Answer:

**Answer:**

a) 1.866 × 10 ⁻¹⁹ J b) 3.685 × 10⁻¹⁹ J

**Explanation:**

the constants involved are

h ( Planck constant) = 6.626 × 10⁻³⁴ m² kg/s

Me of electron = 9.109 × 10 ⁻³¹ kg

speed of light = 3.0 × 10 ⁸ m/s

a) the Ek ( kinetic energy of the dislodged electron) = 0.5 mu²

Ek = 0.5 × 9.109 × 10⁻³¹ × ( 6.40 × 10⁵ )² = 1.866 × 10 ⁻¹⁹ J

b) Φ ( minimum energy needed to dislodge the electron ) can be calculated by this formula

hv = Φ + Ek

where Ek = 1.866 × 10 ⁻¹⁹ J

v ( threshold frequency ) = c / λ where c is the speed of light and λ is the wavelength of light = 358.1 nm = 3.581 × 10⁻⁷ m

v = ( 3.0 × 10 ⁸ m/s ) / (3.581 × 10⁻⁷ m ) = 8.378 × 10¹⁴ s⁻¹

hv = 6.626 × 10⁻³⁴ m² kg/s × 8.378 × 10¹⁴ s⁻¹ = 5.551 × 10⁻¹⁹ J

5.551 × 10⁻¹⁹ J = 1.866 × 10 ⁻¹⁹ J + Φ

Φ = 5.551 × 10⁻¹⁹ J - 1.866 × 10 ⁻¹⁹ J = 3.685 × 10⁻¹⁹ J

Practice the Skill 21.15b When the following ketone is treated with aqueous sodium hydroxide, the aldol product is obtained in poor yields. In these cases, special distillation techniques are used to increase the yield of aldol product. Predict the aldol addition product that is obtained, and propose a mechanism for its formation. For the mechanism, draw the curved arrows as needed. Include lone pairs and charges in your answer. Do not draw out any hydrogen explicitly in your products. Do not use abbreviations such as Me or Ph.

In an endothermic reaction what is true of the enthalpya) is has increased b) is has decreased c)it has remained unchargedd) it has at minimum been halved

Which is more water soluble hexanoic acid or sodium hexanoate?

What is the pOH of a 7.9 x 10 ^-4 M OH- solution? pOH= ?

Guys i need a long inforation about.... "Formation of colloids" Please and thank you

In an endothermic reaction what is true of the enthalpya) is has increased b) is has decreased c)it has remained unchargedd) it has at minimum been halved

Which is more water soluble hexanoic acid or sodium hexanoate?

What is the pOH of a 7.9 x 10 ^-4 M OH- solution? pOH= ?

Guys i need a long inforation about.... "Formation of colloids" Please and thank you

Give an example of a substance that is MORE dense in its solid state when compared to its liquid state.

**Answer: Wax**

**Explanation:**

**Density** is defined as the mass contained per unit volume.

Usually solids are more denser than liquid, as molecules in solid are more strongly packed and thus have more mass per unit volume.

Liquids on the other hand contain molecules which are less tightly bound and thus thus contain less mass per unit volume as compared to solid.

Example: Solid wax is more denser than liquid wax.

If a sample contains 84.0 % of the R enantiomer and 16.0 % of the S enantiomer, what is the enantiomeric excess of the mixture

**Answer:**

enantiomeric excess = 68%

**Explanation:**

Enantiomeric excess is a value used to determine the purity of chiral molecules. It is possible to determine enantiomeric excess (ee) using:

ee = R - S / R + S * 100

*Where R is the mass (In this case percentage) of the R enantiomer and S of the S enantiomer.*

Replacing with values of the problem:

ee = 84% - 16% / 84% + 16% * 100

The enantiomeric excess of the mixture, defined as the difference between the concentrations of the R and S enantiomers, is 68.0%.

The **enantiomeric excess (ee)** is defined as the absolute difference between the mole percentage of the major enantiomer and the minor enantiomer in a mixture. In a sample that contains 84.0 % of the **R enantiomer** and 16.0 % of the **S enantiomer**, the enantiomeric excess is calculated as follows:

**Calculation**: The enantiomeric excess is 84.0% (R) - 16.0% (S) = 68.0%

Therefore, the enantiomeric excess of the mixture is 68.0%.

