The half-life of radon-222 is 4 days, which means that after each 4-day period, the amount of radon-222 in a sample is halved.
After 8 days, only 25 g of the 100 g sample of radon-222 would be remaining. After 8 days, there have been two half-life periods. Therefore, we can find the amount of radon-222 remaining after 8 days using the following formula:
Amount remaining = (Initial amount) x (1/2)^(number of half-life periods)
Initial amount = 100 g
Number of half-life periods = 8 days / 4 days per half-life = 2 half-life periods
Substituting these values into the formula gives:
Amount remaining = 100 g x (1/2)² = 100 g x (1/4) = 25 g
Therefore, after 8 days, only 25 g of the 100 g sample of radon-222 would be remaining.
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ASAP PLEASE!!!3. Reasoning: Explain how the evidence supports your claim. Explain how the
evidence from your data table shows the trends for valence electrons for both
groups and periods on the periodic table. (4 points)
The data table supports the idea that valence electrons affect the chemical characteristics of elements and may be used to forecast chemical reactions by showing how the amount of valence electrons follows different patterns on the periodic table.
How is the number of valence electrons represented in the periodic table?The number of valence electrons in groups 1-2 and 13–18 rises by one from one element to the next throughout each row, or period, of the periodic table.
What are valence electrons and valence valence?The ability of an atom to make covalent bonds with other atoms is known as its "valency." Valence electrons, on the other hand, are the quantity of electrons required in a compound's entire outer shell in order for bonds to form.
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According to Beers Law, A-&bc; what should the slope and the intercept be in calibration curve for 'plot
If the route length is constant, the intercept of the calibration curve should be zero, and the slope should be proportional to the molar absorptivity times the path length.
What is the calibration graph for Beer's law's slope?Beer's law, which links absorbance to concentration, is represented by a linear function. The molar attenuation coefficient multiplied by the cuvette width, or pathlength—1 centimetre in this lab—gives you the slope of your calibration curve. To find the concentration, rearrange the linear solution.
According to Beer's Law, a solution's absorbance (A) is inversely proportionate to its concentration.
A = εcl
The molar absorptivity () times the route length (l) are represented by the calibration curve's slope (m):
m = εl
If the route length is constant, the calibration curve's intercept (b) should be zero because there shouldn't be any absorbance at zero concentration:
b = 0
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Need help with problem
The number of moles of CO contained in the 20.0 L tank at 93 °C and 4.52 atm is 3.01 moles
How do i determine the number of mole contained in the tank?Ideal gas equation is given as follow:
PV = nRT
Where
P is the pressureV is the volumen is the number of moleR is the gas constantT is the temperatureWith the above formula, we can obtain the number of mole of CO in the tank. This is shown below:
Volume (V) = 20.0 L Temperature of gas (T) = = 93 °C = 93 + 273 = 366 KPressure of gas (P) = 4.52 atmGas constant (R) = 0.0821 atm.L/molKNumber of mole of CO (n) =?PV = nRT
4.52 × 20 = n × 0.0821 × 366
Divide both sides by (0.0821 × 366)
n = (4.52 × 20) / (0.0821 × 366)
n = 3.01 moles
Thus, we can conclude that the number of mole of the gas is 3.01 moles. The correct answer is the 3rd option
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Identify the system and surroundings!! And c, d, and e
The candle and the wax represent the structure. Everything that is not a part of the flame or the wax, such as the air, items in the room, and anything else, is considered to be the surroundings. As the liquid wax solidifies, heat is transferred from the wax to the environment.
What kind of response occurs when candle wax melts?Wax fire causes a chemical change while wax melting causes a physical change: Wax changes from a solid to a liquid on its own when it melts. Only the physical state of a substance alters in the described procedure.
When candle wax melts, where does it go?The New York Times claims that the majority of a candle's material truly evaporates into the air. Actually, the wax rises as it begins to melt and pool around the cotton flame of the candle.
