fuels today, but removing greenhouse gases from the atmosphere will have to happen eventually.
Thus, the correct option is C.
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Your question seems incomplete, the missing options are:
The amount of fossil fuels formed is exactly the same as the amount used.
The amount of fossil fuels formed is approximately the same as the amount used.
The amount of fossil fuels formed is much less than the amount used.
The amount of fossil fuels formed is greater than the amount used.
In the reaction between lead(II) nitrate and sodium chloride, what, if any, are the spectator ions
Answer:
Explanation:
Spectator ions are ions in a solution/reaction that do not take part in a chemical reaction (hence are called "spectator" ions). They can be identified when they are found both in the reactant and product sides.
The reaction between lead(II) nitrate, Pb(NO₃)₂ and sodium chloride, NaCl is illustrated below
Pb(NO₃)₂ + 2NaCl ⇒ PbCl₂ + 2NaNO₃
According to solubility rules, all the compounds above (with the exception of PbCl₂) are all soluble and would dissociate when involved in a reaction.
Hence, the ionic equation based on the description above will be
Pb²⁺ + 2NO₃⁻ + 2Na⁺ + 2Cl⁻ ⇒ PbCl₂ + 2Na⁺ + 2NO₃⁻
From the above ionic equation, it can be noted that both 2NO₃⁻ and 2Na⁺ are found on both the reactant and product side and are hence the spectator ions.
Copying is not allowed. You must show all work in order to receive credit. Naturally occurring silver has two isotopes. Isotope A has a relative mass of 106.9051 and an abundance of 51.82%. Isotope B has a relative mass of 108.9047. Calculate the atomic mass of silver from these data.
Answer: The atomic mass of silver is 107.8
Explanation:
Average atomic mass is the average mass of all the isotopes present depending on the relative abundance of each isotope.
Mass of isotope A = 106.9051
% abundance of isotope 1 = 51.82% = [tex]\frac{51.82}{100}[/tex]
Mass of isotope B = 108.9047
% abundance of isotope 2 = (100-51.82)% = [tex]\frac{48.18}{100}[/tex]
Formula used for average atomic mass of an element :
[tex]A=\sum[(106.9051)\times \frac{51.82}{100})+(108.9047)\times \frac{48.18}{100}]][/tex]
[tex]A=107.8[/tex]
Therefore, the average atomic mass of silver is 107.8
Writing key words in the margin is part of which note-taking procedure?
Select one:
a. record
b. review
c. reduce
d. recite
Calcium's valence shell holds two electrons. Chlorine's valence shell holds seven electrons. Which represents the ions that are bonded in
calcium chloride?
A. Ca^2+ + 2Cl-
B. Ca^2- + 2CI+
C. 2Ca+ + 2C1-
D. Ca\/2+ + Cl\/2-
if u trust urself do it! (not sponsored by nike)
Which is one factor that contributes to the formation of polar, temperate, and tropical zones?
the angle of the Sun’s rays
the direction of seasonal winds
the presence of prevailing winds
the movement of wind near a mountain
Answer: A) The angle of the Sun's rays!
Answer:
A) The angle of the Sun's rays!
Explanation:
A rock dropped in a graduated cylinder raises the level of water from 20 mL to 35 mL. The rock has a mass of 45 g. What is the density of the rock?
Which of the following objects would have the smallest wavelength at the same velocity?
Baseball
Electron
Planet Earth
Proton
Answer: Planet Earth
Explanation: Wavelength (λ) is equal to h/mυ , where m = the mass of your object and υ = the frequency. Since Earth has the largest mass of the options, we can conclude that Earth will have the smallest wavelengths out of the rest.
The wavelength of matter-waves is given by the De Broglie formula. The larger the object, the smaller the observed wavelength hence the object having the smallest wavelength is Planet Earth.
De Broglie established the relationship between the momentum and the observed wavelength of an object. This proposition came to be known as wave-particle duality.
The wavelength of matter waves is given by;
λ = h/mv
Where;
λ = wavelength
m = mass of object
v = velocity of the object
If all the objects have the same velocity, the magnitude of the wavelength now depends on the mass of the object.
The object having the largest mass among the options is planet earth (5.972 × 10^24 kg).
Hence planet earth has the smallest wavelength among the options listed.
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When methylcyclobutane is treated with chlorine gas and heated, the total number of monochlorinated products, including stereoisomers, is
Answer:
5
Explanation:
The image attached shows the different monochlorination products obtained when chlorine gas is heated with methylcyclobutane.
We must keep in mind that the reaction occurs by free radical mechanism as shown in the image attached. The proportion in which the products are formed depends on the stability of the free radical intermediate leading to that particular product.
Image credit: askiitians
Describe the relationship of the Earth’s lithosphere to the asthenosphere.
The asthenosphere is composed of rigid plates that “float” on top of the lithosphere.
