Answer:
12.50g
Explanation:
T½ = 2.5years
No = 100g
N = ?
Time (T) = 7.5 years
To solve this question, we'll have to find the disintegration constant λ first
T½ = In2 / λ
T½ = 0.693 / λ
λ = 0.693 / 2.5
λ = 0.2772
In(N/No) = -λt
N = No* e^-λt
N = 100 * e^-(0.2772*7.5)
N = 100*e^-2.079
N = 100 * 0.125
N = 12.50g
The sample remaining after 7.5 years is 12.50g
HA ⇄ H⁺ + A⁻
so:
![\frac{[H^+][A^-]}{[HA]} = 1.5 x 10^{-5}](https://tex.z-dn.net/?f=%20%5Cfrac%7B%5BH%5E%2B%5D%5BA%5E-%5D%7D%7B%5BHA%5D%7D%20%3D%201.5%20x%2010%5E%7B-5%7D%20%20)
and now:
= 1.5 x 10⁻⁵
x is considered very small compared to 0.15
x² = 2.25 x 10⁻⁶
x = 1.5 x 10⁻³
So [H⁺] = 1.5 x 10⁻³
pH = - log [H⁺] = - log (1.5 x 10⁻³) = 2.83
Answer:
39.2 L at STP
Explanation:
Convert the grams to moles first by dividing 56.0 by the molar mass of O2 (32.0) then convert to volume by multiplying by 22.4.
= 39.2 L
The answer to this question is A- evaporation
Balanced chemical reaction: 2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g).
KOH is inorganic compound p<span>otassium hydroxide, a strong base.
H</span>₂ is hydrogen gas.
In balanced chemical reaction number of atoms on both side of chemical reaction must be same. There are two potassium atoms, four hydrogen atoms and two oxygen atoms on both side of reaction.