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Keq= 798 for the reaction:
2SO2 (g) + O2 (g) ⇌ 2SO3 (g)
In a particular mixture at equilibrium, [SO2]= 4.20 M and [SO3]=11.0 M.
Calculate the equilibrium concentration of O2 ([O2]) this mixture.
It's easy
Explanation:
We can use the equilibrium constant expression to calculate the equilibrium concentration of O2:
Kc = [SO3]^2 / ([SO2]^2 [O2])
At equilibrium, the value of Kc is constant, so we can use the equilibrium concentrations of SO2 and SO3 to solve for [O2]:
Kc = [SO3]^2 / ([SO2]^2 [O2])
Kc = (11.0 M)^2 / ((4.20 M)^2 [O2])
Simplifying:
[O2] = (11.0 M)^2 / (Kc (4.20 M)^2)
The value of Kc for this reaction is 4.67 × 10^1, as determined by experiment.
[O2] = (11.0 M)^2 / (4.67 × 10^1 (4.20 M)^2)
[O2] = 0.153 M
Therefore, the equilibrium concentration of O2 in this mixture is 0.153 M.
What is the pH of an aqueous solution with a hydrogen ion concentration of [H+]=3.1×10−9 M?
the pH of the aqueous solution is 8.51 with a hydrogen ion concentration of [H+]=3.1×[tex]10^-9[/tex]M
The pH of the aqueous solution can be calculated using the formula:
pH = -log[H+]
where [H+] is the hydrogen ion concentration of the solution.
Substituting the given value, we get:
pH = -log(3.1×[tex]10^-9[/tex])
pH = 8.51
An aqueous solution is one in which water serves as the solvent. It is utilised in a variety of applications, including analytical chemistry, biochemistry, and industrial chemistry. It is the most prevalent kind of solution used in chemical reactions. Water serves as both the solvent and the solute in an aqueous solution, where the solute is often a solid, liquid, or gas. Due to its high polarity and capacity to make hydrogen bonds with other molecules, water is an excellent solvent that can dissolve a variety of materials, including polar molecules and ionic compounds. Acid-base reactions, redox reactions, and precipitation reactions are just a few of the numerous chemical processes that take place in aqueous solutions. A variety of variables can have an impact on an aqueous solution's characteristics.
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ASAP PLEASE!!!
1. Claim: How are elements arranged on the periodic table in terms of valence
electrons? (2 points)
2. Evidence: Use the Element symbol provided to create a Bohr/ Orbital Model for
each. Use the PhET simulation to work through each. Complete the table below.
Include a picture of each that you either snip from the simulation or draw. We
The periodic table is arranged in such a way that elements with similar valence electron configurations are placed in the same group or column.
How are elements arranged on the periodic table in terms of valence?Valence electrons are the outermost electrons in an atom, and they play a critical role in determining the chemical properties of an element.
The elements in each column of the periodic table have the same number of valence electrons, which gives them similar chemical properties
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Explain the difference between an open and closed system in terms of matter and energy.
Explanation:
The stovetop example would be an open system, because heat and water vapor can be lost to the air. A closed system, on the other hand, can exchange only energy with its surroundings, not matter.
Calculate the number of atoms in a 7.08 x 103 g sample of aluminum.
Answer:
There are 4.59×1024 4.59 × 10 24 atoms of Al in 7.63 moles of Al.
Must be Correct 50 POINTS
The chemical formula for the product.
