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3 years ago

which atom has a change in oxidation number of -3 in the following redox reaction K2Cr2O7 + H2O +S --> KOH + Cr2O3 +SO2

1 answer:

6 0

You have to calculate the oxidation estates of the atoms in each compound.

I will start with K2Cr2O7 because I believe that Cr is the best candidate to reduce its oxidation number in 3 units.

In K2Cr2O7:

- K has oxidation state of 1+, then K2 has a charge of 2* (1+) = 2+.

- O has oxidation state of 2*, then O7 has a charge of 7* (2-) = 14-.

That makes that Cr2 has charge of 14 - 2 = +12, so each Cr has +12/2 = +6 oxidation state.

In Cr2O3:

- O has oxidation state of 2-, then O3 has charge 3 * (2-) = - 6

- Then, Cr2 has charge 6+, and each Cr has charge 6+ / 2 = 3+.

So, we have seen that Cr reduced its oxidation state in 3 units, from 6+ to 3+.

Answer: Cr has a change in oxidation number of - 3.

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A solution is made by adding 35.5 mL of concentrated hydrochloric acid ( 37.3 wt% , density 1.19 g/mL1.19 g/mL ) to some water i

erastova [34]

Answer:

1.73 M

Explanation:

We must first obtain the concentration of the concentrated acid from the formula;

Co= 10pd/M

Where

Co= concentration of concentrated acid = (the unknown)

p= percentage concentration of concentrated acid= 37.3%

d= density of concentrated acid = 1.19 g/ml

M= Molar mass of the anhydrous acid

Molar mass of anhydrous HCl= 1 +35.5= 36.5 gmol-1

Substituting values;

Co= 10 × 37.3 × 1.19/36.5

Co= 443.87/36.6

Co= 12.16 M

We can now use the dilution formula

CoVo= CdVd

Where;

Co= concentration of concentrated acid= 12.16 M

Vo= volume of concentrated acid = 35.5 ml

Cd= concentration of dilute acid =(the unknown)

Vd= volume of dilute acid = 250ml

Substituting values and making Cd the subject of the formula;

Cd= CoVo/Vd

Cd= 12.16 × 35.5/250

Cd= 1.73 M

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3 years ago

Most strings of outdoor lights are wired in a parallel circuit. Which of the following is the best reason why a string of outdoo

sergey [27]

Answer:

C.If one light in the string burns out in a parallel circuit, the rest of the lights will continue to shine.

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2 years ago

An inclined plane is a machine why?

attashe74 [19]

Answer:

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2 years ago

write down the name and molecular formula of the compound which gives hydrogen ion and chloride ion in the solution state.

podryga [215]

Answer:

Hydochloric acid

HCl

Explanation:

The name of the compound that gives hydrogen ion and chloride ions in the solution state is Hydrochloric acid.

Hydrochloric acid is made up of one atom of hydrogen and 1 atom of chlorine. We can also say, it is made up of 1 mole of hydrogen and 1 mole of chlorine.

The formula of this compound is HCl;

In solution:

HCl $_{aq}$ → H⁺ + Cl⁻