Which changes involve forming or breaking chemical bonds?

burning and digesting

boiling and melting

burning and melting

rusting and cutting

Answer: 4.2

Explanation:

[tex]M_{A}V_{A}=M_{B}V_{B}\\(12)V_{A}=(250)(0.20)\\V_{A}=\frac{(250)(0.20)}{12}=\boxed{4.2}[/tex]

The pressure of the compressed tank that was initially filled with hydrogen gas and has a pressure of 100kPa is pressure in the 250mL tank increases.

Boyle's law states that the observation that the pressure of an ideal gas is inversely proportional to its volume at constant temperature.

According to this question, a 1 L compressed tank is filled with hydrogen gas and has a pressure of 100kPa.

If all of the hydrogen gas is removed from the tank and pumped into a 250mL tank, which is smaller in volume, the pressure in the 250mL tank increases.

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Each star on the map represents location of an epicenter. Thus, the correct answer is Option A.

Epicenter is defined as the point directly at the position on the Earth's surface, where the earthquake started. These are represented by the stars on the map.

Scientists use triangulation to find the epicenter of an earthquake.

When seismic data is collected from at least three different locations, it can be used to determine the epicenter by where it intersects.

Every earthquake is recorded on numerous seismographs located in different directions.

Thus, the correct answer is Option A.

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Answer: C. location of a seismograph

Explanation:

The study of matter and energy best describes physical science. Hence, option B is correct.

Physical science is the study of the inorganic world.

Physics is a branch of science that studies matter and its motion through space and time, along with related concepts such as energy and force. Physics is one of the "fundamental sciences" because of the other natural sciences (like biology, geology etc.)

Thus the study of matter and energy best describes physical science. Hence, option B is correct.

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1mol H_2O requires 44kJ heat

Moles of water

Heat required

As per the reaction given

Moles of H_2O=1

Moles of water in 9g

∆H

The solubility of Ca(OH)2 in a 0.469M CaCl2 solution at 31°C, at given Ksp of Ca(OH)2 is determined as 1.626 mM.

The dissociation reaction of Ca(OH)2 is given as follows;

Ca(OH)₂  ⇄ Ca²⁺  + 2OH⁻¹

                     x           2x

Concentration of Ca²⁺ = 0.469 M

Ksp = [x][2x]²

ksp = (0.469)(2x²)

ksp = 4(0.469)x²

ksp = 1.876x²

4.96 x 10⁻⁶ = 1.876x²

x² = (4.96 x 10⁻⁶)/(1.876)

x² = 2.643 x 10⁻⁶

x = √(2.643 x 10⁻⁶)

x = 1.626 x 10⁻³ M

x = 1.626 mM

Thus, the solubility of Ca(OH)2 in a 0.469M CaCl2 solution at 31°C, at given Ksp of Ca(OH)2 is determined as 1.626 mM.

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Equilibrium will shift towards the products when temperature is decreased in an exothermic reaction of the  formation of ammonia.

An exothermic reaction is a reaction in which heat content of the reactants is greater than the heat content of product.

In an exothermic reaction, heat is given off.

For an exothermic reaction in equilibrium, increasing temperature shifts equilibrium to the towards the left, towards the reactants.

On the other, equilibrium will shift towards the products when temperature is decreased.

Therefore, equilibrium will shift towards the products when temperature is decreased in the reaction of the  formation of ammonia.

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345678990098765435779999999999999999995699999

Answer:

The molecular weight 62,03 g/mol

Answer:

hope this helped :( got this from my friend a long time ago but still not sure if it's really correct this

Answer:

ionic bonds

Explanation:

ionic bonds result from the mutual attraction between oppositely charged ions. They tend to be stronger than covalent bonds due to the coulombic attraction between ions of opposite charges.

The pH of a solution that contains 0.0011 moles of KOH in 393 mL of solution is 2.56. Details about pH can be found below.

The pH of a solution can be calculated using the following expression:

pH = - log [H3O+]

However, the hydrogen concentration of the KOH solution can be calculated as follows:

concentration = 0.0011 mol ÷ 0.393 L

concentration = 2.798 × 10-³M

The pH of KOH = - log [2.798 × 10-³M]

pH = 2.56

Therefore, the pH of a solution that contains 0.0011 moles of KOH in 393 mL of solution is 2.56.

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Answer:

About energy transfers:

Explanation:

When there is an energy transfer energy is neither created, nor destroyed. This means when that when one energy store decreases, one or more others must increase.

The weak base ionization constant (Kb) for [tex]CH_3NH_2[/tex] is equal to

[tex]Kb = [CH_3NH^{3+}] [OH^-] / [CH_3NH_2][/tex]

Kb is the base dissociation constant.

The expression for the equilibrium constant, Kb is simply the ratio of the concentration of the products raised to their coefficient to the concentration of the reactants raised to their coefficient.