(a)Orbital diagram for Li:
1s² 2s¹
Orbital diagram for S:
1s² 2s² 2p⁶ 3s² 3p⁴
Lewis structure for Li:
Li: [Li]+
Lewis structure for S:
:S:::S:
Combination of Li and S:
Li₂S
(b)
Orbital diagram for Ca:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Orbital diagram for Cl:
1s² 2s² 2p⁶ 3s² 3p⁵
Lewis structure for Ca:
Ca: [Ca]²⁺
Lewis structure for Cl:
:Cl:
Combination of Ca and Cl:
CaCl₂
(c)
Orbital diagram for K:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
Orbital diagram for Cl:
1s² 2s² 2p⁶ 3s² 3p⁵
Lewis structure for K:
K: [K]+
Lewis structure for Cl:
:Cl:
Combination of K and Cl:
KCl
(d) Orbital diagram for Na:
1s² 2s² 2p⁶ 3s¹
Orbital diagram for N:
1s² 2s² 2p³
Lewis structure for Na:
Na: [Na]+
Lewis structure for N:
:N:::N:
Combination of Na and N:
Na₃N
An orbital diagram is a visual depiction of the electrons located in an atom's or molecule's orbitals. Each electron is represented by an arrow, while each orbital is illustrated by a line.
The two electrons in each orbital's two lines are drawn in pairs to represent their opposing spins. Lewis structures, on the other hand, are schematics that display the interactions between the atoms in a molecule as well as any potential lone pairs of electrons.
Each atom's valence electrons are shown as dots, and the connections between atoms are shown as lines. The kind of bond that can be created between two elements depends on the number of valence electrons.
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How many percent by mass of mercury are there in a sample of tap water with a mass of 750 g containing 2.2g of Hg?
Answer:
Divide the mass of the water lost by the mass of hydrate and multiply by 100. The theoretical (actual) percent hydration (percent water) can be calculated from the formula of the hydrate by dividing the mass of water in one mole of the hydrate by the molar mass of the hydrate and multiplying by 100.
Given the thermochemical equations
X2+3Y2⟶2XY3Δ1=−370 kJ
X2+2Z2⟶2XZ2Δ2=−130 kJ
2Y2+Z2⟶2Y2ZΔ3=−220 kJ
Calculate the change in enthalpy for the reaction.
4XY3+7Z2⟶6Y2Z+4XZ2
The change in enthalpy for the given reaction is +330 kJ.
To calculate the change in enthalpy for the reaction:
4XY3 + 7Z2 ⟶ 6Y2Z + 4XZ2
we need to use the Hess's Law, which states that if a chemical reaction can be expressed as the sum of several stepwise reactions, the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the individual reactions.
We can write the reaction in terms of the given thermochemical equations as follows:
4XY3 ⟶ 2X2 + 6Y2 (reverse of equation 1, with ΔH = +370 kJ)
2X2 + 4XZ2 ⟶ 8XY3 (multiply equation 2 by 2, with ΔH = -2×130 kJ = -260 kJ)
2Y2 + Z2 ⟶ 2Y2Z (reverse of equation 3, with ΔH = +220 kJ)
Adding these three equations gives:
4XY3 + 7Z2 ⟶ 6Y2Z + 4XZ2 (with ΔH = 370 kJ - 260 kJ + 220 kJ = +330 kJ).
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The following chemical reaction takes place in aqueous solution: Fe2(SO4)3 (aq)+ 3K2S(aq) → Fe2S3(s)+ 3K2SO4(aq)
Write the net ionic equation for this reaction.
The net ionic equation for the reaction is:
2Fe3+(aq) + 3S2-(aq) → Fe2S3(s)
What is Ionic Equation?
An ionic equation is a chemical equation that shows the chemical species as their respective ions in a solution. In other words, an ionic equation only includes the ions that participate in the chemical reaction, and excludes any spectator ions that do not participate in the reaction.
The net ionic equation shows only the species that participate in the reaction and omits the spectator ions (ions that appear on both sides of the equation without undergoing a change).
First, let's write the balanced chemical equation for the reaction:
Fe2(SO4)3(aq) + 3K2S(aq) → Fe2S3(s) + 3K2SO4(aq)
To write the net ionic equation, we need to identify the ions that are present in aqueous solution and that participate in the reaction. These are:
Fe2+(aq), SO42-(aq), K+(aq), and S2-(aq)
The balanced ionic equation is:
2Fe3+(aq) + 3SO42-(aq) + 6K+(aq) + 3S2-(aq) → Fe2S3(s) + 3K2SO4(aq)
To obtain the net ionic equation, we eliminate the spectator ions, which are the potassium and sulfate ions that appear on both sides of the equation:
2Fe3+(aq) + 3S2-(aq) → Fe2S3(s)
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How are hybrid and electric cars related to air pollution
Why do sex-linked traits follow different patterns of inheritance than other
traits?
