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swat32
3 years ago
14

What is the oxidation number of chromium in Cr2O7 4-?

Chemistry
2 answers:
Softa [21]3 years ago
8 0

<u>Answer:</u> The oxidation state of chromium in the given compound is +5.

<u>Explanation:</u>

Oxidation state is defined as the number which is given to an atom when it looses or gains electron. It is written as a superscript.

If the element gains electron, it will attain a negative oxidation state and if the element looses electrons, it will attain a positive oxidation state.

We are given a chemical compound having chemical formula of Cr_2O_7^{4-}

We take the oxidation state of chromium atom be 'x'.

Oxidation state of oxygen atom = -2

Overall charge on chemical compound = -4

Evaluating the oxidation state of chlorine atom:

2(x)+7(-2)=-4\\\\x=+5

Hence, the oxidation state of chromium in the given compound is +5.

nignag [31]3 years ago
3 0

Answer:

C. +5

Explanation:

Oxygen is always -2. And the sum of the oxidation numbers must be equal to the charge. So:

2x + 7(-2) = -4

2x - 14 = -4

2x = 10

x=5

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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
What is the number assigned to an element on the Periodic Table?
spayn [35]

Answer:

Element Atomic Number One number you will find on all periodic tables is the atomic number for each element.

Explanation:

<em>hope it helps :))</em>

6 0
2 years ago
An empty beaker weighs 25.91 g. When completely filled with water, the beaker and its contents have a total mass of 333.85 g. Wh
Finger [1]

Answer:

The beaker holds 307.94  mL

Explanation:

As we know that the volume that beaker hold is the volume of water that occupied by it.

For this first we have to find mass of the water in the beaker

This can be calculated by the subtraction of beaker's weight from the weight of beaker and water.

     weight of water (m) = total weight - weight of beaker

Empty weight of beaker = 25.91 g

Weight of beaker with water = 333.85 g

Weight of water = 333.85 - 25.91 = 307.94 g

Density of water = 1 g/mL

We have

      Mass = Volume x density

      307.94  = Volume x 1

      Volume = 307.94  mL

The beaker holds 307.94  mL

3 0
3 years ago
Which of the following is a statement of Hess's law?
attashe74 [19]

Answer:

C

Explanation:

the enthalpy of reaction is independent of the reaction path

7 0
2 years ago
A chemist has 60ml of a 3M NaCl solution. He needs to dilute it so the Molarity is 1M NaCl. How much water does he need to add?
REY [17]

Answer:

80 ml the right answer

Explanation:

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8 0
3 years ago
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