Question

Write the formula of a compound of hydrogen with (a) sulfur. (b) nitrogen, which is a liquid at \(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\). (c) phosphorus, which is a poisonous gas at \(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm} .\)

Short answer

Answer: The formulas of the compounds are hydrogen sulfide (H2S), hydrazine (N2H4), and phosphine (PH3).

Step-by-step solution

Compound with Sulfur

Hydrogen and sulfur form a compound known as hydrogen sulfide (H2S). It is formed from hydrogen atoms with a valency of 1 and sulfur atoms with a valency of 2. So, we can write the formula as H2S.

Compound with Nitrogen (liquid at \(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\))

Two compounds are formed by hydrogen and nitrogen: ammonia (NH3) and hydrazine (N2H4). Ammonia is a gas at room temperature, so the compound of interest is hydrazine, which exists as a colorless liquid at \(25^{\circ} \mathrm{C}\) and 1 atm pressure. So, the formula of the compound with nitrogen is N2H4.

Compound with Phosphorus (poisonous gas at \(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\))

Hydrogen and phosphorus form three different compounds: phosphine (PH3), diphosphine (P2H4), and triphosphine (P3H5). Among these compounds, phosphine is a poisonous gas at room temperature. The other two compounds are less toxic and not gaseous at room temperature. So, the formula of the compound with phosphorus is PH3.