Question

Ancient Romans built often out of bricks and mortar. A key ingredient in their mortar was quicklime (calcium oxide), which they produced by roasting limestone (calcium carbonate). 1. Write a balanced chemical equation, including physical state symbols, for the decomposition of solid calcium carbonate () into solid calcium oxide and gaseous carbon dioxide. 2. Suppose of carbon dioxide gas are produced by this reaction, at a temperature of and pressure of exactly . Calculate the mass of calcium carbonate that must have reacted. Be sure your answer has the correct number of significant digits.

Answer 1

The question has missing information. At part 1 it is "Write a balanced chemical equation, including physical state symbols, for the decomposition of solid calcium carbonate (CaCO3) into solid calcium oxide and gaseous carbon dioxide."

Part 2. "Suppose 19.0 L of carbon dioxide gas are produced by this reaction, at a temperature of 290.0°C and pressure of exactly 1 atm. Calculate the mass of calcium carbonate that must have reacted (...)"

Answer:

41.0 g

Explanation:

1. Calcium oxide has molecular formula CaO and carbon dioxide CO₂, thus, the reaction will be:

CaCO₃(s) → CaO(s) + CO₂(g)

The equation is already balanced because there's the same number of each element on both sides.

2. First, let's calculate the number of moles of CO₂ produced by the ideal gas law:

PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant (0.082 atm.L/mol.K), and T is the temperature (290°C = 273 = 563 K).

1*19 = n*0.082*563

46.166n = 19

n = 0.4116 mol

By the stoichiometry of the reaction:

1 mol of CaCO₃ ------ 1 mol of CO₂

x ----- 0.4116 mol

By a simple direct three rule:

x = 0.4116 mol of CaCO₃.

The molar mass of the calcium carbonate is 100 g/mol, thus the mass (m) is the number of moles multiplied by it:

m = 0.4116*100

m = 41.16 g = 41.0 g