Question

При нагревании навески известняка массой 35 г выделился газ объем(н.у.) которого составил 6.7 дм в кубе .Расчитайте массовую долю карбоната кальция в образце известняка

Answer 1

6,7 дм в куб / 22,4 = 0,3 моль
0,3 моль * 100 г/моль = 30 г карбоната кальция
30*100/35 = 85,71℅

Answer 2

Calculation of the Mass Fraction of Calcium Carbonate in Limestone

To calculate the mass fraction of calcium carbonate in the limestone sample, we need to use the information provided about the mass of limestone and the volume of gas released during heating.

Given: - Mass of limestone = 35 g - Volume of gas released (at standard temperature and pressure) = 6.7 dm³

To calculate the mass fraction of calcium carbonate, we can use the following steps:

Step 1: Calculate the molar volume of the gas released. The molar volume of a gas at standard temperature and pressure (STP) is 22.4 dm³/mol. We can use this information to calculate the number of moles of gas released.

Molar volume of gas at STP = 22.4 dm³/mol Volume of gas released = 6.7 dm³

Number of moles of gas released = Volume of gas released / Molar volume of gas at STP

Step 2: Calculate the molar mass of calcium carbonate (CaCO₃). The molar mass of calcium carbonate can be calculated by summing the atomic masses of its constituent elements: calcium (Ca), carbon (C), and oxygen (O).

Molar mass of CaCO₃ = (Atomic mass of Ca) + (Atomic mass of C) + 3 * (Atomic mass of O)

Step 3: Calculate the number of moles of calcium carbonate. Using the number of moles of gas released and the stoichiometry of the reaction, we can calculate the number of moles of calcium carbonate.

Number of moles of CaCO₃ = Number of moles of gas released / 2

Step 4: Calculate the mass of calcium carbonate. Using the number of moles of calcium carbonate and its molar mass, we can calculate the mass of calcium carbonate.

Mass of CaCO₃ = Number of moles of CaCO₃ * Molar mass of CaCO₃

Step 5: Calculate the mass fraction of calcium carbonate. Finally, we can calculate the mass fraction of calcium carbonate by dividing the mass of calcium carbonate by the mass of the limestone sample and multiplying by 100%.

Mass fraction of CaCO₃ = (Mass of CaCO₃ / Mass of limestone) * 100%

Let's perform the calculations:

Step 1: Number of moles of gas released = 6.7 dm³ / 22.4 dm³/mol

Step 2: Molar mass of CaCO₃ = (40.08 g/mol) + (12.01 g/mol) + 3 * (16.00 g/mol)

Step 3: Number of moles of CaCO₃ = (Number of moles of gas released) / 2

Step 4: Mass of CaCO₃ = (Number of moles of CaCO₃) * (Molar mass of CaCO₃)

Step 5: Mass fraction of CaCO₃ = (Mass of CaCO₃ / Mass of limestone) * 100%

Please note that the atomic masses used in the calculations are approximate values and may vary slightly depending on the source.