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Which term describes this molecular shape?A. Trigonal pyramidal

B. Trigonal planar

C. Tetrahedral

D. Linear

**Answer: **Trigonal Pyrimidal

**Explanation: Just took test**

Calculate the pH of a solution prepared by adding 20.0 mL of 0.100 M HCl to 80.0 mL of a buffer that is comprised of 0.25 M C2H5NH2 and 0.25 M C2H5NH3Cl. Kb of C2H5NH2 = 9.5 x 10-4.

**Answer:**** The pH of resulting solution is 10.893**

**Explanation:**

**To calculate the number of moles for given molarity, we use the equation:**

**For ethylamine:**

Molarity of ethylamine solution = 0.25 M

Volume of solution = 80 mL

**Putting values in above equation, we get:**

**For HCl:**

Molarity of HCl = 0.100 M

Volume of solution = 20.0 mL

**Putting values in above equation, we get:**

**For :**

Molarity of solution = 0.25 M

Volume of solution = 80 mL

**Putting values in above equation, we get:**

**The chemical reaction for ethylamine and HCl follows the equation:**

__ Initial:__ 0.02 0.002 0.02

__ Final:__ 0.018 - 0.022

Volume of solution = 20.0 + 80.0 = 100 mL = 0.100 L **(Conversion factor: 1 L = 1000 mL)**

**To calculate the pOH of basic buffer, we use the equation given by Henderson Hasselbalch:**

**We are given:**

= negative logarithm of base dissociation constant of ethylamine =

pOH = ?

**Putting values in above equation, we get:**

**To calculate pH of the solution, we use the equation:**

**Hence, the pH of the solution is 10.893**

The **pH** of the solution is 10.9

Data;

- Volume of buffer = 80mL
- Volume of HCL = 20.0mL
- conc. of C2H5NH2 = 0.25M
- conc. of C2H5NH3Cl = 0.25
- Kb of C2H5NH2 = 9.5*10^-4

The **pH** of buffer can be calculated by using **Henderson-Hasselbalch's equation**

The initial moles of salt present is calculated as

The initial moles of base present is calculated as

On adding HCl the following reaction will occurs

This will lead to formation of extra moles of **salt** that is equal to moles of acid added and eventually lead to decrease in number of moles of base by equal measure.

Moles of HCl added is

Adding the value

Moles of salt present = 20 + 2 = 22mmoles

Subtracting the value

Moles of base left = 20-2 = 18mmoles

Now using **Henderson-Hasselbalch's equation** we can calculate the **pOH** of solution

The pOH of the base can be calculated as

Using the above, we can solve for the **pH** of the solution.

The **pH** of the solution is 10.9

Learn more on **pH** of a **solution** using** Henderson-Hasselbalch equation** here;

Which particles affect the stability in of the atom

The stability of an **atom** is affected by the balance between the electrons, **protons**, and **neutrons** in an atom.

A particle less than an atom is referred to as a subatomic particle. A subatomic particle can either be an elementary particle, which is not made of other particles, or a composite particle, which is composed of other particles, according to the Standard Model of particle physics.

Particles smaller than an atom are referred to as subatomic particles. The three primary subatomic particles present in an atom are **protons**, **neutrons**, and **electrons**.

Learn more about **sub-atomic particles **at: brainly.com/question/16847839

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balance protons and neutrons

For the reaction, calculate how many moles of the product form when 2.73 mol of h2 completely reacts. assume that there is more than enough of the other reactant. h2(g)+cl2(g)→2hcl(g)

For the calculation of number of moles of HClthat is produced by 2.73 moles of H₂.

Considering the reaction shown below:

H₂ + Cl₂------->2HCl

This can be seen from the reaction that 1 mole of H₂ produce=2 mole of HCl

So , 2.73 mole of H_{2} will produce= 2.73\times 2 mole of HCl

That is 2.73 mole of H_{2} will produce= 5.46 mole of HCl

So 5.46 mole of HCl will be produced by 2.73 mole of H_{2}

**Answer:**

**Explanation:**

Hello,

In this case, as both of the reactants are completely consumed, one infers that the following stoichiometric relationship leads to the produced moles of the product; hydrochloric acid:

It is important to notice that based on the undergoing chemical reaction, 1 mole of hydrogen is related with 2 moles of hydrochloric acid, that is why he product's moles doubles the hydrogen's moles.

Best regards.