What type of bond is formed between hydrogen and nitrogen in ammonia (NH3)? A. polar covalent B. ionic C. nonpolar covalent D. metallic

A. Polar covalent  

Explanation:

The polarity of a bond depends on the electronegativity difference (ΔEN) between the bonded atoms.

If the electronegativity difference between the atoms is between 0.4 and 1.7, the bond is polar covalent.

For an N-H bond, ΔEN = |3.04-2.20| = 0.84

So, the bond is polar covalent.

B is wrong. A bond is ionic only if ΔEN > 1.6.

C is wrong. A bond is nonpolar only if ΔEN < 0.4.

D is wrong. N and H are not metals.

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%