The lithosphere is composed of rigid plates that “float” on top of the asthenosphere.
The lithosphere is a solid wall around the asthenosphere, and they move as one unit.
The asthenosphere is found in the Earth’s core and is protected by the lithosphere.
Answer:
The lithosphere is the brittle crust and uppermost mantle. The asthenosphere is a solid but it can flow, like toothpaste. The lithosphere rests on the asthenosphere
Explanation:
Answer:
pretty sure its B
Explanation:
might not be tho but pretty sure it is
If 550 grams of KClO3 breaks down and produces 175 grams of KCl, how many grams of O2 are produced?
Answer:
215.51 g of O2.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is illustrated below:
2KClO3 —> 2KCl + 3O2
Next, we shall determine the mass of KClO3 that decomposed and the mass of O2 produced from the balanced equation. This is illustrated below:
Molar mass of KClO3 = 39 + 35.5 + (16×3)
= 39 + 35.5 + 48
= 122.5 g/mol
Mass of KClO3 from the balanced equation = 2 × 122.5 = 245 g
Molar mass of O2 = 16 × 2 = 32 g/mol
Mass of O2 from the balanced equation = 3 × 32 = 96 g
From the balanced equation above,
245 g of KClO3 decomposed to produce 96 g of O2.
Finally, we shall determine the mass of O2 produced by the decomposition of 550 g of KClO3. This can be obtained as follow:
From the balanced equation above,
245 g of KClO3 decomposed to produce 96 g of O2.
Therefore, 550 g of KClO3 will decompose to produce =
(550 × 96)/245 = 215.51 g of O2.
Therefore, 215.51 g of O2 were obtained from the reaction.
3. Explain the gravitational force earth has with one other object in the solar
system.
I
Answer: It's gravity keeps the Moon orbiting around the Earth.
Explanation:
Using Gizmo ,describe the main use for each fuel Coal: Petroleum: In each case, what is the end product of burning the fossil fuel,and where does it go? Help is for today
Answer:
See explanation
Explanation:
Coal is primarily used for electricity generation. The burning of coal leads to emission of gases such as oxides of carbon, oxides of sulphur, oxides of nitrogen and water vapour. All these go straight into the atmosphere.
Petroleum is primarily used as transportation fuels. The burning of petroleum oils mostly leads to the emission of oxides of carbon and sulphur together with water vapour into the atmosphere.
The rock has a mass of 7.9g and a volume of 3.0 cm3. What is the density of the rock?
Answer:
The answer is 2.63 g/cm³Explanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\ [/tex]
From the question we have
[tex]density = \frac{7.9}{3} \\ = 2.633333...[/tex]
We have the final answer as
2.63 g/cm³Hope this helps you
Peroxyacylnitrate (PAN) is one of the components
of smog. It is a compound of C, H, N, and O.
Determine the percent composition of oxygen and
the empirical formula from the following percent
composition by mass: 19.8 percent C,
2.50 percent
H, 11.6 percent N. What is its molecular formula
given that its molar mass is about 120 g?
C – 19,9%, H – 2,2%, N – 11,6%, O – x%
[tex]M=120\frac{g}{mol}[/tex]
1 percentage
The entire molecule is 100% and all the components of the compound add up to 100%.
100% - 19,9% - 2,5% - 11,6% = 66,1%
The compound contains 66,1% oxygen.
2 molar masses
[tex]M_{C}=12,01\frac{g}{mol}[/tex]
[tex]M_{H}=1,008\frac{g}{mol}[/tex]
[tex]M_{O}=15,999\frac{g}{mol}[/tex]
[tex]M_{N}=14,007\frac{g}{mol}[/tex]
3 masses
The compound has a molar mass of 120g/mol. So one molecule weighs 120 g. To find out how much the percentage of a component weighs, you have to calculate it using the molar mass.
carbon
19,8% of 120g
[tex]m=120g*0,198\\m=23,76g[/tex]
One molecule contains 23,76g of carbon.
hydrogen
2,5% of 120g
[tex]m=120g*0,025\\m=3g[/tex]
One molecule contains 3g of hydrogen.
oxygen
66,1% of 120g
[tex]m=120g*0,661\\m=79,32g[/tex]
One molecule contains 79,32g of oxygen.
nitrogen
11,6% of 120g
[tex]m=120g*0,0,116\\m=13,92g[/tex]
One molecule contains 13,92g of nitrogen.
4 amount of substance
carbon
[tex]n=\frac{23,76g}{12,01\frac{g}{mol} }\\n=1,98mol[/tex]
The compound contains about 2 moles of carbon.
hydrogen
[tex]n=\frac{3g}{1\frac{g}{mol} }\\n=3mol[/tex]
The compound contains about 3 moles of hydrogen.
oxygen
[tex]n=\frac{79,32g}{15,999\frac{g}{mol} }\\n=4,96mol[/tex]
The compound contains about 5 moles of oxygen.
nitrogen
[tex]n=\frac{13,92g}{14,007\frac{g}{mol} }\\n=0,99mol[/tex]
The compound contains about 1 moles of nitrogen.
