Answer:
Explanation:
1) Given data:
Number of moles of lead = 4.3×10⁻³ mol
Mass of lead = ?
Solution:
Mass = number of moles × molar mass
Molar mass of lead = 207.2 g/mol
Mass = 4.3×10⁻³ mol × 207.2 g/mol
Mass = 890.96 g
2) Given data:
Number of atoms of antimony = 3.8×10²² atoms
Mass of antimony = ?
Solution:
1 mole contain 6.022 ×10²³ atoms
3.8×10²² atoms × 1 mol / 6.022 ×10²³ atoms
0.63×10⁻¹ mol
0.063 mol
Mass = number of moles × molar mass
Molar mass of lead = 121.76 g/mol
Mass = 0.063 mol × 121.76 g/mol
Mass = 7.67 g
3) Given data:
Mass of tungsten = 15.5 Kg (15.5 kg × 1000 g/ 1kg = 15500 g)
Number of atoms = ?
Solution:
Number of moles of tungsten:
Number of moles = mass/molar mass
Number of moles = 15500 g / 183.84 g/mol
Number of moles = 84.3 mol
1 mole contain 6.022 ×10²³ atoms
84.3 mol × 6.022 ×10²³ atoms / 1mol
507.65 ×10²³ atoms
The half-life of polonium-210, given that it decays from 98.3 micrograms to 12.3 micrograms in 414 days is 138 days
<h3>How to determine the number of half-lives </h3>
- Original amount (N₀) = 98.3 micrograms
- Amount remaining (N) = 12.3 micrograms
- Number of half-lives (n) =?
2ⁿ = N₀ / N
2ⁿ = 98.3 / 12.3
2ⁿ = 8
2ⁿ = 2³
n = 3
<h3>How to determine the half life </h3>
- Number of half-lives (n) = 3
- Time (t) = 414 days
- Half-life (t½) = ?
t½ = t / n
t½ = 414 / 3
t½ = 138 days
Learn more about half life:
brainly.com/question/26374513
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