How many oxygen atoms are in 2.30 g of quartz?
2 answers:
Answer:
4.61 * 10²² oxygen atoms
Explanation:
- Quartz is the common name of a silicon mineral, SiO₂.
- To solve the problem, we need to calculate the molar mass (MM) of quartz:
MM = AtomicMass of Si + 2 * AtomicMass of O
MM = 28.08 + 2 * 16
MM = 60.08 g/mol
- Then we can calculate how many moles of quartz are in 2.30 g:
2.30 g * = 0.0383 mol
- Then we use <em>Avogadro's number </em>calculate the number of oxygen atoms in 0.0383 mol of SiO₂, keeping in mind the number of O per quartz molecule:
0.0383 mol SiO₂ * = 4.61 * 10²² atoms of O
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Answer:
1.635 M
Explanation:
Given:
10 mL of 20 volumes Hydrogen Peroxide
Here,
20 volumes of Hydrogen Peroxide means that on decomposition of 1 mL of H₂O₂ 20 mL of O₂ is obtained
also,
means 1 dm³ of H₂O₂ solution produces 20 dm³ oxygen
Now,
at 298K and 1 atm
20 dm³ oxygen = moles
or
= 0.817 moles
also,
2H₂O₂ → 2H₂O + O₂
thus,
1 dm³ of solution must contain 2 × moles of O₂ as moles of H₂O₂
thus,
Number of moles of H₂O₂ = 2 × 0.817
or
Number of moles of H₂O₂ = 1.635 moles
Hence,
For 20 volume hydrogen peroxide is 1.635 M