Answer: Sex-linked traits are different from other traits because they are located on the sex chromosomes. Since males and females have different numbers of these chromosomes, the inheritance of sex-linked traits is different between the two sexes. This means that certain traits are more likely to be expressed in males than in females, and that females can inherit these traits from both parents while males can only inherit them from their mother.
Explanation: Sex-linked traits follow different patterns of inheritance than other traits because they are located on the sex chromosomes (X and Y) rather than on the autosomes (non-sex chromosomes). Since males have one X and one Y chromosome, and females have two X chromosomes, the inheritance of sex-linked traits is affected by the sex of the individual and the number of copies of the gene present.
The X chromosome contains many more genes than the Y chromosome and therefore, most sex-linked traits are inherited in a dominant or recessive manner on the X chromosome. In females, the presence of two copies of the X chromosome allows for a greater range of genetic variability, as both copies can potentially express different alleles. In males, however, the presence of only one X chromosome means that any alleles on that chromosome will be expressed, regardless of whether they are dominant or recessive. This is why sex-linked traits are more commonly expressed in males than in females.
Additionally, since males only inherit one X chromosome from their mother, they can only inherit X-linked traits from her. Females, on the other hand, inherit one X chromosome from each parent, which means they can inherit X-linked traits from both their mother and father. This can affect the frequency and distribution of certain sex-linked traits in a population.
Overall, the unique inheritance patterns of sex-linked traits are a consequence of their location on the sex chromosomes and the differences in chromosome inheritance between males and females.
If electrons jump from a lower energy shell to a higher energy shell, they are said to be ____
Answer:
they are said to be excited.
Explanation:
excitation is a fundamental concept in atomic physics that helps explain many of the properties and behaviors of matter on both the macroscopic and microscopic scales.
Calculate the change in energy using bond energies for the following reaction. Explain if the reaction is endothermic or exothermic. Check the bond energy chart for reference
The bond energy is -183 kJ/ mol for the given reaction and bond energies for the reaction. The reaction is exothermic.
What is bond energy ?Atoms bond together to create compounds because doing so allows them to achieve lower energies than they would have as individual atoms. A quantity of energy equivalent to the difference between the energies of the bonded and separated atoms is released, typically as heat. That is, linked atoms have less energy than individual atoms. Energy is always released when atoms combine to form a compound, and the compound has a reduced overall energy.
When a chemical reaction happens, molecular bonds are broken and new bonds are formed, resulting in the formation of new molecules.
Change is energy(ΔE) = ΣΔBE (Products) - ΣΔBE (Reactant)
ΔE = (432+ 239) - 2×427
ΔE = -183 kJ/ mol
Therefore it is exothermic reaction.
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How many liters of oxygen are needed to exactly react with 17.5 g of methane, CH4, at
STP? (Hint: you must calculate the number of moles of CH4 and look at the reaction
stoichiometry first)
CH4(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(l)
Formation of the Solar System Lab Report
Instructions: In this virtual lab, you will investigate the law of universal gravitation by
manipulating the size of the ster and the positions of planets within Solar System X. Record your
hypothesis and results in the lab report below. You will submit your completed report.
Name and Tide:
Include your name, instructor's name, date, and name of lab
Awi Ulivar, Mrs. Harmon, 3/30/21, Formation of the solar system lab report
Objectives():
is your own words, what is the purpose of this lab?
Hypothesia:
In this section, please inchade the if the statements you developed during your lab activity
These statements reflect your predicted outcomes for the experiment.
