In an experiment, a student gently heated a hydrated copper compound to remove the water of hydration. The following data was recorded:
Mass of crucible, cover, and contents before heating = 23.4 g.
Mass of empty crucible and cover = 18.82 g.
Mass of crucible, cover, and contents after heating to constant mass = 20.94 g.

Answer:

i believe its called A. periods

The average wavelength of the fluorine molecule will be 2.36 × 10⁻¹¹ metres.

Fluorine Molecule's Speed = 442.4 m/s

The Molar Mass of the F₂ = 38 g/mol

Now as we know that any molecule's

1 mole contain  = 6.022 × 10²³ Molecule

So, 1 Fluorine molecule mass =

Fluorine's Molar mass / Number of Fluorine molecule in 1 mole

So, 1 Fluorine molecule mass = 38 / ( 6.022 × 10²³ )

1 Fluorine molecule mass = 6.31 × 10⁻²³ g

1 Fluorine molecule mass = 6.31 × 10⁻²⁶  Kg

So molecule's momentum = Molecule's mass × Molecule's Velocity

So molecule's momentum = ( 6.31 × 10⁻²⁶ ) × 442.4

So molecule's momentum = 2.8 × 10⁻²³  Kg.m/s

Now wavelength of Fluorine molecule = λ = planks constant / momentum

wavelength of Fluorine molecule = λ = ( 6.626 × 10⁻³⁴ ) / ( 2.8 × 10⁻²³ )

wavelength of Fluorine molecule = λ = 2.36 × 10⁻¹¹ metre

So the wavelength of the diatomic fluorine molecule came out to be 2.36 × 10⁻¹¹ metres after applying all the concepts and formulas.

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Answer:

B. An astronaut in a spaceship

Isolated system :-

In an isolated system, there is no transfer of energy or matter between the system and the environment.

Hope it helps!

The pH of a 0.64 M solution of pyridine (C₅H₅N) is 9.52.  

A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.

The equation for the protonation of the base pyridine is the following:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻   (1)

Kb = 1.7 × 10⁻⁹ (Given)

To calculate the pH of the solution we need to use the following equation:

pH + pOH = 14

pH = 14 - pOH

     =14 - [-log[OH⁻]]

    = 14 + log[OH⁻]

Now, we need to find the concentration of the OH⁻ ions. Since pyridine is a weak base, at the equilibrium we have (eq 1):

C₅H₅N  +  H₂O  ⇄  C₅H₅NH⁺  +  OH⁻

0.64 - x                          x              x

After entering the values of [C₅H₅N] = 0.64-x, [C₅H₅NH⁺] = x, and [OH⁻] = x, into equation (2) we can find the concentration of OH⁻:

1.7 × 10⁻⁹  =[C₅H₅NH⁺]  [OH⁻]  /  [C₅H₅N]

                = x . x / 0.64-x

1.7 × 10⁻⁹ (0.64-x) - x² = 0

Solving the above quadratic equation for x, we have :

Now, We can calculate the pH, after taking the positive value, x₂, (concentrations cannot be negative) and entering into above equation :

pH = 14 + log[OH⁻]

     = 14 + log (3.32 x 10⁻⁵)

     = 9.52

Therefore, the pH of the solution of pyridine is 9.52.

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Answer:245.088

Explanation: you subtract final temperature with initial temperature = 46 then multiply by grams = 552 then multiplied by J = 245.088

1.199 M is the concentration of KCI in the resulting solution.

A mole is defined as 6.02214076 × [tex]10^{23}[/tex] of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.

No.of moles of KCI

[tex]Moles = \frac{mass}{molar \;mass}[/tex]

[tex]Moles = \frac{44.7 g}{74.5513 g/mol}[/tex]

= 0.599 moles

Vol.of the solution,V= 500 ml

= 0.5 liter

Molarity

[tex]Molality = \frac{Moles \;solute}{Volume \;of \;solution \;in \;litre}[/tex]

[tex]Molality = \frac{0.599 moles}{0.5 liter}[/tex]

= 1.199 M

Hence, 1.199 M is the concentration of KCI in the resulting solution.

