Which unit is used for measuring atomic mass?

What is the role of a strong acid catalyst in an elimination reaction?

Ivan

Explanation:

An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one or two-step mechanism. The one-step mechanism is known as the E2 reaction, and the two-step mechanism is known as the E1 reaction.

Another definiton is;

Elimination reaction, any of a class of organic chemical reactions in which a pair of atoms or groups of atoms are removed from a molecule, usually through the action of acids, bases, or metals and, in some cases, by heating to a high temperature. It is the principal process by which organic compounds containing only single carbon-carbon bonds (saturated compounds) are transformed to compounds containing double or triple carbon-carbon bonds (unsaturated compounds).

Strong Acids play two key roles in elimination reactions:

1. Without the acid catalyst, the reaction is painfully slow.

2. Acid greatly facilitates elimination of the leaving group.

8 0

4 years ago

Which formula represents the compound commonly known as phosphine PH PH2 PH3 PH4

AveGali [126]

The answer is C). PH3

4 0

3 years ago

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Cesium-137 is part of the nuclear waste produced by uranium-235 fission. The half-life of cesium-137 is 30.2 years. How much tim

Dmitry_Shevchenko [17]

Answer:

There are required 70.1 years for the activity of a sample of cesium-137 to fall to 20.0 percent of its original value

Explanation:

The radioactive decay follows always first-order kinetics where its general law is:

Ln[A] = -Kt + ln[A]₀

Where [A] is actual concentration of the atom, k is rate constant, t is time and [A]₀ is initial concentration.

We can find rate constant from half-life as follows:

Rate constant:

t(1/2) = ln 2 / K

As half-life of Cesium-137 is 30.2 years:

30.2 years = ln 2 / K

K = 0.02295 years⁻¹

Replacing this result and with the given data of the problem:

Ln[A] = -Kt + ln[A]₀

Ln[A] = -0.02295 years⁻¹* t + ln[A]₀

Ln ([A] / [A₀]) = -0.02295 years⁻¹* t

As you want time when [A] is 20% of [A]₀, [A] / [A]₀ = 0.2:

Ln (0.2) = -0.02295 years⁻¹* t

70.1 years = t

<h3>There are required 70.1 years for the activity of a sample of cesium-137 to fall to 20.0 percent of its original value</h3>

8 0

4 years ago

The thin layer that separates a cells contents from the outside environment is the A.cell membrane b.nucleus c.cytoplasm D.endop

Vikentia [17]

The answer is A) Cell Membrane

8 0

4 years ago

If pure water boils at 99.8 degrees celcius, what is the expected elevated boiling point of a solution of 2.50g of CaCl2, in 50.

Alexeev081 [22]

INFORMATION:

We know that:

- pure water boils at 99.8 degrees celcius

And we must calculate the expected elevated boiling point of a solution of 2.50g of CaCl2, in 50.0mL (i.e., 50.0g) of H2O

STEP BY STEP EXPLANATION:

To calculate it, we need to use that:

Boiling point of solution = boiling point of pure solvent + boiling point elevation (ΔTb)

The elevation in boiling point (ΔTb) is proportional to the concentration of the solute in the solution. It can be calculated via the following equation.

$ΔTb=i\times k_b\times m$

Where,

- i is the Van’t Hoff factor

- Kb is the ebullioscopic constant

- m is the molality of the solute

From given information, we know that:

- i = 3

Now, the ebullioscopic constant (Kb) is often expressed in terms of °C * kg * mol^-1. The value of Kb for water is 0.512.

So, kb = 0.512 °C * kg * mol^-1

Then, we must calculate the molality

$\begin{gathered} Molality=\frac{\text{ moles of solute}}{\text{ kg of solvent}} \\ Molality=\frac{\frac{2.5g}{110.98\frac{g}{mol}}}{0.05kg}=0.45\frac{mol}{kg} \end{gathered}$

So, m = 0.45 mol/kg

Replacing the values in the formula for ΔTb

$\begin{gathered} ΔT_b=3\times0.512\frac{\degree C\cdot kg}{mol}\times0.45\frac{mol}{kg} \\ ΔT_b=0.69\degree C \end{gathered}$

Finally, the expected elevated boiling point of the solution would be

$\text{ Boling point of solution}=99.8\degree C+0.69\degree C=100.49\degree C$

ANSWER:

The expected elevated boiling point of the solution is 100.49 °C

3 0

1 year ago