Question

The energy required for the thermal decomposition of 16.8g of magnesium carbonate is 23.4kJ. Write a balanced symbol equation, including state symbols, for the reaction.

Answer 1

Answer:

$MgCO_{3}$ (s) ⇒ MgO (s) + $CO_{2}$ (g)

Explanation:

Decomposition means breakdown. Magnesium carbonate ($MgCO_{3}$) is a solid, and it thermally decomposes into magnesium oxide (MgO) - which is also a solid -  and carbon dioxide ($CO_{2}$ ) - which is a gas - .

The equation is already balanced hence why there are no coefficients (the coefficient is 1, so it's a 1:1:1 ratio, but we don't write the 1s).

As for knowing the state symbols, I guess you just have to memorize the states of the compounds/elements that are given to you in practice questions. Otherwise, the questions themselves will give you hints  - unlike the question here -.

Good luck, student!