A 3.5 gram sample of a radioactive element was formed in a 1960 explosion of an atomic bomb at Johnson Island in the Pacific test site. The half-life of the radioactive element is 28 years. How much of the original sample will remain in the year 2030? Choose the closest.
DO NOT GUESS, ONLY COMMENT IF YOU KNOW
Answer : The correct answer for amount of radioisotope remain in 2030 is 0.619 g .
Radioactive Decay is emission of radiations ( in form of alpha , beta particle etc ) by unstable atom .
Radioactive decay is FIRST ORDER reaction . So , the equation of first order can be used to find decay constant , amount of radioisotopes or half life .
The equation for radioactive decay is given as :
[tex] ln (\frac{N}{N_0}) = -k * t [/tex]
Where : N = amount of radioisotope at time t
N₀ = amount of radioisotope initially present
k = decay constant t = time
Half life :
It is time when amount of radioisotope decrease to 50 % of its original amount . Half life [tex] (T_\frac{1}{2} ) [/tex] and decay constant can be related :
[tex] T_\frac{1}{2} = \frac{ln 2 }{k} = \frac{0.693}{k} [/tex]
Following are the steps can be used to determine amount of radioisotope (N) :
1) To find decay constant :
Given : [tex] (T_\frac{1}{2} ) [/tex] = 28 yrs
Decay constant can be calculated using half life by plugging value in half life formula :
[tex] 28 yrs = \frac{0.693}{k} [/tex]
On multiplying both side by k
[tex] 28 yrs * k= \frac{0.693}{k} *k [/tex]
On dividing both side by 28 yrs
[tex] \frac{28 yrs * k}{28 yrs} = \frac{0.693}{28 yrs} [/tex]
k = 0.02475 yrs⁻¹
2) To find amount of radioisotope (N):
Given : Amount of radioisotope originally present = 3.5 g
Time = 2030 - 1960 = 70 yrs
decay constant = 0.02475 yrs⁻¹
Amount of radioisotope (N) = ?
Plugging these values in the formula as:
[tex] ln (\frac{N}{3.5 } ) = - 0.02475 yrs^-^1 * 70 yrs [/tex]
[tex] ln (\frac{N}{3.5 } ) = - 1.7325 [/tex]
[tex] ln\frac{N}{No} [/tex] can be converted using the formula ( [tex] ln (\frac{a}{b} ) = ln a - ln b [/tex] )
ln N - ln (3.5 ) = - 1.7325
(ln 3.5 = 1.253 )
ln N -1.253 = -1.7325
Adding both side 1.253
ln N -1.253 + 1.253 = -1.7325 + 1.253
ln N = -0.4795
Taking anti ln of -0.4795
N = 0.619 g
Hence amount of radioisotope remained in 2030 is 0.619 g
What is the ground-state electron configuration for the element cobalt (z = 27)?
The ground-state electron configuration for cobalt (Z = 27) is [Ar] 3d7 4s2.
Explanation:The ground-state electron configuration for the element cobalt (Co), which has an atomic number (Z) of 27, is as follows:
Co: [Ar] 3d74s2
This configuration indicates that cobalt has 2 electrons in the outermost 4s subshell and 7 electrons in the 3d subshell after the [Ar] noble gas core.
The ground-state electron configuration for the element cobalt (Z = 27) is 1s²2s²2p⁶3s²3p⁶4s²3d⁷. Co has 27 protons, 27 electrons, and 33 neutrons. The electron configuration represents the distribution of electrons in the energy levels and orbitals of an atom.
Find the new concentration of a solution if 25.0 mL of water is added to 125.0 mL of 0.150 M NaCl solution. What is the final volume? mL
Answer:
150.0 is the final volume
next question is a
and the next is 0.125 M
Explanation:
got it right in edge in 2020
To calculate the new concentration of NaCl solution after dilution, the final volume of the solution is determined to be 150.0 mL by adding the initial volume and the volume of water added. Using the molarity equation, the new concentration is found to be 0.125 M.
Explanation:To find the new concentration of the NaCl solution after dilution, we use the concept of molarity and the principle of conservation of mass. The amount of solute (NaCl in this case) stays the same, but the volume increases when more solvent (water) is added.
The initial molarity (Mi) of the NaCl solution is 0.150 M and the initial volume (Vi) is 125.0 mL. The volume of water added is 25.0 mL.
The final volume (Vf) is the sum of the initial volume and the volume of water added:
Vf = Vi + volume of water added
Vf = 125.0 mL + 25.0 mL
Vf = 150.0 mL
The new concentration Cf can be calculated using the formula:
Ci × Vi = Cf × Vf
(0.150 M) × (125.0 mL) = Cf × (150.0 mL)
Cf = (0.150 M × 125.0 mL) / 150.0 mL
Cf = 0.125 M
The final volume of the solution is 150.0 mL.
The compound aluminum acetate is a strong electrolyte. write the reaction when solid aluminum acetate is put into water:
When solid aluminum acetate (Aluminum Ethanoate) is put into water, it dissociates into its constituent ions, resulting in the following reaction:
Aluminum Acetate (solid) → Aluminum ions [tex]\rm (Al^3^+)[/tex] + Acetate ions [tex]\rm (CH_3COO^-)[/tex]
When solid aluminum acetate (also known as aluminum ethanoloate) is added to water, aluminum ions [tex]\rm (Al^3^+)[/tex] and acetate ions[tex]\rm (CH_3COO^-)[/tex]are produced. The attraction between the ions and the polar water molecules causes this separation. Hydration is the process through which water molecules surround these ions.
Due to the presence of freely moving ions that promote the flow of electric current, the resulting solution develops into a powerful electrolyte that can conduct electricity. Aluminum acetate dissociates and ionizes in water, which contributes to its function as a powerful electrolyte in aqueous solution and facilitates a variety of chemical and electrochemical reactions.
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The isotope lithium-7 has a mass of 7.0160 atomic mass units, and the isotope lithium-6 has a mass of 6.0151 atomic mass units. given the information that 92.58 percent of all lithium atoms found in nature are lithium-7 and 7.42 percent are lithium-6, calculate the atomic mass of lithium, li (atomic number 3).
A mixture of 100 g of k2cr207 and 200 g of water is stirred at 60 °c until no more of the salt dissolves. the resulting solution is poured off, leaving the undissolved solid behind. the solution is now cooled to 20°c. what mass of k2cr207 crystallizes from the solution during the cooling?
No K₂Cr₂O₇ will crystallize out of the solution during cooling.
What is crystallization?Crystallization is a separation technique used to purify a solid substance by selectively dissolving it in a suitable solvent at a high temperature and then cooling the solution to obtain pure crystals of the solute.
Given:
The solubility of K₂Cr₂O₇ in water at 60°C is 127 g/100 mL, and at 20°C is 13.9 g/100 mL.
Dissolved 100 g of K₂Cr₂O₇ in 200 g of water, which is 200 mL of water.
At 60°C, the solution can dissolve 127 g/100 mL × 2 L
= 254 g of K₂Cr₂O₇.
100 g of K₂Cr₂O₇, the solution is saturated and no more of the salt can dissolve.
When the solution is cooled to 20°C, the solubility of K₂Cr₂O₇ is only 13.9 g/100 mL.
The amount of water in the solution at 20°C is 200 mL. The maximum amount of K₂Cr₂O₇ that can remain in solution at this temperature is:
13.9 g/100 mL × 2 L = 278 g
Dissolved 100 g of K₂Cr₂O₇ in the solution, the amount that will crystallize out is:
100 g - 278 g = -178 g
This result is negative, indicating that all the K₂Cr₂O₇ will remain in solution at 20°C.
Therefore, no K₂Cr₂O₇ will crystallize out of the solution during cooling.
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help!!
The electron sea is responsible for which of the following properties?
A. All of these
B. Malleable
C. Ductile
D. Conducting electricity and heat
Answer:
D.Conducting electricity and heat
Explanation:
Metal : It is defined as that substance which is good conductor of electricity and heat. Metal have ductile and malleable property.In metal, atoms are held together by metallic bonds .The valence electrons from s and p orbital are delocalised and they form sea of electrons that surround the positively charged nuclei of the interacting metal ion.Then , the electrons are freely move throughout the space between atomic nuclei.
Due to availability of free electrons, metal conduct electricity and heat.
Therefore, the electron sea is responsible for conducting electricity and heat .
What are the products of the chemical reaction that occurs when zinc metal is added to an aqueous solution of hydrochloric acid?
The equilibrium constant for the reaction sr(s) + mg2+(aq) ⇌ sr2+(aq) + mg(s) is 3.69 × 1017 at 25°c. calculate e o for a cell made up of sr / sr2+ and mg / mg2+ half-cells.
To calculate the standard electrode potential (E°) for a cell composed of Sr/Sr²⁺ and Mg/Mg²⁺ half-cells, use the Nernst equation with the given equilibrium constant value. The resulting E° is approximately 1.038 V.
To find the standard electrode potential (E°) for the cell, we can use the Nernst equation and the relationship between the equilibrium constant (Keq) and the standard electrode potential:
Nernst equation:
E° = (RT / nF) * ln(Keq)
Where:
R = 8.314 J/(mol·K)T = 298 K (since the temperature is 25°C)n = 2 (number of electrons transferred, as each Sr replaces an Mg)F = 96485 C/molPlugging in the values, we get:
E° = (8.314 * 298 / (2 * 96485)) * ln(3.69 × 1017)
Simplify the constants:
E° = (0.0257 V) * ln(3.69 × 1017)
Evaluating the natural logarithm:
E° = 0.0257 * 40.38
E° ≈ 1.038 V
Therefore, the standard electrode potential (E°) for the cell is approximately 1.038 V.
All changes in chemistry are chemical? True or false?
A sample of a compound contains 32.0g C and 8.0g H. It’s molar mass is 30.0/mol. What is the compounds molecular formula?
Calculate the freezing point of a 0.08500 m aqueous solution of nano3. the molal freezing-point-depression constant of water is 1.86°c/m. remember to include the value of i.
Answer : The freezing point of a solution is, [tex]0.32^oC[/tex]
Explanation :
First we have to calculate the Van't Hoff factor (i) for [tex]NaNO_3[/tex].
The dissociation of [tex]NaNO_3[/tex] will be,
[tex]NaNO_3\rightarrow Na^++NO_3^-[/tex]
So, Van't Hoff factor = Number of solute particles = [tex]Na^++NO_3^-[/tex] = 1 + 1 = 2
Now we have to calculate the freezing point of a solution.
Formula used for lowering in freezing point :
[tex]\Delta T_f=i\times k_f\times m[/tex]
or,
[tex]T_f^o-T_f=i\times k_f\times m[/tex]
where,
[tex]\Delta T_f[/tex] = change in freezing point
[tex]T_f[/tex] = temperature of solution = ?
[tex]T^o_f[/tex] = temperature of pure water = [tex]0^oC[/tex]
[tex]k_f[/tex] = freezing point constant = [tex]1.86^oC/m[/tex]
m = molality = 0.08500 m
i = Van't Hoff factor = 2
Now put all the given values in this formula, we get the freezing point of a solution.
[tex]0^oC-T_f=2\times (1.86^oC/m)\times 0.08500m[/tex]
[tex]T_f=0.32^oC[/tex]
Therefore, the freezing point of a solution is, [tex]0.32^oC[/tex]
How many carbon-carbon sigma bonds are present in each of the following molecules: benzene, cyclobutane?
Final answer:
Benzene has six carbon-carbon sigma bonds because each carbon atom forms two sigma bonds with its adjacent carbon atoms. Cyclobutane has four carbon-carbon sigma bonds since it is a four-membered ring with each carbon bonded to two other carbons.
Explanation:
The question asks about the number of carbon-carbon sigma bonds in benzene and cyclobutane. Let's examine each molecule separately.
Benzene (C₆H₆)
In benzene, the carbons form a hexagonal ring and each carbon atom is bonded to two other carbon atoms. The structure of benzene is often depicted with alternating single and double bonds. However, due to resonance, the electrons are delocalized and each carbon-carbon bond is equivalent, resembling a structure with one-and-a-half bonds. Despite the presence of alternating double bonds, each carbon is involved in two sigma bonds with adjacent carbons and one sigma bond with a hydrogen atom, making a total of six carbon-carbon sigma bonds in benzene.
Cyclobutane (C₄H₈)
Cyclobutane is a four-membered ring where each carbon atom is bonded to two other carbons forming single bonds. Thus, for cyclobutane, there are four carbon-carbon sigma bonds, one between each pair of adjacent carbon atoms.
"at what gas temperature t e would the average translational kinetic energy of a helium atom be equal to that of an oxygen molecule in a gas of temperature 300 k"
The average translational kinetic energy of helium s equal to that of oxygen at [tex]\boxed{300\;{\text{K}}}[/tex] .
Further Explanation:
One of the states of matter is gas. In gases, the atoms and molecules have space between them and can easily move over each other hence gases are compressible. Gases neither have fixed shape nor volume. It occupies the shape and volume of the container. The examples of matter that are gases are nitrogen and carbon dioxide.
The kinetic theory is based on the following postulates:
1. Gas molecules have a large collection of individual particles with empty space between them and the volume of each particle is very small as compared to the volume of the whole gas.
2. The gas particles are in straight-line motion or random motion until they are not collided with the wall of the container or with each other.
3. The collision between the gas particles and the wall of the containers are an elastic collision that means molecules exchange energy but they don’t lose any energy during the collision. So the total kinetic energy is constant.
