Answer:
4.419 g
Explanation:
55 years is 5.5 half lives
200 g * (1/2)^5.5 = 4.419 g
<h2>Natural Abundance for 10B is 19.60%</h2>
Explanation:
- The natural isotopic abundance of 10B is 19.60%.
- The natural isotopic abundance of 11B is 80.40%.
- The isotopic masses of boron are 10.0129 u and 11.009 u respectively.
For calculation of abundance of both the isotopes -
Supposing it was 50/50, the average mass would be 10.5, so to increase the mass we need a more percentage of 11.
Determining it as an equation -
10x + 11y= 10.8
x+y=1 (ratio)
10x + 10y = 10
By taking the denominator away from the numerator
we get;
y = 0.8
x + y = 1
∴ x = 0.2
To get percentages we need to multiply it by 100
So, the calculated abundance is 80% for 11 B and 20% 10 B.
Answer:
Mass of oxygen = 2.2 g
Explanation:
Given data:
Mass of benzoic acid= 8.20 g
Mass of oxygen= ?
Solution:
Molar mass of oxygen = 16×2 g/mol
Molar mass of C₆H₅COOH = 7×12 + 1×6 + 2×16
Molar mass of C₆H₅COOH = 84 + 6 + 32
Molar mass of C₆H₅COOH = 122g/mol
Mass of oxygen in 8.20 g of C₆H₅COOH :
Mass of oxygen = 32 g.mol⁻¹/122 g.mol⁻¹ × 8.20 g
Mass of oxygen = 2.2g