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The standard enthalpy change associated with the given reaction at 25 °C using the following enthalpies of formation will be − 902.4 kJ

The standard enthalpy change of formation of a compound is the enthalpy change which occurs when one mole of the compound is formed from its elements under standard conditions, and with everything in its standard state.

According to the balanced chemical equation ;

CH₄(g) + 2O₂(g) ⟶ CO₂(g) + 2H₂O(l)

Now,

ΔH⁰ = ΔH⁰f(products) − ΔH⁰f(reactants)

​

       = [ΔH⁰(CO₂) +ΔH⁰(H₂O)] − [ΔH⁰(CH₄) + 2ΔH⁰(O₂)]

       = [−393.5 + 2 x (−285.8)] − [−62.7 + 2 x 0]

        = − 902.4 kJ

Hence, The standard enthalpy change associated with the given reaction at 25 °C using the following enthalpies of formation will be − 902.4 kJ

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In terms of the disappearance of the reactants, the rate equations are R= -kd[I-]/dt and  -kd[OCl-]/dt.

The term ionic reaction refers to the reaction that takes place between two ions. In this case, the ionic reaction is; I-(aq) + OCl-(aq) -------> Cl-(aq) + OI-(aq).

The rate equations in terms of the disappearance of the reactants is;

R= -kd[I-]/dt

And

R = -kd[OCl-]/dt

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The molar mass of the unknown gas is determined as 17.75 g.

The rate of gas diffusion is given by Graham's law.

R₁√M₁ = R₂√M₂

where;

[tex]\frac{R_1}{R_2} = \sqrt{\frac{M_2}{M_1} } \\\\\frac{2R_2}{R_2} = \sqrt{\frac{71}{M_1} }\\\\2 = \sqrt{\frac{71}{M_1} }\\\\2^2 = \frac{71}{M_1} \\\\M_1 = \frac{71}{4} \\\\M_1 = 17.75 \ g[/tex]

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A voltaic cell is used to produce electrical energy with the help of chemical reactions.

Relating to, or producing direct electric current by chemical action.

A Voltaic Cell (also known as a Galvanic Cell) is an electrochemical cell that uses spontaneous redox reactions to generate electricity. It consists of two separate half-cells.

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The exact mass of one Na - atom is 22.98977 amu and thus, the weight of two sodium atoms in present in Na₂C₆H₆O₇ is 45.979539 g/mol.

The molar mass of a substance is the mass in grams of 1 mole of the substance.

We can obtain a substance's molar mass by summing the molar masses of its component atoms.

Mass of one Na atom = 22.98977

Mass of two Na atom = 22.98977 x 2

                                      = 45.97954

                                       = 45.9 (up to 3 Significant figures)

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Answer: .75 M

Explanation:

Explanation:

it applies to pressure laws

0.3 L is the final volume when M₁ = 3 M, V₁ = 0.125L, M₂ = 1.25M.

The amount of space occupied by a three-dimensional figure as measured in cubic units.

Given data:

M₁ = 3 M

V₁ = 0.125L

M₂ = 1.25M

V₂ = ?

Solution:

M₁V₁ = M₂V₂

3 M × 0.125L = 1.25M × V₂

V₂ = 0.3 L

Hence, 0.3 L is the final volume.

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Answer:

A

Explanation:

Due to the presence of three unpaired electrons, phosphorus is paramagnetic.

Electronic configuration of Phosphorus:-

[Ne] 3S2  3P3

By looking at a substance's electron configuration, one can identify whether or not it has magnetic qualities. If a substance has unpaired electrons, it is paramagnetic; if all of its electrons are paired, it is diamagnetic.

A tiny, positive susceptibility to magnetic fields exists in materials. When exposed to a magnetic field, these materials are only weakly drawn to it; once the external field is removed, they lose their magnetic qualities.

A weak, negative sensitivity to magnetic fields exists in materials. When exposed to a magnetic field, diamagnetic materials are partially repulsed and lose their magnetic properties when the external field is removed.

