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3 years ago

12. Compare and contrast hydrogen bonds and van der Waals interactions.

Chemistry

1 answer:

mrs_skeptik [129]3 years ago

4 0

Explanation:

Van der Waals interactions occur between any two or more molecules. They are caused by a fluctuation in electron density, as electrons are not actually fixed in a shell, but actually freely moving as a 'cloud of electron density'. This means that sometimes one end of a molecule can become more partially negatively charged as all electrons move to that side, and conversely it can attract the more partially positive end of a molecule (that has little electrons).

Hydrogen bonds only occur between molecules that contain oxygen, nitrogen and fluorine bonded to a hydrogen atom.

Hydrogen bonding is also the strongest intermolecular force there is, but not strong in comparison to ionic and covalent bonds. Therefore, hydrogen bonds are much stronger than Van der Waals forces. Hydrogen bonds only form if oxygen, nitrogen and fluorine are bonded to a hydrogen atom, as they have the greatest electronegativity differences (look at an electronegativity table), and when the overall molecule is polar (have unequal charges). This allows the molecule to be able to attract another molecule from one of the bonded atoms to a hydrogen atom.

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What scientist do that is the basis for their investigation

Tju [1.3M]

They come up with a hypothesis (question to investigate), then they work out what variables and what they will be measuring, keeping the same and changing in the experiment

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3 years ago

Read 2 more answers

A 996.9 g sample of ethanol undergoes a temperature change of -70.98 °C while releasing 62.9

Volgvan

Answer:

$c=3.71\ J/g^{\circ} C$

Explanation:

Given that,

Mass of sample, m = 996.9 g

The change in temperature of the sample, $\Delta T=-70.98^{\circ}C$

Heat produced, Q = 62.9 calories = 263173.6 J

The heat released by a sample due to change in temperature is given by :

$Q=mc\Delta T$

Where

c is the specific heat capacity

So,

$c=\dfrac{Q}{m\Delta T}\\\\c=\dfrac{263173.6}{996.9\times 70.98}\\\\c=3.71\ J/g^{\circ} C$

So, the specific heat of ethanol is equal to $3.71\ J/g^{\circ} C$ .

3 0

3 years ago

A 4.0 L container holds a sample of hydrogen gas at 306 K and 150 kPa. If the pressure increases to 300 kPa and the volume remai

riadik2000 [5.3K]

Answer:

612 K

Explanation:

From the question given above, the following data were obtained:

Initial temperature (T₁) = 306 K

Initial pressure (P₁) = 150 kPa

Final pressure (P₂) = 300 kPa

Volume = 4 L = constant

Final temperature (T₂) =?

Since the volume is constant, the final (i.e the new) temperature of the gas can be obtained as follow:

P₁ / T₁ = P₂ / T₂

150 / 306 = 300 / T₂

Cross multiply

150 × T₂ = 306 × 300

150 × T₂ = 91800

Divide both side by 150

T₂ = 91800 / 150

T₂ = 612 K

Thus, the new temperature of the gas is 612 K

4 0

3 years ago

A 200.-milliliter sample of CO2(g) is placed in a sealed, rigid cylinder with a movable piston at 296 K and 101.3 kPa. Determine

bagirrra123 [75]

Answer:

The final volume of the sample of gas $V_{2}$ = 0.000151 $m^{3}$

Explanation:

Initial volume $V_{1}$ = 200 ml = 0.0002 $m^{3}$

Initial temperature $T_{1}$ = 296 K

Initial pressure $P_{1}$ = 101.3 K pa

Final temperature $T_{2}$ = 336 K

Final pressure $P_{2}$ = K pa

Relation between P , V & T is given by

$P_{1} \frac{V_{1} }{T_{1} } = P_{2} \frac{V_{2} }{T_{2} }$

Put all the values in the above equation we get

$101.3 (\frac{0.0002}{296} )= 152 (\frac{V_{2} }{336} )$

$V_{2}$ = 0.000151 $m^{3}$

This is the final volume of the sample of gas.

4 0

4 years ago

How many water molecules are produced when 5.2g O2 are reacted

gtnhenbr [62]

Answer:

Total number of water molecules produced after the reaction is 1.956×10^22 molecules of water.

Explanation:

By the reaction

H2+ 1/2 O2 → H2O

Moles of O2 = 5.2\32

⇒1 mole of O2 produce 1 mole of H2O

1 mole O2 will produce 2 mole of H2O

Therefore, 5.2\32 mole will produce ${2}\times{\frac{5.2}\times{32}}$

⇒ Molecules of H2O will be

${2}\times{\frac{5.2}{32}}$ = $\frac{x}{{6.02}\times{10^23}}$

= 1.956×10^22 moleculesof H2O.

5 0

3 years ago