Answer:
1.146 x 10⁴ year.
Explanation:
- The decay of carbon-14 is a first order reaction.
- The rate constant of the reaction (k) in a first order reaction = ln (2)/half-life = 0.693/(5730 year) = 1.21 x 10⁻⁴ year⁻¹.
- The integration law of a first order reaction is:
<em>kt = ln [A₀]/[A]</em>
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k is the rate constant = 1.21 x 10⁻⁴ year⁻¹.
t is the time = ??? years.
[A₀] is the initial percentage of carbon-14 = 100.0 %.
[A] is the remaining percentage of carbon-14 = 1/4[A₀] = 25.0 %.
∵ kt = ln [Ao]/[A]
∴ (1.21 x 10⁻⁴ year⁻¹)(t) = ln (100.0%)/[25.0 %]
(1.21 x 10⁻⁴ year⁻¹)(t) = 1.386.
∴ <em>t </em>= 1.386/
(1.21 x 10⁻⁴ year⁻¹) = <em>1.146 x 10⁴ year.</em>
Answer:
0.041 L = 41.3 mL
Explanation:
This problem we will solve by considering the stoichiometry of the reaction and the definition of molarity.
Number of moles in .800 L solution:
0.800 L x 0.0240 M = 0.800 L x .0240 mol/L = 0.0192 mol Fe³⁺
to form the precipitate Fe(OH)₃ we will need 3 times .0192
mol NaOH required = 0.057
given the concentration of 1.38 mol M NaOH we can calculate how many milliliters of NaOH will contain 0.057 mol:
1.L/1.38 mol NaOH x 0.057 mol NaOH = 0.041 L
0.041 L x 1000 mL/1L = 41.3 mL
A food web is a graphic representation of all possible energy pathways through an ecosystem.
Answer:
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Explanation:
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Mass of NaOH required = 12 g
<h3>Further explanation</h3>
Given
500 ml solution = 0.5 L
Molarity = 0.6 mol / L
Required
mass of NaOH
Solution
Molarity = moles of solute per liter of solution
M = n / V
solute = NaOH
moles of solute = n = M x V
n = 0.6 x 0.5
<em>n = 0.3 moles</em>
Mass of NaOH = mol x MW
mass = 0.3 x 40 = 12 g
