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3 years ago

14

An atomic number stands for the number of _____. neutrons in the nucleus of an atom protons in the nucleus of an atom valence el

ectrons in an atom protons plus neutrons in the nucleus of an atom

1 answer:

Effectus [21]3 years ago

5 0

Answer:

atoms or electrons

Explanation:

but l guess electrons is the best answer

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The heat of fusion AH, of ethyl acetate (C4H802) is 10.5 kinol. Calculate the change in entropy as when 398. g of ethy, acetate

Hitman42 [59]

<u>Answer:</u> The entropy change of the ethyl acetate is 133. J/K

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of ethyl acetate = 398 g

Molar mass of ethyl acetate = 88.11 g/mol

Putting values in above equation, we get:

$\text{Moles of ethyl acetate}=\frac{398g}{88.11g/mol}=4.52mol$

To calculate the entropy change for different phase at same temperature, we use the equation:

$\Delta S=n\times \frac{\Delta H_{fusion}}{T}$

where,

$\Delta S$ = Entropy change = ?

n = moles of ethyl acetate = 4.52 moles

$\Delta H_{fusion}$ = enthalpy of fusion = 10.5 kJ/mol = 10500 J/mol (Conversion factor: 1 kJ = 1000 J)

T = temperature of the system = $84.0^oC=[84+273]K=357K$

Putting values in above equation, we get:

$\Delta S=\frac{4.52mol\times 10500J/mol}{357K}\\\\\Delta S=132.9J/K$

Hence, the entropy change of the ethyl acetate is 133. J/K

7 0

3 years ago

Give the structure of the principal organic product formed by free-radical bromination of 2,2,4−trimethylpentane.

Fudgin [204]

the principal organic product formed by free-radical bromination of 2,2,4−trimethylpentane is 2-bromo-2,4,4-trimethylpentane.

what is free radical halogenation?

A substitution reaction in which a hydrogen atom is replaced with a halogen atom, via a free radical reaction mechanism. when this reaction is carrid out by bromine radical, it is called free radicle bromination. When bromine ( $Br{2}$ ) treated with light (hν) it comes to homolytic cleavage of the Br-Br bond and give rise to bromine radicles.

free-radical bromination of 2,2,4−trimethylpentane

Bromination of an alkane includes the substitution of a bromine atom for a hydrogen atom. The following stages will be taken by 2,2,4-trimethylpentane during this reaction:

Initiation reaction: The production of a bromine free radical requires the initiation of heat or light.

$Br - Br$ ⇒ $2Br$ ·

Propagation: This reaction relies heavily on hydrogen. This reaction is impossible if hydrogen is not present. Because tertiary free radicals are more stable than secondary and primary free radicals, they are favoured in this reaction.

Termination: The remaining free radical of bromide reacts with the tertiary free radical of 2,2,4-trimethylpentane to form 2-bromo-2,4,4-trimethylpentane.

the principal organic product formed by free-radical bromination of 2,2,4−trimethylpentane is 2-bromo-2,4,4-trimethylpentane.

To know more about free radical halogenation, check out:

brainly.com/question/13046867

#SPJ4

7 0

1 year ago

Last week you reacted magnesium with a hydrochloric acid aqueous solution and hydrogen gas was produced. Let's say that you coll

miv72 [106K]

Answer:

69.8 kilo Pasacl is the pressure of the hydrogen gas.

Explanation:

$Mg+2HCl\rightarrow MgCl_2+H_2$

Pressure at which hydrogen gas collected = p = 101.2 kilo Pascals

Vapor pressure water = $p^o$ = 31.4 kilo Pascals

The pressure of hydrogen gas = P

The pressure at which gas was collected was sum of vapor pressure of water and hydrogen gas.

$p=P+p^o$

$P =p-p^o=101.2 kPa-31.4 kPa=69.8 kPa$

69.8 kilo Pasacl is the pressure of the hydrogen gas.

3 0

3 years ago

If 56.8 ml of bacl2 solution is needed to precipitate all the sulfate ion in a 554 mg sample of na2so4 (forming baso4), what is

IrinaVladis [17]

<span>0.0687 m The balanced equation is BaCl2 + Na2SO4 ==> BaSO4 + 2 NaCl Looking at the equation, it indicates that there's a 1 to 1 ratio of BaCl2 and Na2SO4 in the reaction. So the number of moles of each will be equal. Now calculate the number of moles of Na2SO4 we had. Start by looking up atomic weights. Atomic weight sodium = 22.989769 Atomic weight sulfur = 32.065 Atomic weight oxygen = 15.999 Molar mass Na2SO4 = 2 * 22.989769 + 32.065 + 4 * 15.999 = 142.040538 g/mol Moles Na2SO4 = 0.554 g / 142.040538 g/mol = 0.003900295 mol Molarity is defined as moles per liter, so let's do the division. 0.003900295 mol / 0.0568 l = 0.068667165 mol/l = 0.068667165 m Rounding to 3 significant figures gives 0.0687 m</span>

3 0

3 years ago

Explain how are elements classified and provide an example

swat32

By nonmetals, metals, and gases

4 0

2 years ago