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3 years ago

Explain, in terms of intermolecular forces, why ammonia has a higher boiling point than the other compounds in the ta

1 answer:

7 0

Answer is: ammonia has a higher boiling point because it has stronger intermolecular forces.

Intermolecular forces are the forces between molecules. The stronger are intermolecular forces, the higher is boiling point of compound, because more energy is needed to break interaction between molecules.
There are several types of intermolecular forces: hydrogen bonding, ion-induced dipole forces, ion-dipole forces andvan der Waals forces.

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What is the mass of a cube of aluminum that is 4.0 cm on each edge? The density of aluminum is 2.7 g/cm3.

Y_Kistochka [10]

Mass will be 172.8 gram only

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3 years ago

Starting with 250 mL of a 0.250 M solution of HBr; a) Calculate the initial pH of the solution.b) Calculate the pH after adding

maxonik [38]

Answer:

pH = 0.602

pH = 1.5

pH = 7

pH = 12.1

Explanation:

a ) To calculate the pH, use the following equation:

pH = -log [H+]

Hbr is a strong acid, so the [H+] concentration can be calculated as follow:

[HBr] = 0.250 M

As acid Hbr:

Hbr = H+ + Br-

As strong acid HBr dissociates at all, so

[HBr] = [H+] = 0.250 M

So the pH:

pH = -log [0.250 M] = 0.602

b) Calculate the pH after adding 250 mL of 0.125M NaOH

In this point, the reactions starts:

HBr + NaOH = H2O + NaBr

- First, we gonna find the mol of each reactant:

HBr:

mol = [M] × L

mol = 0.250 M × 0.250 L

mol = 0.0625 mol HBr

NaOH:

mol = [M] × L

mol = 0.125 M × 0.250L

mol = 0.03125 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.0625 mol HBr – 0.03125 mol HBr = 0.03125 mol HBr

These are the moles free in the solution, and we going to use them to calculate the pH:

pH = -log [ H]

pH = - log [ 0.03125 ] = 1.5

c) Calculate the pH after adding 500 mL of 0.125M NaOH

NaOH:

mol = [M] × L

mol = 0.125 M × 0.500L

mol = 0.0625 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.0625 mol HBr – 0.0625 mol HBr = 0 HBr

pH = 7

d) Calculate the pH after adding 600 mL of 0.125M NaOH.

NaOH:

mol = [M] × L

mol = 0.125 M × 0.600L

mol = 0.075 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.075 mol NaOH – 0.0625 mol NaOH = 00125 NaOH

These are the moles free in the solution, and we going to use them to calculate the pH:

pOH = -log [ OH]

pOH = - log [ 0.0125 ] = 1.90

pH + pOH = 14

pH = 14- pOH = 14 – 1.90 = 12.1

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3 years ago

Which element is needed for a. Bone and teeth formation. b. Treatment of water.

expeople1 [14]

Bone and teeth formation
Treatment of water

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denpristay [2]

Answer:

Explanation:

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Rank the ions in each set in order of increasing size, and explain your ranking:

Paha777 [63]

Explanation:

Lithium, sodium and potassium are all group 1A elements and when we move down a group then there occurs an increase in atomic size of the elements. As lithium is the smallest and potassium being the largest so, when each of them will lose an electron and obtain a positive charge then size of lithium will further decrease.

Therefore, ions are ranked according to their increase in size as follows.

$Li^{+} < Na^{+} < K^{+}$

When an atom tends to gain electrons then it acquires a negative charge. This means that size of the atom increases.

So, more is the negative charge present on an atom more will be its atomic size. Therefore, correct order of increasing size for $Se^{2-}, Rb^{+}, Br$ is as follows.

$Br < Rb^{+} < Se^{2-}$

Similarly, order of increasing size of $O^{2-}, F^{-}, N^{3-}$ is as follows.

$F^{-} < O^{2-} < N^{3-}$

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3 years ago