what mass of water will contain the same number of molecules as 8.0g of ferrous oxide [FeO]?
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Answers
Answer:
2g
Explanation:
Molar mass of FeO=72g
Molar mass of H2O=18g
Moles in 8g of FeO = 8/72 = 1/9
Mass of H2O with same number of molecules= (1/9)*18 = 2g
Given:
mass of FeO = 8g
To Find:
The number of molecules of FeO - N = number of molecules of water =?
mass of water - m =?
Solution:
Formula used:
- number of moles - n = mass - m / Molecular mass - M
- Also, n = number of molecules(N)/Avagadro number - Nₐ
- ∴ m/M = N/Nₐ
- Hence m = N/Nₐ × M
Applying the above formula to find the number of molecules in 8g of FeO
(Using the molecular mass of FeO = 56 + 16 = 72g and Nₐ = 6.032 × 10²³)
m/M = N/Nₐ
8/72 = N/6.023 × 10²³
N = 8/72 × 6.023 × 10²³
N = 6.023 × 10²³/9
N = 0.67 × 10²³ molecules of FeO = 0.67 × 10²³molecules of water
Applying the formula to find the mass of 0.67 × 10²³molecules of water
The Molecular mass of water - H₂O = 16 + 2 = 18g
m/M =N/Nₐ
m = N/Nₐ × M
m = 0.67 × 10²³/6.023 × 10²³ × 18
m = 0.11 × 18
m = 2g
Hence, the mass of water with 0.67 × 10²³molecules = 2g.