Which set of elements has 4 valence electrons?

Answer: [tex]\Delta H_{vap}[/tex] = 55.1 kJ/mol

Explanation: Molar Enthalpy of Vaporization([tex]\Delta H_{vap}[/tex] ) is the energy needed to change 1 mol of a substance from liquid to gas at constant temperature and pressure.

For the 2-hydroxybiphenyl, there two temperatures and 2 pressures. In this case, use Clausius-Clapeyron equation:

[tex]ln\frac{P_{2}}{P_{1}}=\frac{\Delta H_{vap}}{R} (\frac{1}{T_{1}}-\frac{1}{T_{2}} )[/tex]

[tex]\Delta H_{vap}[/tex] is in J/mol:

1) Temperature in K

[tex]T_{1}=[/tex] 286  +273 = 559K

[tex]T_{2}[/tex] = 145 + 273 = 418K

2) Both pressure in Pa

[tex]P_{1}[/tex] = 101325Pa

[tex]P_{2}[/tex] = 14*133 = 1862Pa

Since molar enthalpy is in Joules, gas constant R is 8.3145J/mol.K

Replacing into the equation:

[tex]ln\frac{1862}{101325}}=\frac{\Delta H_{vap}}{8.3145} (\frac{1}{559}-\frac{1}{418} )[/tex]

[tex]ln(0.0184)=\frac{\Delta H_{vap}}{8.3145} (\frac{141}{233662} )[/tex]

[tex]\Delta H_{vap}=\frac{-3.9954*1942782.7}{-141}[/tex]

[tex]\Delta H_{vap}=55051.02[/tex]

[tex]\Delta H_{vap}=55051.02[/tex]

[tex]\Delta H_{vap}=55.1[/tex] kJ/mol

Using those values, molar enthalpy is 55.1 kJ/mol

Comparing to the CRC Handbook, which is [tex]\Delta H_{vap}=71[/tex] kJ/mol:

[tex]\frac{55.1}{71}[/tex] = 0.78

The calculated value is 0.78 times less than the CRC Handbook.

Explanation:

The location of a body with reference to a given point.

Answer:

9^3 i think so like 279

Explanation:

blah

Answer:

542 nanograms to grams = 5.42E-7g

Explanation:

Answer:

HI is a diatomic molecular compound known as hydrogen iodide or hydroiodic acid. It is a strong acid.

Answer:

We do something called hypothesis

Answer:

1. Make an observation.

2. Ask a question.

3. Propose a hypothesis.

4. Make predictions.

5. Test the predictions.

6. Iterate.

and if it can't be trsted the you did something wrong

Explanation:

The scientific method

At the core of biology and other sciences lies a problem-solving approach called the scientific method. The scientific method has five basic steps, plus one feedback step:

Make an observation.

Ask a question.

Form a hypothesis, or testable explanation.

Make a prediction based on the hypothesis.

Test the prediction.

Iterate: use the results to make new hypotheses or predictions.

The scientific method is used in all sciences—including chemistry, physics, geology, and psychology. The scientists in these fields ask different questions and perform different tests. However, they use the same core approach to find answers that are logical and supported by evidence.

Scientific method example: Failure to toast

Let's build some intuition for the scientific method by applying its steps to a practical problem from everyday life.

Answer:

C

Explanation:

its not A since its actually the atoms in exactly 12g of crabon-12

-not B since its grams not kilograms

-not D since it says "gram" which would mean that we measure the particles in a gram instead of a mole

Avogadro's number is the number of atoms, molecules, ions, formula units, or other particles in a mole of a substance. Therefore, option (c) is correct.

The Avogadro constant commonly denoted [tex]N_A[/tex] is the proportionality factor that the number of constituent particles such as molecules, atoms, or ions in one mole of a sample.

Avogadro's number is a constant with an exact value of 6.022 × 10²³ reciprocal moles. Avogadro's number is named by Stanislao Cannizzaro after the Italian scientist Amedeo Avogadro, who explained it four years after Avogadro's death.

The numerical value of the Avogadro constant is in reciprocal moles, a dimensionless number known as the Avogadro number. The value of the Avogadro constant, the mass of one mole of a chemical compound, in grams.

It is numerically equal to the average mass of one molecule of the compound in daltons. One dalton is 1/12 of the mass of one carbon-12 atom, which is the mass of one nucleon.

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Answer:

arc welder involves use of plasma in technology

The device involves the use of plasma in technology is "arc welder"

The 4th phase of matter, after solid, liquid, as well as gas, often been referred to as plasma. Inside a particular substance that is solid, liquid, or even gaseous, the electrons typically stick with almost the unique atomic nucleus.

Using electricity to generate sufficient heat to dissolve metal as well as then allowing the melted metals to cool, arc welding would be a technique for joining metals together.

Arc welding employs the plasma technology principle because the gas would be ionized.

Therefore, the correct answer will be option (a).

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Answer:

as gasoline is evaporated, this gasoline still remains as gasoline but in gaseous form when gas is being burned .

Answer:

The best thermometer to use for this temperature is the alcohol-in-a -glass thermometer.

Explanation:

The alcohol thermometer is a type of thermometer which uses ethanol as its thermometric liquid. This has some advantages at low temperatures because ethanol freezes at about −114.9 °C  that is (−174.82 °F).

Due to its low freezing point, it can still function effectively as a thermometric liquid, expanding and contracting properly based on the applied heat,  when dealing with temperature measurements that are at about -38.2°F.

Answer:On a sloped parking lot

Explanation:

Answer:

aluminum i think

Explanation:

Right now it's written in scientific notation, so you can just move the decimal place in 3.8 to the right 3 times (as it is times 10 to the third power) to get 3,800g.

The measurement 3.8 x 10³ grams could also be written as 3.8 kilograms.

A unit of measurement is a specified magnitude of a quantity that is established and used as a standard for measuring other quantities of the same kind. It is determined by convention or regulation.

As given in the problem we have to convert the measurement of 3.8 x 10³ grams into some different units,

1000 grams = 1 kilograms

1 gram = 1 /1000 kilograms

3.8 x 10³ grams = 3.8 x 10³ ×1 /1000 kilograms

                          =3.8 kilograms

Thus, the measurement 3.8 x 10³ grams could also be written as 3.8 kilograms.

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Answer:

concentration of diluted solution = 0.0125 ( ± 0.0002)M

Uncertainty = ± 0.0002  

Explanation:

Given that

Initial volume of Cu2+ = 4.00 (±0.01) mL

Initial molarity 0f Cu2+ = 0.302 (±0.004) M

transferred to  100.00 (±0.08) Class A volumetric flask

first we get amount of water added

100.00 (±0.08) - 4.00 (±0.01)  = 96 ± (0.09)

Now according to  law of dilution

The concentration of Cu2+ after adding water

M1V1 = M2V2

we substitute

0.302 (±0.004) * 4.00 (±0.01) = x * 96 ± (0.09)

Now the multiplication of two digits with uncertainty is

(0.004/0.302) * 100 =  1.32% ;    (0.01/4.00) * 100 = 0.25%

= [0.302 ( ± 1.32% )] * [ 4.00 ± (0.25%)]

= 1.208 ±(1.57%)

1.57/100 * 1.208 = 0.0189

so

= (1.208 ± 0.0189)

now substitute in our previous equation

1.208 ± (0.0189) = x * 96 ± (0.09)

x = 1.208 ± (0.0189) / 96 ± (0.09)

{ 0.09/96 * 100 = 0.094% }

so x = 1.208 ± (1.57%) / 96 ± (0.094% )  

x = 0.0125 ± ( 1.664)

now( 1.664/100 * 0.0125)

= ± 0.000208

Hence

concentration of diluted solution = 0.0125 ( ± 0.0002)M

Uncertainty = ± 0.0002  

Answer:

A. Controlled variable

Explanation:

a controlled variable or a constant variable is a variable that doesnt change during an experiment

Answer:

HELIUM

Explanation:

HELIUM HAS 2 PROTON I

Answer: To evaluate the claim in the advertisement, Travis should look at the data for the control group to see how much the fish grew without the new food.

Explanation:

Answer:

Option B - 2

Explanation:

In Crystal lattices, there are different types of unit cells namely;

- Hexagonal Closest Packed (HCP)

- Face Centred Cubic (FCC)

- Body Centred Cubic (BCC)

- Simple Centred Cubic (SC)

Now, each of them have a coordination number and also number of atoms per unit cell.

For this question, we are restricted to the body-centered cubic (bcc) unit cell which has a coordination number of 8 and contains 2 atoms per unit cell.

Answer:

B) 2.

Explanation:

They have 8 1/8 atoms on the edge that add to get 1 atom. Plus one whole atom inside. 1+1=2

Answer:

adding more water to the container

Explanation: because it would cause it to soak up the fluid to created a substance again

Answer:

adding more water to the container and iflamates the cells

Explanation:

Answer:

[tex]Sn_2O[/tex]

Explanation:

Hello,

In this case, given the mass of the sample and mass of tin we can compute the mass of oxygen via:

[tex]m_O=0.534g-0.500g=0.034g[/tex]

Thus, by using the atomic bas of tin and oxygen we can compute their moles:

[tex]n_{Sn}=0.500gSn*\frac{1molSn}{118.8gSn} =0.00421mol\\\\n_O=0.034gO*\frac{1molO}{16gO}=0.002125mol[/tex]

Next, we need to divide both moles by the moles of oxygen as those are the smallest in order to compute the subscript in the chemical reaction:

[tex]Sn=\frac{0.00421}{0.002125}=2\\ \\O=\frac{0.002125}{0.002125}= 1[/tex]

Therefore, empirical formula of the oxide should be:

[tex]Sn_2O[/tex]

Best regards.

Answer:

1 and a half cups

Explanation:

12 ounces is equivalent to 1.5 cups

Answer:

Explanation:

The major difference between pure and applied chemistry is the purpose and intent of the study.

Pure chemistry deals with the study of matter, matter transformations, and interactions between the different materials of the world, for only the sake of gaining empirical knowledge about the various substances that exist in the world. It does not really seek to apply this knowledge to do anything industrial.

Applied chemistry is the study of chemistry with the aim of utilizing this knowledge to solve the various problems that man faces. This approach of study is not for knowledge sake alone, rather it is for industrial application

The major difference between pure and applied chemistry is the purpose and intent of the study.

Pure chemistry deals with the study of matter, matter transformations, and interactions between the different materials of the world, for only the sake of gaining empirical knowledge about the various substances that exist in the world. It does not really seek to apply this knowledge to do anything industrial.

Applied chemistry is the study of chemistry with the aim of utilizing this knowledge to solve the various problems that man faces. This approach of study is not for knowledge sake alone, rather it is for industrial application.

Thus,the major difference between pure and applied chemistry is the purpose and intent of the study.

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Answer:

This question is incomplete, the complete question is; assuming that the solution has a specific heat of 4.18 J/g°C

The answer is 381.67 J/g

Explanation:

Enthalpy change denoted by ΔH can be calculated using the formula;

ΔH = m × c × ΔT

Where; m= mass of reactants

c= specific heat

ΔT = change in temperature

ΔT = T2 - T1

ΔT = 32.76 - 19.3

ΔT = 13.46 °C

mass of reactants= 85.6 + 14.8 = 100.4g, c = 4.18J/g°C

Hence; ΔH = m × c × ΔT

ΔH = 100.4 × 4.18 × 13.46

ΔH = 5648.78J

Enthalpy change per gram of potassium hydroxide dissolved in the water is;

ΔH = 5648.78/14.8

ΔH = 381.67 J/g

The enthalpy change per gram of potassium hydroxide dissolved in the water is 382 J/g

Q = MCΔT

Q = 100.4 × 4.184 × 13.46

Q = 5654.19 J

ΔH = Q / g

ΔH = 5654.19 / 14.8

ΔH = 382 J/g

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Answer:

1.1 L

Explanation:

Volume and pressure are inversly proportional to each other meaning as volume increase, pressure decreases or the other way around. Use the equation V1P1=V2P2. So, it'll be (2.5L)(94.0kpa)=(207kPa)(V2). Thereby it is (2.5*94.0)/207= V2 = 1.1L. Don't forget your sigfigs which will be to 2 sigs.