Question

What is the chemical formula of hydrogen chloride?
A: $HCl$
B: ${H_2}Cl$
C: $HC{l_2}$
D: $HCD$

Answer 1

Hint: Substances that have more than one atoms or elements bonded together are called molecules. A chemical formula of a compound shows the symbol of elements present in that compound. It also shows the ratio of the elements to one another.

Complete step by step solution:
We already know what compound and chemical formula is. Now we will discuss how this is made. To find the chemical formula of a compound firstly identify its cation, write its symbol and charge. Similarly identify anion, write down its symbol and charge. Then combine cation and anion such that as a whole compound is neutral. As we know cation is positively charged species and anion is negatively charged species. As the name suggests hydrogen chloride is made up of hydrogen and chlorine. Out of hydrogen and chlorine hydrogen is positively charged and chlorine is negatively charged (because it requires one electron to complete its octet. When it will gain an electron it will possess negative charge). Therefore cation is hydrogen and anion is chlorine. Symbol of hydrogen is $H$ and its charge is $ + 1$, Symbol of chlorine is $Cl$ and charge on it is $ - 1$. Therefore to make compound neutral one atom of chlorine and one atom of hydrogen will be needed. So, the formula of the compound will be $HCl$ . So answer of this question is option A i.e. $HCl$.

Note: To solve such questions write the symbol of cation on the left side and write its charge just below it. Similarly write the symbol of anion on the right side and its charge below it. Charge on the anion will be equal to the number of atoms of cation and charge of cation will be equal to the number of atoms of anion. Combining all these things we will get the chemical formula of the desired compound. Also remember to reduce the molecules to the smallest integer.