5. molecular formula
The formula results from the ratio of the amounts of substance.
[tex]n_{C} :n_{H} :n_{O} :n_{N} =2:3:5:1\\C_{2}H_{3}NO_{5}[/tex]
The molecular formula of the given compound is C₂H₃NO₅, and percent composition of oxygen in it is 66.1%.
How do we calculate mass from % composition?Mass of any composition of any compound will be calculated by using the below formula as:
Mass of component = (% composition)×(mass of compound) / 100
Given mass of compound = 120g/mol
Total composition of compound (100%) = Percent composition of all components
% composition of oxygen = 100 - (19.8 + 2.50 + 11.6) = 66.1%
Moles will be calculated as:
n = W/M, where
W = given mass
M = molar mass
For carbon atom:Mass of Carbon component = (0.198)(120g) = 23.76g
Moles of Carbon atom = 23.76g / 12.01g/mol = 1.98mol = 2 moles
For nitrogen atom:Mass of Nitrogen component = (0.116)(120g) = 13.92g
Moles of Nitrogen atom = 13.92g / 14.007g/mol = 0.99mol = 1 moles
For oxygen atom:Mass of Oxygen component = (0.661)(120g) = 79.32g
Moles of Oxygen atom = 79.32g / 15.99g/mol = 4.96mol = 5 moles
For hydrogen atom:Mass of Hydrogen component = (0.025)(120g) = 3g
Moles of Hydrogen atom = 3g / 1g/mol = 3 moles
So, the molecular formula of the compound on the basis of moles of given entities is C₂H₃NO₅.
Hence required molecular formula is C₂H₃NO₅.
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A gas has a volume of 300 mL and a pressure of 2 atm. What volume will the gas occupy when the pressure is
increased to 7 atm (total)?
Answer:
The answer is 85.71 mLExplanation:
The new volume can be found by using the formula for Boyle's law which is
[tex]P_1V_1 = P_2V_2[/tex]
where
P1 is the initial pressure
P2 is the final pressure
V1 is the initial volume
V2 is the final volume
Since we are finding the new volume
[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]
We have
[tex]V_2 = \frac{300 \times 2}{7} = \frac{600}{7} \\ = 85.714285...[/tex]
We have the final answer as
85.71 mLHope this helps you
Why is energy involved in changes of state?
Answer:
The energy of particles of matter determines the matter's state. Particles of a gas have more energy than particles of a liquid, and particles of a liquid have more energy than particles of a solid. Therefore, in order for matter to change from a solid to a liquid or from a liquid to a gas, particles of matter must absorb energy. In order for matter to change from a gas to a liquid or from a liquid to a solid, particles of matter must lose energy.
The system will lose or gain energy as a result of changing its state, which is why energy will be involved in state changes.
What is energy?
Energy is a quantitative property that would be transferred to a body or even a physical system and is visible in term of heat as well as light during the performance of work.
Whenever a state changes, energy is involved. When matter transitions through one state to another, it either releases or absorbs energy. When matter transforms from such a liquid to a solid, for example, it loses energy. When matter transforms from a solid to a liquid, the opposite occurs.
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which angles are right
Answer:
a right is 90 degrees
Josh heated a certain amount of blue copper sulfate crystals to get 2.1 g of white copper sulfate powder and 1.4 g of water. What is most likely the mass of the blue copper sulfate that he heated and why?
Answer: The mass of blue copper sulfate is 3.5 g
Explanation:
Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total mass on the reactant side must be equal to the total mass on the product side.
The chemical equation for the heating of copper sulfate crystals is:
Let the mass of blue copper sulfate be 'x' grams
We are given:
Mass of copper sulfate powder = 2.1 grams
Mass of water = 1.4 grams
Total mass on reactant side = x
Total mass on product side = (2.1 + 1.4) g
So, by applying law of conservation of mass, we get:
Hence, the mass of blue copper sulfate is 3.5 grams
The use of water in a heat exchanger is taking advantage of water's A. high specific heat. B. significant expansion during boiling. C. solid state when frozen. D. polar molecular nature
Answer:
A. high specific heat.
Explanation:
Specific heat defines the heat or thermal capacity of a substance.
Water has a high specific heat which adds an advantage to a heat exchanger. Due to the high heat or thermal capacity of the water heat exchanger can transfer a huge amount of heat between two or more fluids.
Hence, the correct answer is "A. high specific heat."
Answer:
A. high specific heat.
Explanation:
The reverse of the process of sublimation is called
Answer:
Desublimation
Explanation:
The reverse of deposition is sublimation and hence sometimes deposition is called desublimation.
HOPE THIS HELPS
