A sample of iodine-131 has an activity of 200 mCi. If the half-life of iodine-131 is 8. 0 days, what activity is observed after 16 days?


0. 5 half lives


Step [1]: Determine the number of half lives.


x 128


5. 88 x10-37


mci


16 days


128 half lives


2 half lives


80 half lives


1 day


Step [2]: Find the final activity.


50. 0 mci


200. Mci


200. Mci


(initial activity)

Let us take our minds back to the kinetic theory of matter. Recall that the particles that compose matter are in constant random motion and the solids are arranged in a definite pattern while the particles of a gas are in random motion.

As such, the zinc has its atoms in a fixed pattern while the hydrogen atoms are roaming freely in the gaseous state.

Given that;

Amount of the acid = 10.95 g/36.5 g/mol = 0.3 moles

Amount of the zinc = 1g/65 g/mol = 0.015 moles

Given the reaction equation; \(Zn(s) + 2HCl(aq) ------ > ZnCl_{2} (aq) + H_{2}(g)\)

1 mole of Zn reacts with 2 moles of acid

0.015 moles of zinc reacts with x moles of acid

x =0.015 moles * 2 moles / 1 mole

= 0.03 moles

Thus, the zinc is the limiting reactant.

1 moles of the zinc produces 1 mole of the hydrogen

The amount of the hydrogen produced =  0.03 moles * 2 g/mol

= 0.06 moles of hydrogen

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The equilibrium concentration of silver ions in this solution cannot be determined without knowing the rate constants of the reaction between silver and Cu(CH3CO2)2.

The level of concentration of an identifiable chemical species in an environment at equilibrium is known as equilibrium concentration. A different name for it is the constant state percentage. The equilibrium constant is the measurement of the response and the initial amounts of both reactants and byproducts in the system define this level of concentration.

The full name of Cu(CH3CO2)2 compound is dimethyl carbonate cupric complex in aqueous solution.

The response is:

Cu(s) + 2AgCH3CO2(aq) = Cu(s) + Cu(CH3CO2)2(aq) + Ag(s)

Cu(CH3CO2)2 has a molecular weight of 0.0880 moles.

The silver content is 7.0 g/108 g/mol, or 0.0648 moles of silver.

Cu(CH3CO2)2 and Ag have a mole ratio of 1:2, meaning that 0.0880 moles of Cu(CH3CO2)2 will react with 0.1760 moles of Ag.

Because there are fewer moles of Ag than there are of Cu(CH3CO2)2, all of the Cu(CH3CO2)2 will react with whereas some of the Ag will not.

The total amount of Ag that won't undergo any reactions is equal to 0.1112 moles of Ag (0.1760 moles - 0.0648 moles).

The unprocessed Ag weighs 11.9 g, or 0.1112 moles x 108 g/mol.

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Answer:

Earth and its atmosphere are continuously altered. Plate tectonics shift the continents, raise mountains and move the ocean floor while processes not fully understood alter the climate

Explanation:

Based on the data provided, (a) the cubic crystal structure is FCC, (b) the lattice constant in Angstroms is 0.3615 and (c) the unknown element is Nickel.

Here is the solution:

The first peak at 2qA = 11.622558513411379 degrees corresponds to the (111) reflection, which is the most intense reflection for FCC crystals.

The second peak at 2qB = 13.428288268863643 degrees corresponds to the (200) reflection.

The Bragg equation is:

2d sin(θ) = λ

where d is the lattice spacing, θ is the scattering angle, and λ is the wavelength of the X-ray.

Solving for d, we get:

d = λ / 2 sin(θ)

Substituting the values for λ and θ, we get:

d = 0.71144 Å / 2 sin(11.622558513411379°)

≈ 0.3615 Å

The lattice constant for FCC Nickel is 0.3524 Å, which is very close to the calculated value of 0.3615 Å. Therefore, the unknown element is Nickel.

Thus, (a) the cubic crystal structure is FCC, (b) the lattice constant in Angstroms is 0.3615 and (c) the unknown element is Nickel.

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Answer:

to simplify the number by using fewer digits

Explanation:

to simplify the number by using fewer digits

The following information should be considered;

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The ion at the center of a silicon-oxygen tetrahedron is sorrounded by four oxygen ions.

Silicate minerals are built around a molecular ion called the silicon-oxygen tetrahedron. These are generally called the rock-forming minerals. The silicon-oxygen tetrahedron (SiO4) consists of a single silicon atom at the center and four oxygen atoms located at the four corners of the tetrahedron. Each oxygen ion has a -2 charge and the silicon ion has a +4 charge. In the silicon- oxygen  tetrahedron, the silicon ion shares one of its four valence electrons with each of the four oxygen ions in a covalent bond to create a symmetrical geometric four-sided pyramid figure.

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An emulsion is a mixture of two liquids that are not normally soluble in each other, such as oil and water. The liquids are held together by an emulsifying agent, such as lecithin, which acts as a stabilizer.

Using brine can help with an emulsion because the salt in the brine can help to break down the proteins in the emulsifying agent, causing it to bind more strongly with the liquids and improving the stability of the mixture. Additionally, the high salt content in brine can also help to inhibit the growth of bacteria, which can be beneficial when working with perishable ingredients in an emulsion.

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The molar mass of aluminum sulfate is 342.2 g/mol.

The molar mass of aluminium sulfate Al₂(SO₄)₃, will be equal to the sum of the molar masses of all the atoms that make up a mole of this compound.

From (Al₂(SO₄)₃, 1 mole of aluminum sulfate contains;

two moles of aluminum, 2xAl

three moles of sulfur, 3xS

twelve moles of oxygen, 3x4x0

From periodic table, the molar mass of aluminum, sulfur and oxygen is;

Al= 26.981538 g mol⁻¹

S= 32.065 g mol⁻¹

O=14.9994 g mol⁻¹

To find molar mass of aluminum sulfate we need to do

2xMmAl+3xMmS+12XMmO

2X26.981538 g mol⁻¹+3X32.065 g mol⁻¹+12X15.9994 g mol⁻¹

This will give  Mm Al₂(SO₄)₃  = 342.150876 g mol⁻¹

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Answer:-Science have researched more facts and cool things about it-It would have more facts and things to learn-The quality would be better and more understandingI just tried 3 quick ideas I hope it can help a bit

Explanation:

Answer:

the answer is you should know this already :)))))))))))))))))))))))))))))))))))))))))))))))))))

Answer:977.34

Explanation:

divide 2551 and 273 to get 3.778. then multiply 3.78 by 273 to gry 977.34.

Answer:

I think air is more denser than oxygen

Give names to equations 1, 2, and 3.Equation 3.2 N2O (g) N2 (g) + 0.5 O2 (g) H = -81.6 kJEquation 2: NO (g) + 1/2 O2 (g) + (1/2) NO2 (g) = +56.55 kJ

Equation 1 states that N2 (g), O2 (g), 2NO (g), and H = +180.7 kJ.

See Equation of state for cosmological applications of this (cosmology). See Optimum control General technique for further information on how this idea is used in optimal control theory.An equation of state is a thermodynamic formula used in physics, chemistry, andthermodynamics to describe the state of matter under a particular set of physical parameters, such as pressure, volume, temperature, or internal energy.[1] The Helmholtz free energy is used to formulate the majority of current equations of state. The characteristics of pure substances and mixtures in their liquid, gaseous, and solid forms as well as the state of matter

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Equilibrium is a state in a chemical reaction where the rate of the forward reaction is equal to the rate of the reverse reaction, resulting in no net change in the concentrations of reactants and products. It is represented by a double arrow (⇌) in chemical equations. In the given equation: H₂O (g) + CO (g) ⇌ H₂(g) + CO₂(g) + 42 KJ

To shift the equilibrium to the right, one or more of the following could occur:

Increasing the concentration of H₂ or CO₂

Decreasing the concentration of H₂O or CO

Increasing the pressure

Removing some of the products (H₂ and CO₂)

Decreasing the temperature

To shift the equilibrium to the left, one or more of the following could occur:

Decreasing the concentration of H₂ or CO₂

Decreasing the pressure

Increasing the temperature

If pressure is increased, the equilibrium will shift in the direction that produces fewer moles of gas. In this case, since there are fewer moles of gas on the right side of the equation (H₂ and CO₂), the equilibrium will shift to the right. If heat is added, the equilibrium will shift in the endothermic direction to absorb the additional heat. In this case, the forward reaction is endothermic (42 KJ on the right side), so the equilibrium will shift to the right to consume the added heat.

If CO is added, the equilibrium will shift to the right to consume the additional CO.The concentration of H₂O and CO₂ will increase, while the concentrations of H₂ and CO will decrease until a new equilibrium is reached.

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Answer:

Empirical formula = NO₂

Molecular formula = N₂O₄

Explanation:

Percentage mass of Nitrogen = 30.4 %

Percentage mass of Oxygen = 60.9 %

Mole ratio of the elements:

Nitrogen = 30.4/14 = 2.17

Oxygen = 69.9/16 = 4.37

Dividing by the smallest ratio to obtain a simple ratio

Nitrogen: 2.17/2.17 = 1

Oxygen; 4.37/2.17 = 2

Therefore, the simplest mole ratio is 1:2

Empirical formula = NO₂

Molecular formula = n(empirical formula), therefore, molecular mass = n *(empirical mass)

92.010 = n(14 + 32)

92.010 = 46n

n = 92.010/46

n = 2

Therefore, molecular formula = 2(NO₂)

Molecular formula = N₂O₄

Increasing ocean acidification has been attributed to. a. ocean absorption of excess atmospheric carbon dioxide.

In the field of biology, ocean acidification can be described as a process in which the acid quantity in the ocean increases due to an increase in the amount of carbon dioxide in the ocean.

When excess carbon dioxide is absorbed by the ocean from the atmosphere, then this carbon dioxide serves as a reacting agent for acidic compounds.

When the acid amounts in the ocean are increased then this can result in the death of living organisms in the oceans as they cannot survive in acidic environments.

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Use of a more polar eluent can impact the separation and elution behavior of compounds in chromatography, favoring polar compounds and potentially affecting the resolution and selectivity of the analysis.

If only the more polar eluent was used in the experiment, several outcomes could be expected:

Increased Solubility: The more polar eluent would have higher solubility for polar compounds, enhancing their dissolution and movement through the chromatographic system. This would result in faster elution of polar compounds and potentially better separation between different components in the sample.

Reduced Retention: The more polar eluent would have a stronger interaction with the stationary phase, leading to decreased retention time for non-polar or weakly polar compounds. This could cause these compounds to elute quickly without adequate separation, resulting in poor resolution of the target analytes.

Decreased Selectivity: Since the more polar eluent has a greater affinity for polar compounds, it might not efficiently separate compounds with similar polarities. This could lead to co-elution of compounds or insufficient separation between closely related analytes.

Elution Order Changes: In some cases, the more polar eluent could cause a reversal in the elution order of compounds compared to a less polar eluent. This means that compounds that previously eluted early might now elute later and vice versa, altering the overall chromatographic profile.

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The amount of energy required to heat the 37.0 g chunk of copper from 14.1 °C to 100.0 °C is approximately 1.214 kJ

To calculate the amount of energy required to heat the copper, we use the formula:

Energy = mass * specific heat capacity * change in temperature

Given:

Mass of copper = 37.0 g

Specific heat capacity of copper = 0.385 J/g °C

Change in temperature = (100.0 °C - 14.1 °C) = 85.9 °C

Plugging the values into the formula:

Energy = 37.0 g * 0.385 J/g °C * 85.9 °C

Calculating the result:

Energy = 1214.055 J

To convert the energy from joules to kilojoules, we divide by 1000:

Energy = 1214.055 J / 1000 = 1.214055 kJ

Therefore, the amount of energy required to heat the 37.0 g chunk of copper from 14.1 °C to 100.0 °C is approximately 1.214055 kJ

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Answer:

Calendar and periodic table both have repetitive patterns.

Explanation:

In calendar the days are arranged and divided into weeks whereas in the periodic table the elements are arranged in increasing atomic number and divided into groups

Answer:

D

Explanation:

electrons have a negative charge. gaining electrons increases the negative charge.

Metallic solids,

the atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties. All exhibit high thermal and electrical conductivity, metallic luster, and malleability.

Answer: c. metallic

Answer:

This is what we're given:

P (pressure), which is 1.95 atm

V(volume), which is 11.30 L.

n(number of moles), which is 0.554 moles of helium gas.

We have to find T, or temperature. To do this, we'll need to use the Ideal Gas Law, which is:

\(PV = nRT\)

Rearranging this equation to get temperature on one side, we get:\\ \(T =\frac{PV}{nR}\\ \\

Pressure \: is \: in \: atm \: and \\ volume \: is \: in \: L . \: This \: tells \\ \: us \: that \: we'll \: need \: to \: \\ use \: the \: value \: of \: 0.08206 L atm/K \: mol \: for \: R \: the \: ideal \: gas \: constant.\\ \\ Plugging in all of the values, we can solve for temperature:

\(T =\frac{PV}{nR}\\ \\

T = (1.95 atm × 12.30 L) ÷

(0.654 mol × 0.0820575LatmK−1)

mol

\(T =\frac{PV}{nR} \\ \\

T =

\frac{ (1.95 atm × 12.30 L)}{(0.654 mol × 0.0820575LatmK−1)} \)

\(T = 447 K \)

Boyle’s Law (PV law)

a. Volume of a GIVEN MASS OF GAS (mass is fixed) is inversely proportional to the Absolute pressure of the gas at constant Temperature.

b. Absolute pressure means pressure that is measured relative to Vacuum. Vacuum = 0 pressure. Thus, absolute pressure is measured relative to absolute 0.

c. Another way : PV = Constant. Thus, if you measure the Pressure and Volume at 3 different times, then P1 V1 = P2 V2 = P3 V3. In order to keep the product as a constant, whenever Pressure increases, the Volume will decrease.

Charle’s Law (VT Law)

a. Volume of a GIVEN MASS OF GAS (mass is fixed) is directly proportional to the Absolute Temperature at constant pressure.

b. When you measure the Temperature of a body on a scale in which 0 corresponds to Absolute 0, then the measured temperature is Absolute Temperature. Put simply, this refers to the Kelvin scale.

c. Absolute 0 is the temperature at which objects are at their lowest possible energy (Since Temperature is a measurement of the Kinetic energy of the atoms).

Gay Lussac Law (PT Law)

a. Pressure of a GIVEN AMOUNT OF MASS (mass is fixed) at constant volume is directly proportional to the absolute Temperature (that is, Kelvin Temperature).

b. Another way : P / T = Constant. P1 / T1 = P2 / T2 = P3 / T3.

Avogadro’s law (Vn law)

a. All the above laws were talking about relationships at fixed mass. So we needed a law which would relate mass with other quantities. This is Avogadro’s law.

b. It is a very straight forward law, if the amount of gas in a Container increases (that is, if the amount of matter increases), then the Volume of the gas increases which is very straight forward.

c. Volume is directly proportional to n (number of moles) or V/n = Constant.

Considering the Ideal Gas Law, at 485.05 °K 0.554 moles of helium gas will occupy 11.30 liters at 1.95 atmospheres.

On the other side, the 4 gas laws are Gay Lussac's law, Boyle's law, Charles' Law and Avogadro's law.

Ideal gases are a simplification of real gases that is done to study them more easily. It is considered to be formed by point particles, do not interact with each other and move randomly. It is also considered that the molecules of an ideal gas, in themselves, do not occupy any volume.

The pressure, P, the temperature, T, and the volume, V, of an ideal gas, are related by a simple formula called the ideal gas law:

P×V = n×R×T

where:

In this case, you know:

Replacing in the Ideal Gas Law:

1.95 atm×11.30 L = 0.554 moles× 0.082 \(\frac{atm L}{mol K}\)× T

Solving:

T= (1.95 atm×11.30 L) ÷ (0.554 moles× 0.082 \(\frac{atm L}{mol K}\))  

T= 485.05 K

Finally, at 485.05 °K 0.554 moles of helium gas will occupy 11.30 liters at 1.95 atmospheres.

Gay Lussac's law states that the pressure of the gas is directly proportional to its temperature: when there is a constant volume, as the temperature increases, the pressure of the gas increases. And when the temperature is decreased, gas pressure decreases.