[tex]CH_3NH_2(aq) + H_2O(l)[/tex]  → [tex]CH_3NH^{3+}(aq) + OH^- (aq)[/tex]

Thus, the expression for the equilibrium constant, Kb fo the above reaction can be written as follow:

[tex]Kb = [CH_3NH^{3+}] [OH^-] / [CH_3NH_2][/tex]

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Volume=1600cm³=1.6dm³=1.6L

Temperature=25°C=273+25=298K

Pressure=75000Pa

Now

Apply ideal gas equation

The number of moles needed is

n=48.43mol.

Calculations

Given the values of the volume and temperature, we would convert them to the required units.

Volume=1600cm³=1.6dm³=1.6L

Temperature=25°C=273+25=298K

Pressure=75000Pa

We would use the ideal gas equation

PV=nRT

n=PV/RT

n=75000(1.6)/8.314(298)

n=48.43mol

Answer:

Hope this helps kinda got confused mid way

Explanation:

So the hydrogen sulphide is H2S for the molecular formula. Then the mass of hydrogen sulphide would be 1×2+32= 34g/mol At STP.

The objects that could hit the atoms in the model shown are neutrons.

A chain reaction is a reaction that is able to sustain itself. In this case, when the neutrons collide with the fissile nucleus, more neutrons are produced which collides with more fissile nuclei thereby sustaining the reaction.

Thus, the objects that could hit the atoms in the model shown are neutrons.

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Answer:

4 moles

Explanation:

For every mole of deuteriomethane consumed, 4 moles of water are produced.

So, the answer is 4 moles.

The number of moles of Cr deposited by 1.5 F of electricity is 0.5 moles

The term electrolysis has to do with thee deposition of a solid when a direct current is passed through its solution.

Given the reaction;  Cr3+(aq)  + 3e ––›Cr(s)

If 3F of electricity is required to deposit  1 mole of Cr

1.5F of electricity is required to deposit  1.5F * 1 mole/3F

= 0.5 moles

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see the attached file!!!

The overall order of the reaction is 3 and the rate law for the reaction is rate =  [A]^n [B]^m [C]^l

1) The order of reactant A is first order reactant because a first-order reaction can be defined as a chemical reaction in which the reaction rate is linearly dependent on the concentration of only one reactant.

The order of reactant B is second order reactant because a second order reaction is a type of chemical reaction that depends on the concentrations of one-second order reactant or two first-order reactants.

Thus, the overall order of the reaction is 3.

2) The rate law in this reaction is;

rate =  [A]^n [B]^m [C]^l

But in this question, since the reactant C is zero order, then it will be simplified to; rate = k[A][B]² .

3) When we plug in the initial concentrations of A and B, we will get the rate constant of the problem which is k = 20.

4) The initial rate when [A]0=4.87 mmol⋅L−1 , [B]0=0.184 mmol⋅L−1 , and [C]0=12.0 mmol⋅L−1 is;

Rate = 20 * 4.87 * 0.184²

Rate = 3.3

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Answer:

See below

Explanation:

9.045/8.492 * 100% = 106.5%

There was other solids already dissolved in the water, or dust or other contaminants got into the water. ....or the measurement was incorrect. (like maybe the solid was still wet?)

Answer:

dfgdsgdffgfddffg

Explanation:

dfggffgdgdf

The reaction is given by

[tex]\\ \rm\Rrightarrow {}^{127}_{56}Ba\longrightarrow {}^{0}_{+1}\beta+{}^{127}_{55}Cs[/tex]

Barium goes underneath beta decay to form Ceaseum

[tex]\sf {}^{127}_{56}Ba\longrightarrow {}^0_{1}\beta+{}^{127}_{55}Cs[/tex]

Remember

Answer:

b) soil

heterogenous means you can pick out individual bits.

Answer:

because cotton have a good absorbing quality and can absorb water more which is used to mop the floor

Explanation:

Succinic acid most probably

Lets see why?

The molar mass is given as 118.084g/mol

Decimal next place i.e 10th place contains 0 means it has OH bonds in most of the cases.

So it's a hydrocarbon and more closely an alcohol or aldehyde

Let's verify

Approximately equal

The pH of the solution is 4.

pH value is the measure of the acidity and basicity of a solution.

It measures the [H+] ion liberated by an acid when dissolved in a solution.

It has a range of 0 to 14 , where 0 to 6.9 indicates acidity , 7 represents neutral solution , More than 7 up to 14 indicates alkaline solutions.

pH value is also used to predict the completion of a reaction .

It is given in the question that

The value of pOH = 10

pH = ?

It is known that the sum of pH and pOH is equal to 14.

pH + pOH = 14

pH + 10 = 14

pH = 4

Therefore the pH of the solution is 4.

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