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Nitella [24]
3 years ago
14

Plz help me.....im new here

Chemistry
2 answers:
BabaBlast [244]3 years ago
5 0

Answer:

<h2><em><u>Option</u></em><em><u> </u></em><em><u>3rd</u></em></h2>

Fe2S3

Explanation:

As, the ionic valency of Iron (Fe) that is + 3 interchanges with the ionic valency of Sulphide that is - 2 to form-

Fe2S3

yan [13]3 years ago
3 0

Answer:

Fe2S3

Explanation:

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Which types of changes must follow the law of conservation of mass? (2 points)
Oksana_A [137]
Both Physical and chemical changes.
4 0
3 years ago
What is paper chromatography? Calculate the Rr value of a colored dye that traveled 52 mm on a chromatography strip while the so
Karo-lina-s [1.5K]

Answer:

Paper chromatography is a basic technique of chromatography. It consist in the separation of the mixe components using a solvent.

Explanation:

Paper chromatography is a basic technique of chromatography. It consists in the separation of the mixed components using a solvent.

Paper chromatography consists of put some dot of the mix using a glass capillary into a specialized paper, generally made of cellulose, this is called a stationary phase.

Then you put this paper into a camera of glass named, chromatography camera, where previously contain a solvent. The solvent also know as a mobile phase, the type can be defined before the test and involves a study of the kind of the mix, and the compound you want to separate.

The chromatography camera has to be closed all the time during the test, and you can't move at all because the movement of the solvent can alternate the result.

Very often, the solution of the solvent is a mix of different liquid substances with different polarities.

When the stationary phase put into the camera, the solvent starts to move up over the paper, until the separation of the compounds is observable.

the Rf is a value who relates the move of the mobile phase with the move of the distance traveled by the substance tested.

To undersant the paper chromatography, you can watch the images attached.

The first is an image of the chromatography camera.

The second one is an image of a cellulose paper after the chromatography is done. You can watch the dots who indicates the traveling of the compound across the paper.

The third one can show you the evolutions of paper chromatography, from the beginning to the end.

To calculate the Rf value you have to use the equation:

Rf = distance traveled by the substance/distance traveled by the solvent/

<u>Rf = 52mm/81mm =0.64</u>

<u></u>

3 0
3 years ago
Calculate the standard enthalpy change for the reaction at 25 ∘ C. Standard enthalpy of formation values can be found in this li
meriva

Answer:

The standard enthalpy change for the reaction at 25^{0}\textrm{C} is -2043.999kJ

Explanation:

Standard enthalpy change (\Delta H_{rxn}^{0}) for the given reaction is expressed as:

\Delta H_{rxn}^{0}=[3mol\times \Delta H_{f}^{0}(CO_{2})_{g}]+[4mol\times \Delta H_{f}^{0}(H_{2}O)_{g}]-[1mol\times \Delta H_{f}^{0}(C_{3}H_{8})_{g}]-[5mol\times \Delta H_{f}^{0}(O_{2})_{g}]

Where \Delta H_{f}^{0} refers standard enthalpy of formation

Plug in all the given values from literature in the above equation:

\Delta H_{rxn}^{0}=[3mol\times (-393.509kJ/mol)]+[4mol\times (-241.818kJ/mol)]-[1mol\times (-103.8kJ/mol)]-[5mol\times (0kJ/mol)]=-2043.999kJ

4 0
3 years ago
The specific heat for liquid ethanol is 2.46 J/(g•°C). When 210 g of ethanol is cooled from
avanturin [10]

Answer:

a) heat it from 23.0 to 78.3

q = (50.0 g) (55.3 °C) (2.46 J/g·°C) =  

b) boil it at 78.3

(39.3 kJ/mol) (50.0 g / 46.0684 g/mol) =  

c) sum up the answers from the two calculations above. Be sure to change the J from the first calc into kJ

Explanation:

3 0
3 years ago
A thermos bottle uses a ______ to keep heat in the thermos
attashe74 [19]

Answer:

a thermos bottle uses a vacuum to keep heat in the thermos.

4 0
2 years ago
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