Which change of state involves a release of energy?

Answer:

Covalent bonding occurs when electrons are shared between atoms. Double and triple covalent bonds occur when four or six electrons are shared between two atoms, and they are indicated in Lewis structures by drawing two or three lines connecting one atom to another.

Explanation:

Answer:0

Explanation:

Answer:

Pressure = 0.62 atm

Explanation:

[tex]V_{1}[/tex] = 85 [tex]cm^{3}[/tex], [tex]P_{1}[/tex] = 1.45 atm,  [tex]T_{1}[/tex] = 310 K, [tex]V_{2}[/tex] = 180 [tex]cm^{3}[/tex], [tex]T_{2}[/tex] = 280 K.

Applying the general gas law,

[tex]\frac{P_{1} V_{1} }{T_{1} }[/tex] = [tex]\frac{P_{2} V_{2} }{T_{2} }[/tex]

[tex]\frac{1.45*85}{310}[/tex] = [tex]\frac{P_{2}*180 }{280}[/tex]

[tex]P_{2}[/tex] = [tex]\frac{1.45*85*280}{180*310}[/tex]

   = [tex]\frac{34510}{55800}[/tex]

   = 0.62

[tex]P_{2}[/tex]  = 0.62 atm

The pressure when the volume is increased and the temperature reduced to the given values is 0.62 atm.

Answer:

22.6%

Explanation:

I just answered and got it right

Answer:

[tex]m_{Fe(OH)_3} = 0.891gFe(OH)_3[/tex]

Explanation:

Hello!

In this case, given the chemical reaction:

[tex]3NaOH(aq)+Fe(NO_3)_3(aq)\rightarrow 3NaNO_3(aq)+Fe(OH)_3(s)[/tex]

In such a way, given the volumes and molarities of each reactant, we can compute the moles of produced iron (III) hydroxide by each of them, via the 3:1 and 1:1 mole ratios:

[tex]n_{Fe(OH)_3}^{by\ NaOH}=0.0500L*0.500\frac{molNaOH}{L}*\frac{1molFe(OH)_3}{3molNaOH} =0.00833molFe(OH)_3\\\\n_{Fe(OH)_3}^{by\ Fe(NO_3)_3}=0.0750L*0.200\frac{molFe(NO_3)_3}{L}*\frac{1molFe(OH)_3}{1molFe(NO_3)_3} =0.0150molFe(OH)_3[/tex]

It means that the sodium hydroxide is the limiting reactant and 0.00833 moles of iron (III) hydroxide are produced; thus, the required mass is:

[tex]m_{Fe(OH)_3}=0.00833molFe(OH)_3*\frac{106.87gFe(OH)_3}{1molFe(OH)_3} \\\\m_{Fe(OH)_3} = 0.891gFe(OH)_3[/tex]

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The volume required : 0.2 L

Given

500ml of 0.1M potassium dichromate (vii)

0.25 solution

Required

The volume

Solution

We can use dilution formula :

M₁V₁=M₂V₂

M₁ = 0.25

M₂ = 0.1

V₂ = 500 ml = 0.5 L

The initial volume taken :

V₁=(M₂V₂)/M₁

V₁=(0.1 x 0.5)/0.25

V₁=0.2 L

Answer:

*helps*

Explanation:

A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements.

Answer:

the blanket of gases that surrounds Earth and some other planets

Explanation:

The best definition of the atmosphere is that it is a portion of the earth that is a made up of a blanket of gases.

Answer:

Chemical formula of the compound = K₂O

Explanation:

Given:

Number of potassium cation = 2

Number of oxygen anion = 1

Cross valency

Symbol of potassium = k

Symbol of oxygen = o

So;

Chemical formula of the compound = K₂O

Answer:

Glucose molecules

Explanation:

Considering the solution of mole fraction, molality and molarity, you obtain that:

(a) the mole fraction of thiophene in the solution is 0.039.

(b) the molality of thiophene in the solution 0.4429 [tex]\frac{moles}{kg}[/tex].

(c)  the molarity of thiophene in the solution is 0.373[tex]\frac{moles}{L}[/tex].

You know that:

The molar fraction is a way of measuring the concentration that expresses the proportion in which a substance is found with respect to the total moles of the solution.

Being the molar mass of each compound equals to:

the number of moles of each compound can be calculated as:

The total moles is obtained from the addition of the moles of the solute (C₄H₄S) and the solvent (C₇H₈):

total moles = moles C₄H₄S + moles C₇H₈ = 0.096 moles + 2.35 moles = 2.45 moles

Then, the mole fraction of thiophene in the solution can be calculated as:

[tex]mole fraction of thiophene=\frac{0.096 moles}{2.45 moles}[/tex]

Solving:

mole fraction of thiophene= 0.039

Finally, the mole fraction of thiophene in the solution is 0.039.

Molality is the ratio of the number of moles of any dissolved solute to kilograms of solvent.

The Molality of a solution is determined by the expression:

[tex]Molality=\frac{number of moles of solute}{kilograms of solvent}[/tex]

In this case, you know:

Replacing:

[tex]Molality C_{4} H_{4}S =\frac{0.096 moles}{0.21675 kg}[/tex]

molality C₄H₄S= 0.4429 [tex]\frac{moles}{kg}[/tex]

Finally, the molality of thiophene in the solution 0.4429 [tex]\frac{moles}{kg}[/tex].

Molarity is the number of moles of solute that are dissolved in a certain volume and is determined by the following expression:

[tex]Molarity=\frac{number of moles of solute}{volume}[/tex]

Assuming that the volumes of solute and solvent are additive, you can add the volume of C₄H₄S and C₇H₈.

But first, you need yo know the volume of C₄H₄S, which can be calculated from the mass and density:

[tex]Volume C_{4} H_{4}S =8.10 grams\frac{1 mL}{1.065 grams}[/tex]= 7.606 mL= 0.007606 L

Then, the total volume of the solution is calculated as:

total volume of the solution= volume C₇H₈ + volume C₄H₄S

total volume of the solution= 0.250 L + 0.007606 L = 0.257606 L

So, the molarity of thiophene in the solution can be calculated as:

[tex]Molarity C_{4} H_{4} S=\frac{number of moles of C_{4} H_{4} S}{totalvolumeof the solution}[/tex]

Replacing:

[tex]Molarity C_{4} H_{4} S=\frac{0.096 moles}{0.257606 L}[/tex]

Solving:

Molarity C₄H₄S= 0.373 [tex]\frac{moles}{L}[/tex]

Finally, the molarity of thiophene in the solution is 0.373[tex]\frac{moles}{L}[/tex].

In summary, you get:

(a) the mole fraction of thiophene in the solution is 0.039.

(b) the molality of thiophene in the solution 0.4429 [tex]\frac{moles}{kg}[/tex].

(c)  the molarity of thiophene in the solution is 0.373[tex]\frac{moles}{L}[/tex].

Learn more about

Answer - B Atoms in the original substances are arranged in a different way to make new substances

Answer:

Establish and Use a Secure Connection

Use SSH Keys Authentication

Secure File Transfer Protocol

Secure Sockets Layer Certificates

Use Private Networks and VPNs

Explanation:

Answer:

A Variac or Powermite; gradually; 50-60%.

Explanation:

A chemical reaction can be defined as a chemical process which typically involves the transformation or rearrangement of the atomic, ionic or molecular structure of an element through the breakdown and formation of chemical bonds to produce a new compound or substance.

Some of the laboratory apparatus (equipment) used for conducting a chemical reaction are conical flask, Bunsen burner, beaker, tongs, crucible, round bottom flask etc.

In order to heat a round bottom flask in a heating mantle, plug the heating mantle into a Variac or Powermite which is typically used for controlling the level of temperature. Turn the heat up gradually, and do not exceed 50-60% of the maximum output of the device, so as to avoid any electrical issues such as overloading, short-circuit etc.

The safety precautions that must be taken when using a round bottom flask are;

I. A proper inspection of the round bottom flask for cracks, irregularities or any imperfection.

II. Ensure you avoid heating the flask while it is closed.

III. When suspending the round bottom flask on a stand, you should ensure that you use a clamp for stability.

Answer:

it will A. d. e. f option above

Answer:

Upwelling! Its the process where the deep cold water rises to the surface! :)

Explanation:

Hope this helps! :)

Answer:

upwelling

Explanation:

Answer:

double replacement

Explanation:

The reaction shown is a double replacement reaction.

It is also known as double decomposition or metathesis reaction.

In such a reaction, there is an actual exchange of partners to form new compounds.

One of the following is the driving force for such reaction:

Answer:

Calcium

Explanation:

The symbol for the element with a mass number of 27 is actually Al for Aluminum instead of Co for Cobalt. Mass number refers to atomic mass, not atomic number.

Aluminum has an atomic mass of 26.982 or 27.

The letters to unscramble are I, M, C, Al, U, and C.

The mystery element is Calcium.

Hope that helps.

Answer:

In atomic number

And size

And nature of each (metal, non, or metalloide)

[tex]\Large \boxed{\sf by \ their \ properties}[/tex]

Every element has a set of particular characteristics. Each has a unique atomic and mass number because they contain a different ratio of protons and neutrons. The number of protons in an element mirrors the element's atomic number. The mass number equals the sum of the element's protons and neutrons.

According to increasing atomic numbers, chemical elements get organized. Periods and groups are the names of the horizontal rows and vertical columns, respectively. The chemical characteristics of elements within the same group are comparable due to their similar valency and number of outer electrons.

Answer:

Read this section of the text:

These raptors eat primarily flying insects, so they do most of their hunting on the wing.

What does primarily mean in this sentence?

Explanation:

I'm bored

Answer:

Taste comes from the stimulation of chemical receptors in nerve cells on the tongue by particular chemical structures of substances. If there are no chemical structures pertaining to any of the chemical sensors, the substance would appear to be tasteless. All of these chemicals interact with the sensors with the help of the medium of saliva which has a lot of water. For example: the salt sensors might be susceptible to ions and the sweet sensors might be susceptible to hydroxyl groups on the sugars.

Now, taste is not a very precise field of study. A same substance may taste subtly different to different people. Can we be sure that water has no taste? The chemical sensors are always exposed to water. It might be that there are no sensors for water. It might also be that the signal for water is negated as a background signal. If water did have a particular taste, one thing is for certain, we would be tasting water in every bite of food and even at times when we are not eating as we always have saliva in your mouth.

Hope this helps, have a wonderful day/night, and stay safe!

The number of atoms in 1 mole of carbon equals the number of atoms in 1 mole of boron is false because the molar mass of carbon is different from that of boron. Option A is correct.

From the listed option the number of atoms in 1 mole of carbon equals the number of atoms in 1 mole of boron is false because the molar mass of carbon is different from that of boron

Learn more on moles here: https://brainly.com/question/24256751

Answer:

A. Theoretical yield of C is 9.03 g

B. Mass of B consumed is 5.53 g

Explanation:

A. Determination of the theoretical yield of C.

Actual yield of C = 6.5 g

Percentage yield of C = 72.%

Theoretical yield of C =?

Percentage yield = Actual yield /Theoretical yield × 100

72% = 6.5 / Theoretical yield

72 / 100 = 6.5 / Theoretical yield

Cross multiply

72 × Theoretical yield = 100 × 6.5

72 × Theoretical yield = 650

Divide both side by 72

Theoretical yield = 650 / 72

Theoretical yield = 9.03 g

Therefore, the theoretical yield of C is 9.03 g

B. Determination of the mass of B consumed.

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

A + B —> C

Mass of A = 3.5 g

Mass of C = 9.03 g

Mass of B =?

A + B = C

3.5 + B = 9.03

Collect like terms

B = 9.03 – 3.5

B = 5.53 g

Thus, the mass of B consumed in the reaction is 5.53 g

Answer:

0.089

Explanation:

2.5/ 14= .178 then 0.178/ 2 again and you get 0.089

The moles of nitrogen in 2.5 grams of the compound is 0.089 moles. Thus option A is correct.

Moles can be calculated as the ratio of mass to molecular mass.

Moles = [tex]\rm \dfrac{weight}{molecular\;weight}[/tex]

The mass of Nitrogen = 14 g/mol

The mass of diatomic nitrogen = 2 [tex]\times[/tex] mass of nitrogen

The mass of diatomic nitrogen = 2 [tex]\times[/tex] 14 g/mol

The mass of diatomic nitogen = 28 g/mol

The molecular weight of Nitrogen = 28g/mol

Given, the mass of Nitrogen = 2.5 g

Moles of nitrogen = [tex]\rm \dfrac{2.5}{28}[/tex]

Moles of Nitrogen = 0.089 moles.

The moles of nitrogen in 2.5 grams of the compound is 0.089 moles. Thus option A is correct.

For more information about a mole, refer to the link:

https://brainly.com/question/21898305

Answer:

only 1 parent is needed! and the offspring is a identical copy of the parent

Answer:

32.4%

Explanation:

%Yield = Actual Yield/Theoretical Yield x 100% = (12.7/39.2)100% = 32.4%