1) Data:
<span>initial decay rate, No =16,800 disintegrations/min
final decay rate, Nf = 10,860 disintegrations/min
t = 28.0 days
t half-life =?
2) Formulas
Radioactive disintegration =>
Nt = No * e ^ (-kt)
t half-life = ln (2) / k
3) Solution
From Nt = No * e^ (-kt) =>
Nt / No = e ^ (-kt)
=> -kt = ln (Nt / No)
=> kt = ln (No/Nt)
=> k = ln (No / Nt) / t
=> k = ln (16,800 / 10,860) / 28 days = 0.01558 days^ -1
From t half-life = ln(2) / k
t half-life = ln(2) / (0.01558 days^-1) = 44.5 days.
Answer: 44.5 days.
</span>
Answer:
[KHP] = 0.0428M
Explanation:
2 methods to calculate concentration after dilution
1. Use dilution equation
Molarity of concentrate (M₁) x Volume of Concentrate (V₁)
= Molarity of dilute (M₂) x Volume of dilute (V₂)
M₁ x V₁ = M₂ x V₂ => M₂ = M₁ x V₁ / V₂ = (1.07M)(10ml)/(250ml) = 0.0428M
2. Concentration Equation
moles KHPh = Molarity (M) x Volume (V) = 1.07M x 0.010L =0.0107 moles KHP
Concentration KHP = moles solute / volume of solution in Liters
= 0.0107 moles KHP / 0.25L = 0.0428M
There are 6 molecules of Mg3(PO4)2
6 × 3 = 18 Mg
6 × 4 × 2 = 48 O
From the calculations, the pH of the buffer is 3.1.
<h3>What is the pH of the buffer solution?</h3>
The Henderson-Hasselbach equation comes in handy when we deal with the pH of a buffer solution. From that equation;
pH = pKa + log[(salt/acid]
Amount of the salt = 25/1000 * 0.50 M = 0.0125 moles
Amount of the acid = 75/1000 * 1.00 M = 0.075 moles
Total volume = ( 25 + 75)/1000 = 0.1 L
Molarity of salt = 0.0125 moles/0.1 L = 0.125 M
Molarity of the acid = 0.075 moles/0.1 L = 0.75 M
Given that the pKa of lactic acid is 3.86
pH = 3.86 + log( 0.125/0.75)
pH = 3.1
Learn more about pH:brainly.com/question/5102027
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Answer:
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