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Answer:

6.022 x 10²³

Explanation:

The number of atoms =  the number of moles x with the Avogadro's number.

(The Avogadro's number is 6.022 x 10²³ atoms / moles)

number of atoms = 1.00 moles x 6.022 x 10²³ atoms / mole

number of atoms =  6.022 x 10²³ atoms

(There is no need to simplify?) = 6.022 x 10²³

(ps. This is my first time doing this question so im sorry if i got it wrong

(つ﹏⊂)

Answer:31,631.04

Explanation: multiply final temp with initial temp = 42 then multiplied by grams = 7,560 then multiplied by J = 31,631.04

To ensure data traceability and accessibility is to complete a study beginning-to-end on a closed system or platform.

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In an endothermic reaction, Keq increases as the temperature increases and vice versa.

In an exothermic reaction, Keq decreases as the temperature increases and vice versa.

Therefore, the temperature is the only factor that affects the equilibrium constant of a reaction.

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Answer:

0.004136 moles

Explanation:

From our question we have been asked to determine the quantity in moles of silver atoms having 2.49 × 10²¹ atoms of silver.

We know that from Avogadro's constant, one mole of silver contains 6.02 x 10²³ atoms.

Thus,

1 mole of silver contains 6.02 x 10²³ atoms.

x moles of silver contains 2.49 × 10²¹ atoms

Cross multiply to obtain the number of moles of silver,

x moles = (2.49 × 10²¹ x 1)/(6.02 x 10²³)

= 0.004136 moles

Therefore the quantity of silver in moles is 0.004136 moles

If the balloon had a volume of 3 L at a depth of 50 m, the original volume of the balloon will be

Significant figures are the number of digits in a value, often a measurement, that contribute to the degree of accuracy of the value.

The pressure at a depth of 40 m is the hydrostatic pressure of the water plus the atmospheric pressure.

The hydrostatic pressure P of a liquid is given by the formula ;

P = ρgh

where,

P =  1000 kg m⁻³ x 9.81 ms⁻² x 50 m

   = 1000 kg m⁻¹ x 9.81 s⁻² x 50

   = 4.9 x 10⁵ Pa

Lets's Convert Pa in to atm

    =   4.9 x 10⁵ Pa x 1 / 103. 325 x 10³ Pa

    = 4.7 atm

Mow, lets calculate P(atm) ;

P(atm) = 14.7 psi x 1 atm / 14.7 psi

          = 1 atm

Total Pressure at 50 m is ;

P(total) = 4.7 atm + 1 atm

            = 5.7 atm

Now we can apply Boyle's Law to calculate the volume of the balloon at the surface.

P₁V₁ = P₂V₂

V₂ = P₁V₁ / P₂

According to the question ;

V₂ = 3 L x 5.7 atm  / 1 atm

     = 17.1 L

     = 20 L ( 1 significant figure)

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A complete ionic equation shows ions formed from each of the species. It also show the charge on each of the ions.It also shows all reactants as compounds or elements. The ions formed and their charges can only be inferred from this equation.

The net ionic equation shows  the chemical species involve in chemical reaction while the complete ionic equation also involve the spectator ions.

These ions are same in both side of chemical reaction and thus cancels out each other.

Their presence can not effect the equilibrium of reaction that's why these ions are omitted in net ionic equation.  

The net ionic equation state that whether precipitation is occur or not.

If the chemical reaction have no net ionic equation it means all are in aqueous from not precipitation occur.

Balanced Chemical equation:

HClO₂(aq) + NaOH(aq) → H₂O(l) + NaClO₂ (aq)

Ionic equation:

H⁺(aq) + ClO₂⁻(aq) + Na⁺(aq) + OH⁻(aq) → H₂O(l) + Na⁺(aq) + ClO₂⁻ (aq)

Net ionic equation:

H⁺(aq) + OH⁻(aq) → H₂O(l)  

The ClO₂⁻(aq) and Na⁺ (aq) are spectator ions that's why these are not written in net ionic equation.

