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3 years ago

Complete this half-reaction.

Chemistry

1 answer:

Anna35 [415]3 years ago

3 0

Answer:

2Cr(s) → 2Cr3+(aq) + 3e⁻

Explanation:

The complete half reaction is 2Cr(s) → 2Cr3+(aq) + 3e⁻
The half reaction shows an oxidation reaction.
Oxidation refers to the loss of electrons by an atom of an element.
In this case, chromium atom undergoes oxidation by losing three electrons to form chromium ion.
Additionally, the oxidation number has increased from 0 to +1 which makes it an oxidation reaction.

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When of a certain molecular compound X are dissolved in of benzene , the freezing point of the solution is measured to be . Calc

puteri [66]

The question is incomplete. Here is the complete question.

When 2.10 g of a certain molecular compound X are dissolved in 65.0 g of benzene (C₆H₆), the freezing point of the solution is measured to be 3.5°C. Calculate the molar mass of X. If you need any additional information on benzene, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to 2 significant digits.

Answer: MM = 47.30 g/mol.

Explanation: There is a relationship between freezing point depression and molality. With this last one, is possible to calculate molar mass or molar weight of a compound.

Freezing Point Depression occurs when a solute is added to a solvent: the freezing point of the solvent decreases when a non-volatile solute is incremented.

Molality or molal concentration is a quantity of solute dissolved in a certain mass, in kg, of solvent. Its symbol is m and it's defined as

$m=\frac{moles(solute)}{kg(solvent)}$

Freezing point depression and molal are related as the following:

$\Delta T_{f}=K_{f}.m$

where

$\Delta T_{f}$ is freezing point depression of solution

$K_{f}$ is molal freezing point depression constant

m is molality

Now, to determine molar mass, first, find molality of the mixture:

$\Delta T_{f}=K_{f}.m$

$m=\frac{\Delta T_{f}}{K_{f}}$

For benzene, constant is 5.12°C/molal. Then

$m=\frac{3.5}{5.12}$

m = 0.683 molal

Second, knowing the relationship between molal and moles of solute, determine the last one:

$m=\frac{moles(solute)}{kg(solvent)}$

$mol(solute)=m.kg(solvent)$

mol(solute) = 0.683(0.065)

mol(solute) = 0.044 mol

The definition for Molar mass is the mass in grams of 1 mol of substance:

$n(moles)=\frac{m(g)}{MM(g/mol)}$

$MM=\frac{m}{n}$

In the mixture, there are 0.044 moles of X, so its molecular mass is

$MM=\frac{2.1}{0.044}$

MM = 47.30 g/mol

The molecular compound X has molecular mass of 47.30 g/mol.

7 0

4 years ago

What would happen to the oxygen atoms in ozone if the ozone layer were completely destroyed by ultraviolet radiation?

ale4655 [162]

When the oxygen atoms in ozone layer were destroyed by ultraviolet radiations the individual oxygen atoms will make bond with each other and form paired oxygen molecules again to form ozone.

What is the ozone layer?

Ozone layer has a high concentration of ozone (O3) in comparison to the rest of the atmosphere, although it is still low in comparison to other gases in the stratosphere.

The ozone layer contains less than ten parts per million of ozone, whereas the normal ozone concentration in the Earth's atmosphere is around 0.3 parts per million. The ozone layer is mostly found in the lower stratosphere.

To learn more about ozone layer click the given link

brainly.com/question/1449495

#SPJ4

5 0

1 year ago

A food chemist determines the concentration of acetic acid in a sample of apple vinegar by acid base titration. The density of t

Scilla [17]

Answer:

The concentration of acetic acid in the vinegar is 7,324 (%V/V)

Explanation:

The titration equation of acetic acid with NaOH is:

NaOH + CH₃COOH → CH₃COO⁻Na⁺ + H₂O

The moles required were:

1,024M×0,02500L = 0,02560 moles NaOH. These moles are equivalent (By the titration equation) to moles of CH₃COOH. As molar mass of CH₃COOH is 60,052g/mol, the mass in these moles of CH₃COOH is:

0,02560 moles CH₃COOH× $\frac{60,052g}{1mol}$ = 1,537g of CH₃COOH