The formula to calculate the average translational kinetic energy of helium is as follows:
[tex]{{\text{E}}_{{\text{He}}}} = \frac{3}{2}{\text{k}}{{\text{T}}_{{\text{He}}}}[/tex] …… (1)
Here,
[tex]{{\text{E}}_{{\text{He}}}}[/tex] is the average translational kinetic energy of helium gas.
k is the Boltzmann constant.
[tex]{{\text{T}}_{{\text{He}}}}[/tex] is the absolute temperature of helium gas.
The formula to calculate the average translational kinetic energy of oxygen is as follows:
[tex]{{\text{E}}_{{{\text{O}}_{\text{2}}}}} = \frac{3}{2}{\text{k}}{{\text{T}}_{{{\text{O}}_{\text{2}}}}}[/tex] …… (2)
Here,
[tex]{{\text{E}}_{{{\text{O}}_{\text{2}}}}}[/tex] is average translational kinetic energy of oxygen gas.
k is the Boltzmann constant.
[tex]{{\text{T}}_{{{\text{O}}_{\text{2}}}}}[/tex] is absolute temperature of oxygen gas.
Since both gases have same average translational energy. So left-hand side of equation (1) and (2) becomes equal, and therefore right-hand side of both equations can be compared as follows:
[tex]\frac{3}{2}{\text{k}}{{\text{T}}_{{{\text{O}}_2}}} = \frac{3}{2}{\text{k}}{{\text{T}}_{{\text{He}}}}[/tex] …… (3)
Rearrange equation (3) to calculate [tex]{{\text{T}}_{{{\text{O}}_{\text{2}}}}}[/tex]
[tex]{{\text{T}}_{{{\text{O}}_2}}} = {{\text{T}}_{{\text{He}}}}[/tex] …… (4)
The value of [tex]{{\text{T}}_{{\text{He}}}}[/tex] is 300 K. So according to equation (4), [tex]{{\text{T}}_{{{\text{O}}_{\text{2}}}}}[/tex] also becomes 300 K.
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Answer details:
Grade: High School
Subject: Chemistry
Chapter: Ideal gas equation
Keywords: 300 K, helium, oxygen, average translational kinetic energy, k, Boltzmann constant, absolute temperature, gas, kinetic theory, 3/2 kT, same, equal.
When 5-hydroxypentanal is treated with methanol in the presence of an acid catalyst, 2-methoxytetrahydropyran is formed. draw the structure of the second intermediate in this reaction?
A solution of ammonia and water contains 2.60×1025 water molecules and 6.90×1024 ammonia molecules. how many total hydrogen atoms are in this solution
Consider 2NH3(g)+3CuO(s)→N2(g)+3Cu(s)+3H2O(g) 2NH 3 (g)+3CuO(s)→N 2 (g)+3Cu(s)+3H 2 O(g). What volume (in mL) of NH3 NH 3 is required to completely react 45.2 g of CuO at STP? Enter your solution as a numerical value with no units.
What is the standard gibbs free energy of formation, ∆gºf, of nh3(g) at 298 k?
The standard Gibbs free energy of formation of NH3(g) at 298 K is approximately -16.5 kJ/mol.
The standard Gibbs free energy of formation (ΔG°f) for ammonia (NH3(g)) at 298 K is approximately -16.5 kJ/mol. The standard Gibbs free energy of formation for a substance is the change in Gibbs free energy when one mole of the substance is formed from its elements in their standard states. The standard state for nitrogen gas (N2) is N2(g) at 1 bar pressure, and for hydrogen gas (H2) it is H2(g) at 1 bar pressure.
please note that the given value of -16.5 kJ/mol is an approximation, and it is recommended to refer to the latest thermodynamic data sources for the most accurate and up-to-date information.
How many unpaired electrons are present in a neon atom?
Electrons are a subatomic particle with a negative charge. They are also found present in atoms.
The number of unpaired electrons in a neon atom is zero.
A neon atom is part of the first twenty element and it is the tenth element in the series. Its chemical symbol is represented as Ne, its atomic number is 10 while the atomic mass is approximately 20.
It belongs to period 2 and found in the noble gas group. As the number of protons is the same as the electrons, therefore the number of electrons is 10.
In a neon atom, its electronic configuration is [He] 2S2 2p6. All electrons here are paired (in twos) with none unpaired. Therefore, the number of unpaired electrons in a neon atom is zero.
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n comparison to molecules that interact by London dispersion forces only, the melting point of similar-sized molecules forming hydrogen bonds would most likely be about the same. unpredictable. lower. higher.
Answer:
d
Explanation:
Select all that apply.
Which statements concerning this diagram are correct?
X = -ΔH
X = ΔH
Z = A.E.
Answer:
Correct answer is X = ΔH
Explanation:
The solubility product for chromium(iii) fluoride is ksp = 6.6 × 10–11. what is the molar solubility of chromium(iii) fluoride?
To determine the molar solubility of chromium(III) fluoride, we need to use the solubility product constant (Ksp) of 6.6 × 10⁻¹¹. The molar solubility of chromium(III) fluoride is 8.184 × 10⁻⁴M.
Explanation:To determine the molar solubility of chromium(III) fluoride, we need to use the solubility product constant (Ksp) of 6.6 × 10⁻¹¹ for chromium(III) fluoride. The Ksp expression is Ksp = [Cr³⁺][F⁻]³.
Let's assume the molar solubility of chromium(III) fluoride is x M. Since the stoichiometry of the balanced equation for its dissolution is 1:3 (one chromium ion per three fluoride ions), the equilibrium expression becomes Ksp = x(3x)³.
Now, we can set up the expression and calculate the molar solubility by solving the equation: Ksp = 108x⁴ = 6.6 × 10⁻¹¹. Solving for x gives x = 8.184 × 10⁻⁴ M. Therefore, the molar solubility of chromium(III) fluoride is 8.184 × 10⁻⁴ M.
what is the molarity of 10.0 g of kcl in 0.500 l of solution
Which statement describes a gas condensing into a liquid?
Answer:
The molecules get closer together and move more slowly.
Explanation:
from a gas to a liquid, the atoms or molecules of the substance do not change. Instead, the motion of the atoms or molecules in the substance determines its state of matter.
gas condenses to form a liquid, the molecules get closer together and move more slowly. If the molecules continue to slow down until they move so slowly that they can only vibrate against one another, then the substance becomes a solid.
A solution with a volume of 1.00 l is 0.450 m in ch 3 cooh(aq) and 0.550 m in ch 3 coona(aq). what will the ph be after 0.0800 mol of hcl is added to the solution?
What volume of 0.182 m na3po4 solution is necessary to completely react with 90.7 ml of 0.103 m cucl2?
Two of the substances in part 1 are ionic. which factors will result in a stronger ionic bond overall?
The factors that result in a stronger ionic bond are greater absolute charges and smaller ions. The similarity of ionic sizes can affect the bond's stability but doesn't directly make the bond stronger or weaker.
The following factors often affect an ionic bond's strength:
Greater absolute charges: Ionic bonds are more powerful when the positive and negative charges of the participating ions are greater. For instance, because the charges are higher in the former situation, the connection between a +2 ion (for instance, Ca²⁺) and a -2 ion (for instance, O₂) is stronger than between a +1 ion (for instance, Na⁺) and a -1 ion (for instance, Cl).
Ion bonds formed by smaller ions are frequently stronger. Ions can move closer to one another when they are smaller, which increases the electrostatic attraction between them.
Therefore, higher absolute charges and smaller ions produce an ionic bond that is stronger. Though it doesn't directly strengthen or weaken the binding, the similarity of the ionic sizes can have an impact on how stable the bond is.
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A stronger ionic bond is characterized by larger ionic charges and smaller ion sizes, resulting in greater attraction and higher lattice energy. For instance, a 2+ cation would form a stronger ionic bond with a chloride ion than a 1+ cation due to the greater charge.
The factors that will result in a stronger ionic bond overall include the magnitude of the charges and the size of the ions. A stronger ionic bond is formed when the ions involved have larger charges because larger charges result in a greater electrostatic force of attraction. Additionally, smaller ions form stronger bonds since they can get closer together, which increases the attraction between them. The lattice energy is a measure of the strength of ionic bonding.
Sodium chloride is an example of a substance with ionic bonds that result in high melting and boiling points due to the strong attractions. The strength of an ionic bond is directly proportional to the quantity of the charges and inversely proportional to the distance between the charged particles. For instance, a cation with a 2+ charge would form a stronger ionic bond with Cl− than a cation with a 1+ charge because of the greater charge magnitude.
2,2-dimethyl-4-propyloctane has how many secondary carbons? view available hint(s) 2,2-dimethyl-4-propyloctane has how many secondary carbons? five nine six seven
If 0.158 g of a white, unknown solid carbonate of a group 2A metal (M) is heated and the resulting CO2 is transferred to a 285 ml sealed flask and allowed to cool to 25 degrees Celsius, the pressure in the flask is 69.8 mmHg. What is the identity of the carbonate?
Why do reactions have activation energies?