when writing chemical equations,
for example, next to oxygen I have to write (g) for gas and next to other different chemicals I have to write (aq) for aqueous.
What do I write next to H2O?
(l) Isn't water either liquid, solid, or gas, depending on the temperature?
Next to H2O, you would write (l) to indicate that it is in the liquid state. The (l) signifies that water is in its liquid form. Here's how you can determine the state of a substance and annotate it correctly in a chemical equation:
1. Gases: Gases are indicated by (g) in parentheses. This means the substance is in a gaseous state at normal atmospheric conditions. Examples include oxygen (O2), carbon dioxide (CO2), and hydrogen (H2).
2. Liquids: Liquids are denoted by (l) in parentheses. This indicates that the substance is a liquid at normal atmospheric conditions. Water (H2O), ethanol (C2H5OH), and bromine (Br2) are examples of liquid substances.
3. Solids: Solids do not require any additional notation. If a substance is normally solid at room temperature, it is typically written without any indication. Examples include salt (NaCl), sugar (C12H22O11), and iron (Fe).
4. Aqueous solutions: Aqueous solutions, or substances dissolved in water, are specified by writing (aq) in parentheses. This shows that the chemical is in dissolved form in water. Examples include sodium chloride solution (NaCl(aq)), sulfuric acid solution (H2SO4(aq)), and potassium hydroxide solution (KOH(aq)).
Remember to consider the physical state of each substance when writing a balanced chemical equation, as it provides important information about the reactants and products involved.