Question

Please answer and explain. Thank you. (Biochemistry)

The water molecule is unique among the hydrides among the second period elements, C,N, O and F. CH4 and HF are all gases. Water alone is not a gas at room temperature. Explain why this molecule of similar mass to the others is a liquid.

The purification technique of electrophoresis relies on two properties of proteins. Name these properties and how biochemists take advantage of them in this method.

Draw the following peptide and indicate whether it is polar or non-polar. Ala-Gly-Val-Ile-Phe-Ile-Val-. How many chiral centers are in the peptide?

Answer 1

Because they differ in the type and strength of intermolecular forces their molecules exhibit.The state in which a compound can be found at room temperature and standard pressure depends on what type of intermolecular forces of attraction its molecules exhibit.

More precisely, it depends on the strength of these intermolecular forces. In your particular case, stronger intermolecular forces are associated with liquids and weaker intermolecular forces are associated with gases.

Borane, BH₃ and methane CH₄, are gases at room temperature because they are nonpolar molecules which means that they only exhibit weak London dispersion forces.

A more interesting comparison is between water H₂O and hydrogen fluoride HF on one side and ammonia NH₃ on the other.

It would be worth specifying that hydrogen fluoride boils at about 20⁰C, so if by room temperature you mean 25⁰C, then hydrogen fluoride will actually be a gas.So let's asssume that you're working at a temperature of 15⁰C.

All three molecules exhibit strong hydrogen bonding, a special type of dipole-dipole interactions that arise when hydrogen is directly bonded to one of the three most electronegative atoms - nitrogen, oxygen, and fluorine

Ammonia a gas and room temperature while water and hydrogen fluoride are liquids Because One reason for why that happens is because the difference in electronegativitybetween hydrogen and nitrogen is not as pronounced as the difference in electronegativity between hydrogen and oxygen or hydrogen and fluorine.

Another important reason is that these molecules have a different number of lone pairs present on the more electronegative atom.

In water's case you have two partial positive hydrogen atoms and two lone pairs of electrons on the oxygen atom, which means that each water molecule can form hydrogen bonds with four other water molecules.