The water can not be splitted into ions because it is present in liquid form.

Hence, The net ionic equation shows  the chemical species involve in chemical reaction while the complete ionic equation also involve the spectator ions.

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The empirical formula would be  [tex]C_2H_3O_2[/tex] and the molecular formula would be  [tex]C_4 H_6 O_4[/tex]

From the illustration:

C = 40.6 g                   H = 5.1 g                      O = 54.2 g

Divide each element by its molar weight:

C = 40.6/12 = 3.4                    H = 5.1/1 = 5.1                  O = 54.2/16 = 3.4

Divide by the smallest:

C = 3.4/3.4 = 1                        H = 5.1/3.4 = 1.5                 O = 3.4/3.4 = 1

Thus, the empirical formula is [tex]C_2H_3O_2[/tex]

To find the molecular formula:

[ [tex]C_2H_3O_2[/tex]]n = molecular formula

where n = molar mass/empirical formula mass

Empirical formula mass = 24 + 3 + 32 = 59

n = 118.084/59 = 2

Thus, the molecular formula is [tex]C_4 H_6 O_4[/tex] which is more or less the same as the empirical formula.

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The Empirical formula will be C₂H₃O₂  and the Molecular formula would be  C₄H₆O₄

Empirical formula is a formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms.

Molecular formula is a chemical formula that gives the total number of atoms of each element in each molecule of a substance.

Given ;

Divide each element by its molar weight:

Divide by the smallest Value:

Thus, the Empirical formula is C₂H₃O₂

Now, to find the molecular formula ;

[C₂H₃O₂ ]n = molecular formula

where n = molar mass / empirical formula mass

Empirical formula mass = 24 + 3 + 32 = 59

n = 118.084 / 59 = 2

[C₂H₃O₂ ]n = molecular formula

[C₂H₃O₂ ]2 = C₄H₆O₄

Thus, the Molecular formula is C₂H₃O₂

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The Sun is presently at a low level of sunspot activity. Hence, option C is correct.

Solar radiation is often called the solar resource for the electromagnetic radiation emitted by the sun.

The Sun is presently at a low level of sunspot activity is the correct answer.

Hence, option C is correct.

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Answer:

The answer is C

The length measurements in increasing order of magnitude from smallest to largest is Nanometer, micrometer, centimeter, decimeter, dekameter, kilometer.

Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events.

Measurement is a process of determining how large or small a physical quantity is as compared to a basic reference quantity of the same kind.

Hence, Among the given length measurements, The increasing order of magnitude from smallest to largest is Nanometer, micrometer, centimeter, decimeter, dekameter, kilometer.

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Question 1

1) The formula of iron(II) iodide is [tex]\text{FeI}_{2}[/tex] and has a formula mass of 309.654 g/mol. This means that in 12.2 grams, there are

So, the molarity is (0.039398812868557)/(0.5) = 0.0788 M (to 3 sf)

2) In 0.039398812868557 mol of iron(II) iodide, there are 0.039398812868557 moles of iron(II) iodide cations, and thus the molarity is still 0.0788 M (to 3 sf)

3) In 0.039398812868557 mol of iron(II) iodide, there are

Thus, the molarity is (0.078797625737114)/(0.5) = 0.158 M (to 3 sf)

Question 2

1) The formula of iron(III) sulfate is [tex]\text{Fe}_{2}\text{(SO}_{4})_{3}[/tex] and has a formula mass of 399.9 g/mol. This means that in 16.8 grams, there are

So, the molarity is (0.042010502625656)/(0.25) = 0.168 M (to 3 sf)

2) In 0.042010502625656 moles of iron(III) sulfate, there are 2(0.042010502625656)=0.084021005251312 moles of iron(III) cations, so the molarity is:

3) In 0.042010502625656 moles of iron(III) sulfate, there are 3(0.042010502625656)=0.12603150787697 moles of sulfate anions, so the molarity is:

Question 3

Since we need 50.0 mL of solution at 0.271 M,

So, we need this from 12.0 M HBr so, meaning that: