The amount of Zn-71 left from a 100.0-gram sample after 7.2 minutes is 12.5 grams when the half-life of Zn-71 is 2.4 minutes.
The half-life of Zn-71 is 2.4 minutes, which means that after every 2.4 minutes, half of the Zn-71 atoms in the sample will
To Determine the number of half-lives that have passed.
Now divide the total time (7.2 minutes) by the half-life (2.4 minutes).
7.2 minutes / 2.4 minutes = 3 half-lives
Calculate the remaining amount of Zn-71 using the formula:
Final amount = Initial amount × (1/2)^number of half-lives
Plug in the values and calculate the remaining amount.
Final amount = 100.0 grams ×[tex](1/2)^3[/tex]
Final amount = 100.0 grams × (1/8)
Final amount = 12.5 grams
Therefore, The amount of Zn-71 left from a 100.0-gram sample after 7.2 minutes is 12.5 grams.
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State whether it would be worthwhile to investigate finding a catalyst to use in this reaction under standard conditions and explain why?.
Yes, it will be worthwhile to investigate finding a catalyst to use in this reaction under standard conditions because it is negative.
What is a Catalyst?This is a substance which speeds up the rate of a chemical reaction by lowering the activation energy.
ΔG being negative indicates a a slow reaction which is why a catalyst under standard conditions should be used.
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When a hydrogen atom is part of a molecular structure, it is always a ___________ atom.
Answer:
terminal
Explanation:
When a hydrogen atom is part of a molecular structure, it is always a terminal atom.
Consider a 175.7 g sample of the compound manganese(IV) perchlorate.
Using the formula Mn(ClO₄)₄ (MM = 452.74), What quantity in moles of oxygen are in 175.7 g of manganese perchlorate?
Answer:
6.21 moles O
Explanation:
To find the moles of oxygen, you need to (1) convert grams Mn(ClO₄)₄ to moles Mn(ClO₄)₄ (via molar mass) and then (2) convert moles Mn(ClO₄)₄ to moles O (via mole-to-mole ratio from formula subscripts). It is important to arrange the conversions/ratios in a way that allows for the cancellation of units.
Molar Mass (Mn(ClO₄)₄): 452.74 g/mol
1 Mn(ClO₄)₄ = 1 Mn and 4 Cl and 16 O
175.7 g Mn(ClO₄)₄ 1 mole 16 moles O
--------------------------- x ------------------- x --------------------------- = 6.21 moles O
452.74 g 1 mole Mn(ClO₄)₄
Use the following, balanced equation for the question below:
2Al(s) + 3CuCl₂(aq) → 3Cu(s) + 2AlCl3(aq)
How many moles of aluminum are needed to produce 50.0 grams of aluminum chloride?
Answer:
0.375 moles Al
Explanation:
To find the moles Al, you need to (1) convert grams AlCl₃ to moles AlCl₃ (via molar mass) and then (2) convert moles AlCl₃ to moles Al (via mole-to-mole ratio from equation coefficients). It is important to arrange the ratios/conversions in a way that allows for the cancellation of units. The final answer should have 3 sig figs to match the sig figs of the given value (50.0 g).
Molar Mass (AlCl₃): 26.982 g/mol + 3(35.453 g/mol)
Molar Mass (AlCl₃): 133.341 g/mol
2 Al(s) + 3 CuCl₂(aq) -----> 3 Cu(s) + 2 AlCl₃(aq)
50.0 g AlCl₃ 1 mole 2 moles Al
-------------------- x ------------------ x ----------------------- = 0.375 moles Al
133.341 g 2 moles AlCl₃
The oxidation number is often referred to as the _____. redox factor oxidation state spectator ion reducing factor
The oxidation number is often referred to as the oxidation state.
The number of electron/electrons which completely transferred and induced charged on an atom is called oxidation state of an atom. It is also describe as the number that is allocated to elements in a chemical combination. The number of electron that atoms in a molecule can share while forming chemical bonds with other atoms of a different elements. The oxidation number of the monoatomic (composed by atom) ion is the same as the charge of the ion.
The primary distinction between oxidation number versus oxidation state would be that the former refers to the charge that would be placed on the central atom of a coordination complex if every one of the connections around it were ionic bonds, while the latter relates to the number of electrons that an atom could either receive, lose, or share with some other atom.
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What is the concentration, in ppb, of
PCB's in a chemical spill, if there
are 6.0 x 10-5 g in 4,600 kg of soil?
Answer:
1ppm = 1 mg/kg
60460 = 0.13
0.13
Explanation:
Answer:0.013 ppb
Explanation:
The volume occupied by 0.4g of hydrogen gas at S.T.P is ________
{H=1.00, Molar volume at S.T.P =22.4dm^3
Answer:
4.48 dm^3
Explanation:
As given in the problem, the conversion factor for the molar volume of all gases is 22.4 dm^3/mole at STP. A mole of all ideal gases will occupy 22.4 liters (dm^3). Calculate the moles of hydrogen contained in 0.4 grams of the gas by dividing the mass by the molar mass of H2. H2 has a molar mass of 2 grams/mole.
(0.4 g)/(2 grams/mole) = 0.2 moles H2
(0.2 moles H2 at STP)*(22.4 dm^3/mole at STP) = 4.48 dm^3 (4.48 liters at STP)
A physical change involves a change in the identity o the sample.
O True
O False
A compound has an empirical formula of CH₂O. What is its molecular formula, if its molecular mass is 90 g/mol?
(C=12.01 amu, H=1.008 amu, O=16.00 amu)
A: C3H6O3
B: C9H1809
i need help asap, will give brainliest and 50 points, as this is on my final :)
Empirical formula mass
[tex]\\ \tt{:}\dashrightarrow 12+2+16[/tex]
[tex]\\ \tt{:}\dashrightarrow 30g/mol[/tex]
n:-
[tex]\\ \tt{:}\dashrightarrow \dfrac{Molecular\:mass}{Empirical\:mass}[/tex]
[tex]\\ \tt{:}\dashrightarrow \dfrac{90}{30}[/tex]
[tex]\\ \tt{:}\dashrightarrow 3[/tex]
Molecular formula
[tex]\\ \tt{:}\dashrightarrow n\times Empirical\: formula [/tex]
[tex]\\ \tt{:}\dashrightarrow 3(CH_2O)[/tex]
[tex]\\ \tt{:}\dashrightarrow C_3H_6O_3[/tex]
Calculate the number of atoms in 3 mol helium
Answer:
1.81 x 10²⁴ atoms He
Explanation:
You can find the amount of atoms by multiplying the given moles by Avogadro's Number. This number represents the amount of atoms per 1 mole. It is important to arrange the ratio in a way that allows for the cancellation of units.
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
3 moles He 6.022 x 10²³ atoms
-------------------- x -------------------------------- = 1.81 x 10²⁴ atoms He
1 mole
Is copper and silver nitrate a physical change or Chemical change
Explanation:
One of the most fascinating chemical experiments is the reaction between silver nitrate and copper wire in water. Characterised by fractal-like precipitates, this experiment is a stunning example of a simple redox reaction.
Copper reacting with silver nitrate is a chemical change. In a chemical change, new substances are formed with different chemical properties.
Copper (Cu) is a metal, and silver nitrate is a compound made of silver (Ag), nitrogen (N), and oxygen (O).When copper is added to silver nitrate, a reaction occurs. The copper atoms react with the silver nitrate molecules, resulting in the formation of new substances.
The reaction produces copper nitrate and silver (Ag) as products.Copper nitrate is a compound formed by the combination of copper, nitrogen, and oxygen, while silver remains unchanged.
The color of the solution changes, indicating a chemical reaction has taken place. Copper nitrate is usually a blue-green color, while silver is a metallic silver color.The chemical properties of the substances involved in the reaction are altered. Copper, being a metal, is malleable and conducts electricity, whereas copper nitrate is a compound and does not possess these properties.
Thus, the reaction between copper and silver nitrate is a chemical change because new substances with different properties are formed.
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Potassium carbonate dissolves as follows:
K2CO3(s) → 2k (aq) CO3^2-(aq).
What volume in liters of 1.0 m k2co3 solution is required to provide 0.50 moles of k (aq)?
The 0.25 volume in liters of 1.0 M [tex]K_{2}CO_{3}[/tex] solution is required to provide 0.5 moles of [tex]K[/tex](aq).
Calculation,
The Potassium carbonate dissolves as follows:
[tex]K_{2}CO_{3}(s)[/tex] → [tex]2K(aq) +[/tex][tex]CO_{3}^{-2} (aq)[/tex]
The mole ratio is 1: 2
It means, the 1 mole [tex]K_{2}CO_{3}[/tex] required to form 2 mole of [tex]K[/tex](aq).
To provide 0.5 mole of [tex]K[/tex](aq) = 1 mole ×0.5 mole /2 mole required by [tex]K_{2}CO_{3}[/tex].
To provide 0.5 mole of [tex]K[/tex](aq) ,0.25 mole required by [tex]K_{2}CO_{3}[/tex].
The morality of [tex]K_{2}CO_{3}[/tex] = 1 M = number of moles / volume in lit
The morality of [tex]K_{2}CO_{3}[/tex] = 1 M = 0.25 mole/ volume in lit
Volume in lit = 0.25 mole / 1 M = 0.25 mole/mole/lit = 0.25 lit
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The solubility of lead(II) chloride is 0.45 g/100 mL of solution. What is the Ksp of PbCl2?a. 8.5 ? 10^-6b. 4.2 ? 10^-6c. 1.7 ? 10^-5d. 4.9 ? 10^-2e. < 1.0 ? 10^-6
The solubility of lead(II) chloride is 0.45 g/100 mL of solution. The value of [tex]K_{sp}[/tex] of [tex]PbCl_{2}[/tex] is 1.7×[tex]10^{-5}[/tex] .
So, option C is correct one.
Calculation,
Number of moles of [tex]PbCl_{2}[/tex] = mass/molar mass = 0.45/278.1 = 1.618×[tex]10^{-3}[/tex] moles
Concentration of [tex]Pb^{+2}[/tex] and [tex]Cl^{-}[/tex] ion
Molarity of [tex]Pb^{+2}[/tex] = Number of moles of solute /volume in lit
Molarity of [tex]Pb^{+2}[/tex] = 1.618×[tex]10^{-3}[/tex] moles /0.1 lit = 0.0162 M
[tex]PbCl_{2}[/tex] → [tex]Pb^{+2}[/tex] + 2[tex]Cl^{-}[/tex]
For certain amount of [tex]Pb^{+2}[/tex] , twice this amount of [tex]Cl^{-}[/tex] ion formed.
The concentration of [tex]Cl^{-}[/tex] ion formed = 2× 0.0162 M = 0.0324 M
Now,
The solubility of lead(II) chloride of solution = 0.45 g/100 mL
[tex]K_{sp}[/tex] of [tex]PbCl_{2}[/tex] = [ [tex]Pb^{+2}[/tex] ][tex][Cl^{-}]^{2}[/tex] = 0.0162 ×[tex][0.0324 ]^{2}[/tex] = 1.7×[tex]10^{-5}[/tex] .
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Amines suitable for preparing buffers are often synthesized by treating ammonia with epoxides. Consider the following series of reactions, and draw the structure of compound B.
It is correct to state that Amines are suitable for preparing buffers are often synthesized by treating ammonia with epoxides. The relative structures of compound B are attached accordingly.
What is an Amine?Amine is a family of basic chemical compounds formed by replacing hydrogen with one or more monovalent hydrocarbon radicals.
Apart from medications and pharmaceuticals, amines are employed in the production of azo-dyes and nylon.
They are commonly employed in the development of crop protection, pharmaceutical, and water purification chemicals. They are also used in personal care products.
Ethanol amines are the most widely utilized form of amine on the global market.
It should be noted that ammonia attacks epoxides at the least substituted carbon to produce (A.)
The generated product is then made to react with another epoxide, resulting in the synthesis of successive products.
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A compound has a percent composition of 81.71% C and 18.29% H. What is the empirical formula of this compound?
Considering the definition of empirical formula, the empirical formula is C₃H₈.
Definition of empirical formulaThe empirical formula is the simplest expression to represent a chemical compound, which indicates the elements that are present and the minimum proportion in whole numbers that exist between its atoms, that is, the subscripts of chemical formulas are reduced to the most integers. small as possible.
Empirical formula in this caseIn this case, in first place you know the percent composition:
C: 81.71 %H: 18.29%Assuming a 100 grams sample, the percentages match the grams in the sample. So you have 81.71 grams of carbon and 18.29 grams of hydrogen H.
Then it is possible to calculate the number of moles of each atom in the molecule, taking into account the corresponding molar mass:
C: [tex]\frac{81.71 grams}{12\frac{grams}{mole} }[/tex]= 6.81 molesH:[tex]\frac{18.29 grams}{1\frac{grams}{mole} }[/tex]= 18.29 molesThe empirical formula must be expressed using whole number relationships, for this the numbers of moles are divided by the smallest result of those obtained. In this case:
C: [tex]\frac{6.81 moles}{6.81 moles}[/tex]= 1H:[tex]\frac{18.29 moles}{6.81 moles}[/tex]= 2.68 ≅ [tex]\frac{8}{3}[/tex]To express this relationship in the form of simple integers, it is necessary to multiply by a simple number to achieve this:
C: 1×3 =3 H:≅ [tex]\frac{8}{3}[/tex]×3= 8Therefore the C: H mole ratio is 3: 8
Finally, the empirical formula is C₃H₈.
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A solution contains 7.8% W/V ethanol. Express this in units of g/mL.
A solution that contains 7.8% W/V ethanol is equivalent to 0.078g/mL. Details about weights per volume can be found below.
How to convert W/V% to g/mL?Weights per volume is a unit for measuring density of a substance. It can be converted to g/mL using the following expression:
w/v% = g/100mL
According to this question, a solution contains 7.8% W/V ethanol. The equivalent of this in g/mL is as follows:
7.8% W/V = 7.8g/100mL
= 0.078g/mL
Therefore, a solution that contains 7.8% W/V ethanol is equivalent to 0.078g/mL.
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The statement, in a mixture of gases, the total pressure is the sum of the individual partial pressures of gases in the mixture paraphrases ________.
Dalton's law
States that the total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gas in the mixture.
What is Dalton's law of partial pressure ?Dalton's law, which states that a gas mixture's overall pressure is equal to the sum of its component gases' partial pressures. The pressure that each gas would produce if it occupied the same volume of the mixture by itself at the same temperature is known as the partial pressure.
The pressure that each gas would produce if it occupied the same volume of the mixture at the same temperature alone is referred to as the partial pressure.Learn more about Dalton's law of partial pressure here:
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Radiometric dating allows scientists to figure out the absolute age of an event.
A. What is a half-life?
B. Which of these four radioactive elements would you choose to date a specimen from the most recent epoch?
Half-life in geology is defined as the time it takes for a radioactive material or element to decay half its original quantity into a daughter radiogenic isotope.
From the radioactive elements listed the Carbon-14 would be most preferable for dating a specimen.
What is radiometric dating?Radiometric dating is defined as the process that is used by scientists to calculate the age of geologic materials.
From the data given in the table above, the radioactive element with the most recent half-life is carbon-14 being 5,730 years.
The uses os Carbon-14 include the following:
Used to measure the age of wood,Used to measure sources of chloride and the age of waterResearchers can use that decay as a kind of clock that allows them to peer into the past.Used in studying abnormalities of metabolism that underlie diabetes, gout, anemia, and acromegaly.The carbon-14 is preferably used for dating specimen because it is the most stable and accurately dates archaeological artifacts.
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In the reaction catalyzed by the pyruvate dehydrogenase complex, the two carbons constituting the acetyl group are.
In the reaction catalyzed by the pyruvate dehydrogenase complex, the two carbons constituting the acetyl group are oxidized by NAD+ while attached to the lipoamide.
Pyruvate dehydrogenase influencing the reaction:A multienzyme complex called pyruvate dehydrogenase (PDH) catalyzes the oxidative conversion of pyruvate into acetyl coenzyme A (CoA), carbon dioxide (CO2), and reducing equivalents in the form of NADH.
Reaction:The pyruvate dehydrogenase complex catalyzes the oxidative decarboxylation of pyruvate to the acetyl group of acetyl-CoA.This complex requires the sequential action of three different enzymes and five different enzymes and five different coenzymes or prosthetic groups - Thiamine pyrophosphate(TPP), flavin adenine dinucleotide(FAD), coenzyme A(CoA-SH), Nicotinamide adenine dinucleotide(NAD).To learn more about catalysis visit:
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What is the name of the molecule below?
G
O A. Ethyne
O B. Ethene
C. Methene
OD. Methyne
H-C=C-H
The name of the molecule above is Ethene
What are organic compounds?Organic compounds can be defined as compounds containing carbon and hydrogen.
Some classes of organic compounds are:
AlkanesAlkenesAlkanolsAlkanalsAlkynesSo therefore, he name of the molecule above is Ethene
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Explain why all the elements of period 3 is placed on the periodic table in period 3
Answer:
3 Electron shell/orbit
Explanation:
the number of shell an element has is what determines the period of that element.
when in extinguishing agent is determined to be safe and effective for you from combustible Metals it will
Dry powder extinguishers
They are for Class D or combustible metal fires, only. They are ineffective on all other classes of fires.
What is an Extinguishing agent ?Extinguishing Agent means a source of extinguishment in which to quickly and effectively suppress the fire.
They consist of ABC Dry Chemical, BC Dry Chemical, Dry Powder, Water, Foam, Wet Chemical, Halogenated, and Carbon Dioxide. Dry Chemical extinguishers: Dry chemical extinguishers are the most common and available in few types.Learn more about Extinguishing agent here:
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Substances composed of atoms that all have the same number of protons are called:.
The substances composed of atoms that all have the same number of protons are called elements.
What are the names of substances made up of atoms with the same number of protons?
The substances which are made up of atoms with the same numbers of protons are called as element.
An element is a substance with the same number of protons in all of its atoms. Gold is an example of an element. A pure gold bar is made up of only one element, gold.
All matter is composed of substances known as elements, which have distinct chemical and physical properties and cannot be broken down into other substances via ordinary chemical reactions.
Gold, for example, is an element, as is carbon. Only 92 of the 118 elements occur naturally. The remaining elements are unstable because they were only created in laboratories.
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Explain one way that God showed precision in his creation. (use complete sentences)
One way in which God showed precision in his creation was his mighty love on the he has on his creation
The book of John made us to know that: For God do love the world that he gave his only begotten son that whosoever believeth in him shall not perish but have everlasting life.
What is creation?Creations is the art of producing or making something out of something
So therefore, one way in which God showed precision in his creation was his mighty love on the he has on his creation
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At a particular temperature, the solubility of Kr in water is 0.060 M when the partial pressure is 0.90 atm. What partial pressure (in atm) of Kr would give a solubility of 0.150 M
At a particular temperature, the solubility of He in water is 0.060 M when the partial pressure is 0.90 atm. 2.27 atm is the partial pressure of Kr would give a solubility of 0.150 M.
What is Henry's Law ?According to Henry's law, the weight of a gas dissolved by a liquid is proportional to the pressure of the gas onto the liquid.With very few exceptions, a solute molecule in an extremely diluted solution will only have solvent molecules as its close neighbors. This means that the likelihood that a specific solute molecule will escape into the gas phase is predicted to be independent of the total concentration of solute molecules.Solution:
The solubility of gas is directly proportional to partial pressure. It is expressed as:
S = [tex]K_ h \times P _g_a_s[/tex]
where, S = Solubility of gas
[tex]K_h[/tex] = Henry's Law constant
[tex]P_g_a_s[/tex] = Partial pressure of gas
Now, put the values in above expression we get
0.060M = [tex]K_h[/tex] × 0.9 atm
[tex]K_h[/tex] = = 0.066 M/atm
Now we have to find the partial pressure of He
0.150 M = 0.066 M/atm × [tex]P_g_a_s[/tex]
[tex]P_g_a_s[/tex] = 2.27 atm
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This table resembles a condensed version of the modern periodic table. Using the full periodic table as a reference, type the symbols for the elements from part A into this table based on their appropriate group and period.
re write the question.
Explanation:
it seems incomplete.
What is the total pressure of a mixture of he and h2 if the partial pressures are 320 mm hg and 800 mm hg respectively
Answer:
1120 mm Hg
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is glycine mono functional?
Answer:
Yes
Explanation:
Answer:it act as a precursor to proteins
Explanation:
Calculate the number of molecules in 3 mol of carbon dioxide (CO2).
18.06 ₓ [tex]10^{23}[/tex] molecules in 3 mol of carbon dioxide (CO2).
What is Avogadro's number?The proportionality factor that connects the quantity of substance in a sample to the number of constituent particles in that sample is called the Avogadro constant. The reciprocal mole, which is its SI unit, is specified precisely as NA 6.02214076 × [tex]10^{23}[/tex] [tex]mol^{-1}[/tex]. It bears Amedeo Avogadro's name, an Italian scientist.
When dealing with very big quantities, chemistry uses Avogadro's number. It serves as the foundation for the mole, a unit of measurement that makes converting between moles, mass, and the number of molecules simple. The quantity, for instance, can be used to determine how many water molecules make up a single snowflake.
1 Mole is 6.02ₓ [tex]10^{23}[/tex] molecules.
Therefore 3 Moles of Carbon Dioxide ([tex]CO_{2}[/tex]) =3(6.02ₓ [tex]10^{23}[/tex])
3 Moles of Carbon Dioxide ([tex]CO_{2}[/tex]) =18.06 ₓ [tex]10^{23}[/tex]molecules of [tex]CO_{2}[/tex].
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The half-life of cesium-137 is 30 years. Suppose we have a 150 mg sample. (a) Find the mass (in mg) that remains after t years.
The half-life of cesium-137 is 30 years. Suppose we have a 150 mg sample. The masses (in mg) that remains after t years A=150/2^t/30yrs
what do you mean by half-life?A substance's half-life is the amount of time it takes for half of it to decompose.
What is a half-life example?Half-life is the length of time it takes for half of an unstable nucleus to go through its decay process. A radioactive element's half-life decay time varies depending on the element. For instance, carbon-10 has a half-life of only 19 seconds, making it impossible to discover in nature. On the other hand, uranium-233 has a half-life of almost 160000 years.
When n half-lives have passed, the formula for estimating the amount still left is:-
A=A°/2^n
where,
A=initial amount
A°=remaining amount
n=t/t_{1/2}
A=150/2^t/30yrs
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