If the mass of the sun is Is at least
If the mass of the sun is 2x, at least one planet will fall into the habitable rone if I place a planet
and all planets will orbit the sun successfully.
arbits
If the
e planet will fall into the habitable zone if I place a planet
and all planets will orbit the sun successfully.
the sun i
at least one planci will fall into the habitable zone if I place a plant
and all planets will orbit the sun successfully.
Procedure:
The materials and procedures are listed in your virtual lah. You do not need to repeat them here.
However, you should note if you experienced any errors or other factors that might affect your
Using the summary quvons at the end of your virtual lab activity, please clearly define the
dependent and independent variables of the experiment
Data:
Record your observation statements from Space Academy.
When the mass of the sun is larger, Farth moves around the sun at a
pace.
When the mass of the sun is smaller, Farth moves around the sun at a
pace.
When Farth is closer to the sun, its orbit becomes
When Farth is farther from the sun, its orbit becomes
Example:
'smas I
MAT'S THIS
I Trial One
MAT'S HILL
1-Tial Two
For each trial, record the orbit manber of each planet from the sun. Be sure to indicate the
amber of planets in the habitable zone after each trial. Create a different configuration of
planets for each trial. An example has been supplied for you.
MAY
2x-Trial One
way's mass
2- Tial Two
mask
34-Trial One
WAY's mass
J-Tial Two
Orbit
Number
Planet One
Orbit
Number
Planet
Two
(faster, slower)
3
(faster, slower)
(faster, slower)
(faster, slower)
Orbit
Orbit
Number Number
Planet Planet
Three
Four
Number of Number of
planets in planets left
the
habitable
PODE
successful
orbit
Conclusion:
Your conclusion will include a ummary of the lab results and an interpretation of the results
Please awwer all questions in complete sentences using your own work
1. Using two to three sentences, semmarize what you investigated and observed in this lab
2. You completed three terra forming trials. Describe the how the sun's mass affects planets
in a solar system, Use data you receeded to support your conclusions
3. In this simulation the masses of the planets were all the same do you think of the masses of the planets were different it would affect the results why or why not?
4. How does this simulation demonstrate the law of universal gravitation
5. It is year 2085 and the world population has grown at an alarming rate as a space explorer you have been sent on a terraforming mission into space your mission to search for a habitable planet for humans to colonize in addition to planet earth you found a planet you believe would be habitable and now need to report beach your findings describe the new planet and why it would be perfect for maintaining human life.
According to the stimulation, if the bulk of the plants is the same, there will be no change.
What makes planet masses different?Planets have varying masses because they are formed of diverse materials, and their mass dictates their thickness and thinness.
The weight of an item is determined by its mass and the strength with which gravity pulls on it. The strength of gravity is proportional to the distance between two objects. As a result, the same thing weights differently on various planets.
The mass indicates the influence of gravity as well as the density of the atmosphere. If the masses are the same, all planets will be the same size, and many will be incapable of supporting life.
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I NEED THIS DONE TODAY !!!!!!!!Electromagnetic Spectrum Lab Report
Destructions: In this virtual lab, you will use a virtual spectrometer to analyze astronomical
bodies in space. Record your hypothesis and spectrometric recular in the lab report below. You
will submit your completed report to your butructor.
Name and Title:
Include your name, instru
1
and name of lab.
Objectives (1):
In your own words, what is the purpose of this lab?
Hypothesis:
In this section, please include the predictions you developed during your lab activity. These
statements reflect your predicted outcomes for the experiment.
Procedure:
The materials and procedures are listed in your virtual lab. You do not need to repeat them here.
However, you should note if you experienced any errors or other factors that might affect your
outcome. Using your summary questions at the end of your virtual lab activity, please clearly
define the dependent and independent variables of the experiment.
Data:
Record the elements present in each unknown astronomical object. Be sure to indicate "yes" or
"no" for each element.
