Question

Сколько молекул содержится в 20 граммах оксида кальция (CaO)?

Answer 1

Дано: m(CaO) = 20 г
Na = 6,02*10²³ моль⁻¹
M(CaO) = 56 г/моль

Найти: N(CaO) - ?

Решение: n = m/M = N/Na
N = m*Na/M = 20*6,02*10²³/56 = 2,15*10²³

Ответ: N(CaO) = 2,15*10²³ молекул

Answer 2

Calculation of the Number of Molecules in 20 grams of Calcium Oxide (CaO)

To calculate the number of molecules in 20 grams of calcium oxide (CaO), we need to use the concept of moles and Avogadro's number.

1. Find the molar mass of calcium oxide (CaO): - The molar mass of calcium (Ca) is approximately 40.08 grams per mole. - The molar mass of oxygen (O) is approximately 16.00 grams per mole. - The molar mass of calcium oxide (CaO) is the sum of the molar masses of calcium and oxygen: 40.08 + 16.00 = 56.08 grams per mole.

2. Calculate the number of moles in 20 grams of calcium oxide: - Divide the mass of calcium oxide (20 grams) by its molar mass (56.08 grams per mole): 20 grams / 56.08 grams per mole ≈ 0.356 moles.

3. Use Avogadro's number to calculate the number of molecules: - Avogadro's number is approximately 6.022 × 10^23 molecules per mole. - Multiply the number of moles (0.356 moles) by Avogadro's number: 0.356 moles × 6.022 × 10^23 molecules per mole ≈ 2.144 × 10^23 molecules.

Therefore, there are approximately 2.144 × 10^23 molecules in 20 grams of calcium oxide (CaO).

Please note that the calculations provided are based on the given molar masses and Avogadro's number.