Answer:
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It takes 31 s for 1.27 M H₃PO₄ to decrease its concentration to 7.0% of its initial value following first-order kinetics.
<h3>What is first-order kinetics?</h3>
First-order kinetics occur when a constant proportion of a reactant disappears per unit time.
Let's consider the following first-order kinetics reaction with a rate constant k = 0.086 s⁻¹.
2 H₃PO₄(aq) = P₂O₅(aq) + 3 H₂O(aq)
Given the initial concentation is [H₃PO₄]₀ = 1.27 M, the concentration representing 7.0% of this value is:
[H₃PO₄] = 7.0% × 1.27 M = 0.089 M
We can calculate the time elapsed (t) using the following expression.
ln ([H₃PO₄]/[H₃PO₄]₀) = - k × t
ln (0.089 M/1.27 M) = - 0.086 s⁻¹ × t
t = 31 s
It takes 31 s for 1.27 M H₃PO₄ to decrease its concentration to 7.0% of its initial value following first-order kinetics.
Learn more about first-order kinetics here: brainly.com/question/18916637
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The percent yield : 4. 84.58%
<h3>Further explanation</h3>
Reaction
CaCO₃ ⇄ CaO+CO₂
mass CaCO₃ = 2.3 × 10³ g
mol CaCO₃ (MW=100.0869 g/mol) :
From the equation, mol CaCO₃ : CaO = 1 : 1, so mol CaO=22.98
mass CaO(MW=56.0774 g/mol)⇒ (theoretical) :
The percent yield :
Democritus believed that the universe was composed of atoms, correctly, of course. However, at the time, Plato's and Aristotle's hypothesi were just as valid because everyone was a philosopher. There were no scientists back then.