Hydrogen Helium Lithium Sodiam Carbon
Moon One
Moon Two
Planet One
Planet Two
Nitrogen
Conclusion:
Your conclusion will inchade a summary of the lab results and an interpretation of the results.
Please answer all questions in complete sentences using your own words.
1. Using two to three sentences, summarize what you investigated and observed in this lab
2. Astronomers use a wide variety of technology to explore space and the electromagnetic
spectrum; why do you believe it is essential to use many types of equipment when
studying space?
3. If carbon was the most common element found in the moons and planets, what element is
missing that would make them splat to Earth? Explain why. (Hint: Think about the
carbon cycle)
4.
We know that the electromagnetic spectrum uses wavelengths and frequencies to
determine a lot about outer space. How does it help us find out the make-up of stars?
5. Why might it be useful to determine the elements that a planet or moon is made up of?
PLEASE MAKE SURE YOU ANSWER THE HYPOTHESIS AND PROCEDURE QUESTION!!!!
Below contains the complete lab report on electromagnetic spectrum
The Lab ReportName: [Your Name]
Title: Electromagnetic Spectrum Lab Report
Instructor: [Instructor's Name]
Objectives:
The purpose of this lab is to analyze the elemental composition of different astronomical bodies using a virtual spectrometer and understand the importance of the electromagnetic spectrum in astronomical research.
Hypothesis:
I predict that the moons and planets will have varying compositions of elements, with hydrogen and helium being more common in gaseous bodies and heavier elements like carbon and nitrogen more common in rocky bodies.
Dependent variable: Presence of elements in astronomical bodies
Independent variable: Astronomical bodies (Moon One, Moon Two, Planet One, Planet Two)
Data:
[Please input your data for each object as per your virtual lab results]
Conclusion:
In this lab, I investigated the elemental composition of four different astronomical bodies using a virtual spectrometer and observed the presence or absence of various elements.
It is essential to use many types of equipment when studying space because different instruments can detect and analyze different aspects of the electromagnetic spectrum, providing a comprehensive understanding of the universe.
To make these moons and planets similar to Earth, oxygen would need to be present as it is a vital component of the carbon cycle and essential for life as we know it.
The electromagnetic spectrum helps us find out the makeup of stars by analyzing the emitted light, which contains information about the elements and their abundance within the star.
Determining the elements that a planet or moon is made up of helps us understand their formation, potential for life, and possible resources for future exploration or colonization.
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What is the molarity of 30.0 mL of hydrochloric acid solution after 15.0 mL of a 3.00 M solution has been diluted?
___ M (Answer Format X.X)
Answer:
To find the molarity of the new solution, we need to use the equation:
M1V1 = M2V2
Where:
M1 = initial molarity = 3.00 M
V1 = initial volume = 15.0 mL
M2 = final molarity (what we're solving for)
V2 = final volume = 30.0 mL
Rearranging the equation to solve for M2:
M2 = (M1V1)/V2
M2 = (3.00 M * 15.0 mL)/30.0 mL
M2 = 1.50 M
Therefore, the molarity of the new solution is 1.50 M.
Answer:
1.00 M
Explanation:
Molarity is defined as the number of moles of solute per liter of solution. When a solution is diluted, the number of moles of solute remains constant, but the volume of the solution increases. Therefore, the molarity of the solution decreases.
In this case, the initial number of moles of solute in the 15.0 mL of 3.00 M hydrochloric acid solution is (15.0 mL) * (3.00 mol/L) * (1 L/1000 mL) = 0.045 mol.
After dilution, the volume of the solution increases to 30.0 mL + 15.0 mL = 45.0 mL. The molarity of the diluted solution is (0.045 mol) / (45.0 mL) * (1000 mL/L) = 1.00 M.
So, the molarity of 30.0 mL of hydrochloric acid solution after 15.0 mL of a 3.00 M solution has been diluted is 1.00 M.
how many moles of helium gas are present in a 11.2l container at 298k and 1.35 atm the gas constant r =0.0821 atm/k mol
Answer
The first step is to use the ideal gas law equation: PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature.
