# Calculate the mass of CaO that is formed during the decomposition of CaCO3 weighing 70 grams.

Let’s compose the reaction equation for the decomposition of calcium carbonate:
CaCO3 = CaO + CO2;

The relative atomic mass of calcium is 40 g / mol; carbon is equal to 12 g / mol; oxygen is 16 g / mol. Find the molecular weight of calcium carbonate:
40 + 12 + 16 * 3 = 100 g / mol;

Let’s find the amount of substance in calcium carbonate:
70/100 = 0.7 mol:

The amount of substance in calcium oxide is 0.7 mol, since there are the same coefficients in front of CaO and in front of CaCO3. The molecular weight of calcium oxide is 56 g / mol. Find the mass of calcium oxide:
56 * 0.7 = 39.2 grams;

Answer: The mass of calcium oxide is 39.2 grams. One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.