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3 years ago

Hydrogen bond notes

Chemistry

1 answer:

Andrews [41]3 years ago

4 0

Answer:

a weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.

Explanation:

A hydrogen bond is a partial intermolecular bonding interaction between a lone pair on an electron rich donor atom, particularly the second-row elements nitrogen, oxygen, or fluorine, and the antibonding molecular orbital of a bond between hydrogen and a more electronegative atom or group.

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What mass of potassium hypochlorite (FW-90.6 g/mol) must be added to 4.50 x 10 mL of water to give a solution with pH 10.20? [Ka

marta [7]

Answer : The mass of potassium hypochlorite is, 4.1 grams.

Explanation : Given,

pH = 10.20

Volume of water = $4.50\times 10^2ml=0.45L$

The decomposition of KClO will be :

$KClO\rightarrow K^++ClO^-$

Now the further reaction with water $(H_2O)$ to give,

$ClO^-+H_2O\rightarrow HClO+OH^-$

First we have to calculate the pOH.

$pH+pOH=14\\\\pOH=14-pH\\\\pOH=14-10.20=3.8$

Now we have to calculate the $OH^-$ concentration.

$pOH=-\log [OH^-]$

$3.8=-\log [OH^-]$

$[OH^-]=1.58\times 10^{-4}M$

Now we have to calculate the base dissociation constant.

Formula used : $K_b=\frac{K_w}{K_a}$

Now put all the given values in this formula, we get :

$K_b=\frac{1.0\times 10^{-14}}{4.0\times 10^{-8}}=2.5\times 10^{-7}$

Now we have to calculate the concentration of $ClO^-$ .

The equilibrium constant expression of the reaction is:

$K_b=\frac{[OH^-][HClO]}{[ClO^-]}$

As we know that, $[OH^-]=[HClO]=1.58\times 10^{-4}M$

$2.5\times 10^{-7}=\frac{(1.58\times 10^{-4})^2}{[ClO^-]}$

$[ClO^-]=0.0999M$

Now we have to calculate the moles of $ClO^-$ .

$\text{Moles of }ClO^-=\text{Molarity of }ClO^-\times \text{Volume of solution}$

$\text{Moles of }ClO^-=0.0999mole/L\times 0.45L=0.0449mole$

As we know that, the number of moles of $ClO^-$ are equal to the number of moles of KClO.

So, the number of moles of KClO = 0.0449 mole

Now we have to calculate the mass of KClO.

$\text{Mass of }KClO=\text{Moles of }KClO\times \text{Molar mass of }KClO$

$\text{Mass of }KClO=0.0449mole\times 90.6g/mole=4.07g\approx 4.1g$

Therefore, the mass of potassium hypochlorite is, 4.1 grams.

6 0

3 years ago

At the top of a hill, an athlete on a skateboard has X joules of mechanical energy. How much mechanical energy will she have at

ExtremeBDS [4]

If an athlete has X joules of mechanical energy at the top of the hill, he will have the same X amount of energy at the bottom of the hill.

<h3>What is mechanical energy?</h3>

Mechanical energy is the addition of kinetic and potential energy. It can be either kinetic or potential energy.

It is the energy possessed by the position or the motion of the body.

It is the energy present to perform any work.

So, the athlete will have X joule of energy at the top and bottom of the hill.

Thus, the correct option is a, X joules.

Learn more about mechanical energy

brainly.com/question/20030300

5 0

2 years ago

If a gas at 25.0 °C occupies 3.60 liters at a pressure of 1.00 atm, what will be its volume at a pressure of 2.50 atm?

Greeley [361]

Answer:

1.44 L

Explanation:

Since 25 is constant it is no use. Now, rearrange the gas formula. You should get...

P1V1/T2=P2V2T1

Next, rearrange to fit the problem. You should get...

V2=P1V1/P2

Fill in our values and solve. You should get 1.44 L

We can check this by knowing that P and V at constant T have an inverse relationship. Hence, this is correct.

- Hope that helps! Please let me know if you need further explanation.

8 0

3 years ago

A piece of unknown metal weighs 348g. When the metal piece absorbs 6.64kj of heat , its temperature increases from 24.4C to 43.6

Morgarella [4.7K]

Answer:

This metal could be the aluminium with a specific heat of $H = 993 \frac{J}{kgC}$

Explanation:

A pie of unknown metal presents a mass (M) of 348 g. This metal is heated using energy (E) of 6.64 kJ and the temperature increases from T1 =24.4 to T2 =43.6°C. We can calculate the specific heat (H) of this metal as follows

$H = \frac{E}{M*(T2-T1)}$

We can replace previously presented data in this equation. After simplifying and converting to adequated units, we found that

$H = \frac{6640 J}{0.348 Kg*(43.6-24.4) C} =\frac{6640 J}{6.686 KgC}$

Finally, the specific heat of this metal is

$H = 993 \frac{J}{kgC}$

The aluminium could be the metal, its specific heat is similar to that found in this problem.

Finally, we can conclude that this metal could be the aluminium with a specific heat of $H = 993 \frac{J}{kgC}$

7 0

3 years ago

consider the substance:carbon dioxide, gold, bronze, alcohol, iron, and, oxygen.from the list , select the substances that :(1)

lbvjy [14]

Answer:

Oxygen

Explanation:

· Air decolorization makes use of chromophores’ instability on oxygen to decolorize the oil by air-oxidizing pigments. For example, the carotenoid and chlorophyll in the oil are very unstable because of their structure, which is easy to be discolored under the action of oxygen. However, air decolorization leads to thermal oxidation of the oil, too.

5 0

3 years ago

Hydrogen bond notes​

Hydrogen bond notes