Rearranging the equation to solve for n, we get:
n = PV/RT
Substituting the given values, we get:
n = (1.35 atm) x (11.2 L) / [(0.0821 atm·L/mol·K) x (298 K)]
n = 0.553 mol
Therefore, there are 0.553 moles of helium gas present in the 11.2L container at 298K and 1.35 atm.
Which of these prostheses is used to support blood flow through an artery?
OA. A nanotube
OB. A passive prosthesis
OC. A stent
OD. A pacemaker
Gallium is a solid metal at room temperature but melts at 29.9 °C. If you hold gallium in your hand, it melts from body heat. How much heat must 2.5 g of gallium absorb from your hand to raise its temperature from 25.0 °C to 29.9 °C? The specific heat capacity of gallium is 0.372 J/g
In order for 2.5 g of gallium to transform from a solid state at 25.0 °C to a liquid state at 29.9 °C, it would require absorbing 19.56 J of heat from your hand.
Why is gallium utilised in high temperature applications?Only gallium has a low melting point of 29.7°C and a high boiling point of 1500–2000°C. Together with these peculiar characteristics, it also exhibits undercooling (20 °C or below), which would make it a perfect thermometric liquid if not for its propensity to wet quartz and glass surfaces.
Q1 = m × c × ΔT
Q1 = 2.5 g × 0.372 J/g·°C × (29.9 °C - 25.0 °C)
Q1 = 5.58 J
Q2 = m × ΔH_fusion
Q2 = 2.5 g × 5.59 J/g
Q2 = 13.98 J
Q_total = Q1 + Q2
Q_total = 5.58 J + 13.98 J
Q_total = 19.56 J
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Select the two true statements about natural selection. Natural selection makes less advantageous variations become more advantageous over many generations. A population's environment affects the outcome of natural selection. Natural selection always makes a population gain new advantageous variations. Natural selection can change which variations are more common in a population over time. Submit
Answer:
The two true statements about natural selection are:
A population's environment affects the outcome of natural selection.
Natural selection can change which variations are more common in a population over time.
Natural selection acts on the existing variations within a population and favors those that confer a survival or reproductive advantage in a particular environment. Over time, the advantageous variations become more prevalent, and less advantageous ones may become less common or disappear from the population. However, natural selection does not necessarily create new variations; rather, it acts on the genetic variation that already exists within a population.
name two acids used in the manufacture of fertilizers
Two acids commonly used in the manufacture of fertilizers are sulfuric acid and phosphoric acid
What are the basic laboratory techniques or operations that are used in separating components of mixtures and explain why?
The basic laboratory techniques that are used for separating components of the mixture are:-
Distillation- This technique is used to separate the component from the mixture by heating the mixture and vaporising the element from the mix then condensing and storing them separately.Filtration- This technique is used in the laboratory to separate the element from the mixture with the help of filter paper. It is mainly used to separate impurities from the given liquid.Extraction- This technique is used to separate the element from the mixture with the help of a solvent that dissolves with the mixture and then separates the desired compound. Recrystallization- This technique is used for the separation of an element with help of a solvent that crystalizes the element from the mixture. This technique is mainly used to separate a solid from a mixture.To know more about The Separation of a mixture:
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A 100.0 mL sample of 0.10 M NH3 (weak base) is titrated with 0.10 M HNO3 (strong acid). Determine the pH of the solution after the addition of 50.0 mL of HNO3. The Kb of NH3 is 1.8 × 10-5.
To solve this problem, we need to use the concept of weak acid-base equilibrium and the Henderson-Hasselbalch equation. The reaction between NH3 and HNO3 can be written as:
NH3 + HNO3 → NH4+ + NO3-
Before any HNO3 is added, the NH3 solution is a weak base with the following equilibrium equation:
NH3 + H2O ⇌ NH4+ + OH-
where the Kb of NH3 is 1.8 × 10-5. At the start, we have 0.10 M NH3, and the concentration of OH- can be calculated using the Kb expression:
Kb = [NH4+][OH-]/[NH3]
[OH-] = Kb[NH3]/[NH4+] = 1.8 × 10^-5 × 0.10 / x, where x is the concentration of NH4+.