Boyle's law says that volume is inversely proportional to pressure: if pressure increases, volume decreases; while if the pressure decreases, the volume increases.

Charles' Law that the volume is directly proportional to the temperature of the gas: if the temperature increases, the volume of the gas increases; while if the temperature of the gas decreases, the volume decreases.

Avogadro's law states that the volume is directly proportional to the amount of gas: if the amount of gas increases, the volume will increase, while if the amount of gas decreases, the volume will decrease.

In summary, the 4 gas laws are Gay Lussac's law, Boyle's law, Charles' Law and Avogadro's law.

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In this way, the molecule possesses six chiral centers. Each of the six carbon atoms has four distinct groups bonded to it.

A molecule is the tiniest unit of any substance that is capable of independent existence and that is made up of one or more components while still maintaining the substance's physical and chemical properties. Even more atoms can be separated from molecules. As an illustration, the oxygen molecule is denoted by the symbol O, and the oxygen atom by the symbol O.

A molecule is made up of two or more atoms and is the smallest unit that can be used to identify the pure substance while retaining its chemical composition and physical properties.

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The pKa value of formic acid is approximately 3.75. pKa is a measure of the acidity or basicity of a compound and represents the negative logarithm of the acid dissociation constant (Ka).

Formic acid, also known as methanoic acid, is a weak acid commonly found in nature. It is produced by various organisms, including ants, hence the name "formic" derived from the Latin word for ant, formica.

The pKa value of formic acid indicates that it is a moderately strong acid. In aqueous solutions, formic acid partially dissociates into hydrogen ions (H⁺) and formate ions (HCOO⁻). This pKa value is important in determining the acid strength and reactivity of formic acid in various chemical reactions and its behavior in different environments.

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Answer:

static friction: books on a desk and a parked car

kinetic friction: moving furniture and riding a bike

fluid friction: swimming and skydiving

Explanation:

Answer:

static friction:

kinetic friction:

fluid friction:

The reactant \(O_{2}\) is limiting if we begin with 9. 50 grams of al and 9. 50 grams of  \(O_{2}\)   .

The reactant whose number of moles is present in less quantity is called limiting reactant .

Calculation,

Given mass of Aluminium and oxygen

Mass of Aluminium = 9. 50 grams

and Mass of oxygen = 9. 50 grams

Number of moles of aluminium = given mass / molar mass of aluminium

Number of moles of aluminium = 9. 50 grams/ 26.99 = 0.351 mole

Number of moles of oxygen = given mass / molar mass of oxygen

Number of moles of oxygen = 9. 50 grams/ 31.999  = 0.296 mole

The reactant \(O_{2}\) is limiting because oxygen present in less quantity or in limiting quantity and consume rapidly.

Therefor , the reactant \(O_{2}\) is limiting if we begin with 9. 50 grams of al and 9. 50 grams of  \(O_{2}\)   .

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The correct option is C, It is an elimination reaction involving the loss of a halogen leaving group and hydrogen from adjacent carbons this is a correct description of a dehydrohalogenation reaction.

An elimination reaction is a type of chemical reaction where a molecule loses atoms or groups of atoms from its structure to form a new molecule. In an elimination reaction, a molecule is converted into a product by the removal of a small molecule such as water, ammonia or hydrogen halide from two adjacent atoms in the molecule. The reaction generally occurs between a substrate molecule and a nucleophile or base molecule.

Elimination reactions are important in organic chemistry as they play a crucial role in the synthesis of complex molecules. They are widely used in industries such as the pharmaceutical industry, where they are used to make drugs and other chemical compounds. Additionally, elimination reactions are also essential in biological processes, such as the metabolism of drugs in the human body.

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Complete Question:

which of the following is a correct description of a dehydrohalogenation reaction?

multiple choice questions.

A). it is an addition reaction involving the formation of new bonds to a halogen and hydrogen on adjacent carbons.

B). it is an addition reaction involving the formation of new bonds to both a halogen and hydrogen on the same carbon.

C). it is an elimination reaction involving the loss of a halogen leaving group and a hydrogen from adjacent carbons.

D). it is an elimination reaction involving the loss of both a halogen leaving group and a hydrogen from the same carbon.