Answer:
An exothermic reaction is a chemical reaction that releases energy by light or heat. Endothermic reaction is a chemical reaction that absorbs energy or heat from its surroundings
Explanation:
PH + pOH = 14
pH + 0.253 = 14
pH = 14 - 0.253
pH = 13.747
[ H+] = 10 ^ -pH
[ H+ ] = 10 ^- 13.747
[ H+ ] = 1.790x10⁻¹⁴ M
hope this helps!
Answer:
thank you have a great April fool weekend
Given that,
The concentration of
TRIS = 0.30 M
The concentration of
TRIS+ = 0.60 M
Kb = 1.2 x 10^-6
pKb = -log Kb = - log
(1.2 x 10^-6) = 5.920
Now, by using the
Hendersonn equation,
pH = pKa + log
TRIS+/TRIS = 5.920 + log (0.60/0.30) = 6.221
<span>pOH=14-pH=14-6.221 =
7.779</span>
For this problem we can use half-life formula and radioactive decay formula.
Half-life formula,
t1/2 = ln 2 / λ
where, t1/2 is half-life and λ is radioactive decay constant.
t1/2 = 8.04 days
Hence,
8.04 days = ln 2 / λ
λ = ln 2 / 8.04 days
Radioactive decay law,
Nt = No e∧(-λt)
where, Nt is amount of compound at t time, No is amount of compound at t = 0 time, t is time taken to decay and λ is radioactive decay constant.
Nt = ?
No = 1.53 mg
λ = ln 2 / 8.04 days = 0.693 / 8.04 days
t = 13.0 days
By substituting,
Nt = 1.53 mg e∧((-0.693/8.04 days) x 13.0 days))
Nt = 0.4989 mg = 0.0.499 mg
Hence, mass of remaining sample after 13.0 days = 0.499 mg
The answer is "e"