At the equivalence point, the moles of HNO3 added equals the moles of NH3 initially present, and the solution contains only NH4+ and NO3-. Therefore, the concentration of NH4+ is:
x = 0.10 - 0.05 = 0.05 M
At this point, all the OH- ions have been consumed by the HNO3, so the pH of the solution depends on the concentration of NH4+. The Henderson-Hasselbalch equation for a weak acid-base system is:
pH = pKa + log([base]/[acid])
where pKa is the negative logarithm of the acid dissociation constant (Ka) and [base]/[acid] is the ratio of the concentrations of the weak base and its conjugate acid.
For NH3, the conjugate acid is NH4+ and the pKa can be calculated as:
pKa = -log(Ka) = -log(1.8 × 10^-5) = 4.74
Plugging in the values, we get:
pH = 4.74 + log(0.05/0.05) = 4.74
Therefore, the pH of the solution after the addition of 50.0 mL of HNO3 is 4.74.
For each of the following equilibria, write the equilibrium constant expression for Kc.
1. BaSO4(s) <---->Ba2+(aq) + SO42-(aq)
2. CH3COOH (aq) + H2O (l) <--->CH3COO- (aq) + H3O+ (aq)
Equilibria are chemical reactions that happen with a change in the concentration of the reactants or products. If the forward reaction is favored, a greater concentration of the product will be formed than the reactant(s), and the reaction is said to be favored. If the reverse reaction is favored, a greater concentration of the reactant(s) will be formed and thus the reaction is said to be favored. An equilibrium constant (constant K), is a number that describes the ratio of products to reactants at an equilibrium. K is also referred to as the equilibrium coefficient.
Answer:
1. Kc = [Ba2+][SO42-]
2. Kc = [CH3COO-][H3O+]/[CH3COOH]
Explanation:
The equilibrium constant expression for Kc is the product of the concentrations of the products raised to their stoichiometric coefficients divided by the product of the concentrations of the reactants raised to their stoichiometric coefficients.
1. For the first equilibrium, BaSO4(s) <---->Ba2+(aq) + SO42-(aq), the equilibrium constant expression for Kc is: Kc = [Ba2+][SO42-].
2. For the second equilibrium, CH3COOH (aq) + H2O (l) <—>CH3COO- (aq) + H3O+ (aq), the equilibrium constant expression for Kc is: Kc = [CH3COO-][H3O+]/[CH3COOH].
Note that the concentration of water is not included in the expression because it is a pure liquid and its concentration is considered constant.
How many ions are formed during the dissociation of 500 molecules of carbonic acid, if it dissociates in the first degree by 20%, and in the second degree by 1%? Explain your answer.
The dissociation of 500 molecules of carbonic acid would produce 200 + 15 = 215 ions.
What is Dissociation?
Dissociation is a chemical process in which a compound breaks down into two or more simpler components, usually ions, when it is exposed to a suitable solvent or energy source such as heat or light. In other words, it is the separation of a molecule or compound into smaller particles such as atoms, ions, or radicals.
The dissociation of carbonic acid (H2CO3) in the first degree produces two ions (H+ and HCO3-) per molecule, while the dissociation in the second degree produces three ions (H+, CO32-, and HCO3-) per molecule.
If 500 molecules of carbonic acid dissociate in the first degree by 20%, then 20% of the molecules (0.2 x 500 = 100) will dissociate, producing 100 x 2 = 200 ions (H+ and HCO3-).
If 500 molecules of carbonic acid dissociate in the second degree by 1%, then 1% of the molecules (0.01 x 500 = 5) will dissociate, producing 5 x 3 = 15 ions (H+, CO32-, and HCO3-).
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