Answer:
A and B
Explanation:
This is because there was emission of gamma (Y) radiations in both the reactions.
Answer:
31.5 mL of a 2.50M NaOH solution
Explanation:
Molarity (M) is an unit of concentration defined as moles of solute (In this case, NaOH), per liter of solvent. That is:
Molarity = moles solute / Liter solvent
If you want to make 525mL (0.525L) of a 0.150M of NaOH, you need:
0.525L × (0.150mol / L) = <em>0.07875 moles of NaOH</em>
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If you want to obtain these moles from a 2.50M NaOH solution:
0.07875mol NaOH × (1L / 2.50M) = 0.0315L = <em>31.5 mL of a 2.50M NaOH solution</em>
The mass of Calcium required to complete this reaction is 4.008 g.
- Law of conservation of mass states that In a closed system, mass cannot be produced or destroyed, but it can be changed from one form to another.
- The mass of the chemical constituents before a chemical reaction is equal to the mass of the constituents after the reaction.
- In several disciplines, including chemistry, mechanics, and fluid dynamics, the idea of mass conservation is widely applied.
In the given reaction mass of product after completion of reaction is 13.614 g that means total mass of constituents before reaction should also be 13.614.
So,
mass of Ca + mass of O₂ + mass of S = mass of CaSO4
Ca + 6.400 g + 3.206 g = 13.614 g
mass of Ca = 13.614 - 9.606 = 4.008 g
Therefore, by law of conservation of mass 4.008 g of Ca is required for the completion of the reaction.
Learn more about mass conservation here:
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Answer:
5.0 x 10⁹ years.
Explanation:
- It is known that the decay of a radioactive isotope isotope obeys first order kinetics.
- Half-life time is the time needed for the reactants to be in its half concentration.
- If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).
- Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
- The half-life of K-40 = 1.251 × 10⁹ years.
- For, first order reactions:
<em>k = ln(2)/(t1/2) = 0.693/(t1/2).</em>
Where, k is the rate constant of the reaction.
t1/2 is the half-life of the reaction.
∴ k =0.693/(t1/2) = 0.693/(1.251 × 10⁹ years) = 5.54 x 10⁻¹⁰ year⁻¹.
- Also, we have the integral law of first order reaction:
<em>kt = ln([A₀]/[A]),</em>
where, k is the rate constant of the reaction (k = 5.54 x 10⁻¹⁰ year⁻¹).
t is the time of the reaction (t = ??? year).
[A₀] is the initial concentration of (K-40) ([A₀] = 100%).
[A] is the remaining concentration of (K-40) ([A] = 6.25%).
∴ (5.54 x 10⁻¹⁰ year⁻¹)(t) = ln((100%)/( 6.25%))
∴ (5.54 x 10⁻¹⁰ year⁻¹)(t) = 2.77.
∴ t = 2.77/(5.54 x 10⁻¹⁰ year⁻¹) = 5.0 x 10⁹ years.
