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3 years ago

Paleontologists have discovered several ancestors of the modern horse.

Chemistry

2 answers:

ExtremeBDS [4]3 years ago

8 0

Answer:

hyracotherium

Explanation:

..........

Dahasolnce [82]3 years ago

5 0

Answer:

hyracotherium

Explanation:

they are the oldest to date record of a horse

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Photosynthesis in a plant is an example of which characteristic of living things?

lutik1710 [3]

Answer:

<h2>4. Ability to obtain and use energy</h2>

4 0

3 years ago

When a solution forms, what interactions between particles are involved? Which are exothermic? Which are endothermic?

Blizzard [7]

Answer:

Explanation:

There are three types of interactions involved between the particles when solution are formed.

1 : Solute - solute interaction:

2 : Solute - solvent interaction:

3 : Solvent - solvent interaction:

1 : Solute - solute interaction:

It is the inter-molecular attraction between the solute particles.

2 : Solute - solvent interaction:

It involve the inter-molecular attraction between solvent and solute particles.

3 : Solvent - solvent interaction:

It involve the intermolecular attraction between solvent particles.

Solutions are formed if the intermolecular attraction between solute particles are similar to the attraction between solvent particles.

Exothermic process:

The process will exothermic when solute solvent bonds are formed with the release of energy and energy required to brake the solute-solute particles and solvent solvent particles are less.

Endothermic process:

The process will be endothermic when energy required to break the solute-solute particles and solvent solvent particles are higher than energy released when solute solvent bonds are formed .

6 0

3 years ago

Calculate the activity coefficients for the following conditions:

uysha [10]

Answer:

For a: The activity coefficient of copper ions is 0.676

For b: The activity coefficient of potassium ions is 0.851

For c: The activity coefficient of potassium ions is 0.794

Explanation:

To calculate the activity coefficient of an ion, we use the equation given by Debye and Huckel, which is:

$-\log\gamma_i=\frac{0.51\times Z_i^2\times \sqrt{\mu}}{1+(3.3\times \alpha _i\times \sqrt{\mu})}$ ........(1)

where,

$\gamma_i$ = activity coefficient of ion

$Z_i$ = charge of the ion

$\mu$ = ionic strength of solution

$\alpha _i$ = diameter of the ion in nm

To calculate the ionic strength, we use the equation:

$\mu=\frac{1}{2}\sum_{i=1}^n(C_iZ_i^2)$ ......(2)

where,

$C_i$ = concentration of i-th ions

$Z_i$ = charge of i-th ions

For a:

We are given:

0.01 M NaCl solution:

Calculating the ionic strength by using equation 2:

$C_{Na^+}=0.01M\\Z_{Na^+}=+1\\C_{Cl^-}=0.01M\\Z_{Cl^-}=-1$

Putting values in equation 2, we get:

$\mu=\frac{1}{2}[(0.01\times (+1)^2)+(0.01\times (-1)^2)]\\\\\mu=0.01M$

Now, calculating the activity coefficient of $Cu^{2+}$ ion in the solution by using equation 1:

$Z_{Cu^{2+}}=2+\\\alpha_{Cu^{2+}}=0.6\text{ (known)}\\\mu=0.01M$

Putting values in equation 1, we get:

$-\log\gamma_{Cu^{2+}}=\frac{0.51\times (+2)^2\times \sqrt{0.01}}{1+(3.3\times 0.6\times \sqrt{0.01})}\\\\-\log\gamma_{Cu^{2+}}=0.17\\\\\gamma_{Cu^{2+}}=10^{-0.17}\\\\\gamma_{Cu^{2+}}=0.676$

Hence, the activity coefficient of copper ions is 0.676

For b:

We are given:

0.025 M HCl solution:

Calculating the ionic strength by using equation 2:

$C_{H^+}=0.025M\\Z_{H^+}=+1\\C_{Cl^-}=0.025M\\Z_{Cl^-}=-1$

Putting values in equation 2, we get:

$\mu=\frac{1}{2}[(0.025\times (+1)^2)+(0.025\times (-1)^2)]\\\\\mu=0.025M$

Now, calculating the activity coefficient of $K^{+}$ ion in the solution by using equation 1:

$Z_{K^{+}}=+1\\\alpha_{K^{+}}=0.3\text{ (known)}\\\mu=0.025M$

Putting values in equation 1, we get:

$-\log\gamma_{K^{+}}=\frac{0.51\times (+1)^2\times \sqrt{0.025}}{1+(3.3\times 0.3\times \sqrt{0.025})}\\\\-\log\gamma_{K^{+}}=0.070\\\\\gamma_{K^{+}}=10^{-0.070}\\\\\gamma_{K^{+}}=0.851$

Hence, the activity coefficient of potassium ions is 0.851

For c:

We are given:

0.02 M $K_2SO_4$ solution:

Calculating the ionic strength by using equation 2:

$C_{K^+}=(2\times 0.02)=0.04M\\Z_{K^+}=+1\\C_{SO_4^{2-}}=0.02M\\Z_{SO_4^{2-}}=-2$

Putting values in equation 2, we get:

$\mu=\frac{1}{2}[(0.04\times (+1)^2)+(0.02\times (-2)^2)]\\\\\mu=0.06M$

Now, calculating the activity coefficient of $K^{+}$ ion in the solution by using equation 1:

$Z_{K^{+}}=+1\\\alpha_{K^{+}}=0.3\text{ (known)}\\\mu=0.06M$

Putting values in equation 1, we get:

$-\log\gamma_{K^{+}}=\frac{0.51\times (+1)^2\times \sqrt{0.06}}{1+(3.3\times 0.3\times \sqrt{0.06})}\\\\-\log\gamma_{K^{+}}=0.1\\\\\gamma_{K^{+}}=10^{-0.1}\\\\\gamma_{K^{+}}=0.794$

Hence, the activity coefficient of potassium ions is 0.794

6 0

3 years ago

What is the intermolecular force of NH3

Dominik [7]

ANSWER:
London dispersion and hydrogen bonds.

EXPLANATION :
Every molecule experiences London dispersion as an intermolecular force.since the ammonia ion has hydrogen atoms bonded to nitrogen,a very electronegative atom,the molecule is also polar since the nitrogen atom more strongly pulls on the electrons from the hydrogen atoms than the hydrogens themselves do.

This effect is similar to that water,where the oxygen pulls the electrons of the hydrogen atoms with a greater magnitude,resulting in the oxygen having a partial negative charge and the hydrogens having a partial positive charge relative to each other.

This polarity shows that the molecule has dipole-dipole intermolecular forces but since the polarity is from a result of highly electronegative atoms (such as nitrogen,oxygen,fluorine) and hydrogen atoms actually bonded to them,the polarity is categorized in it's own intermolecular force called a hydrogen bond.

I HOPE IT HELPS:)

3 0

3 years ago

A scientist is combining two gray elements. He thinks he will get a gray compounds. Use what you learned in this lesson to expla

adelina 88 [10]

Answer:

Explanation:

Depending on the elements that are being combined, a chemical reaction could occur and cause a change of color to take place if the elements reacts to the other one.

3 0

2 years ago