Question

Write the chemical formula for each substance mentioned in the following word descriptions (use the front inside cover to find the symbols for the elements you do not know). (b) On treatment with hydrofluoric acid, silicon dioxide forms silicon tetrafluoride and water. (use the front inside cover to find the symbols for the elements you do not know). (c) Sulfur dioxide reacts with water to form sulfurous acid. (use the front inside cover to find the symbols for the elements you do not know). (d) The substance phosphorus trihydride, commonly called phosphine, is a toxic gas. (e) Perchloric acid reacts with cadmium to form cadmium(II) perchlorate.

Accepted Answer

Step 1: Identify the elements in the compound. In this case, the compound is phosphorus trihydride, which contains the elements phosphorus and hydrogen. Step 2: The prefix 'tri' in 'trihydride' indicates that there are three atoms of hydrogen for every atom of phosphorus. Step 3: Write the symbol for each element, followed by the number of atoms of that element in the compound. The symbol for phosphorus is 'P' and the symbol for hydrogen is 'H'. Step 4: The number of atoms is written as a subscript after the element symbol. Since there is one atom of phosphorus and three atoms of hydrogen, the chemical formula is written as P1H3. Step 5: If the subscript is 1, it is usually omitted. So, the final chemical formula for phosphorus trihydride, or phosphine, is PH3.