Half life is the time taken for a radioactive isotope to decay by half its original mass. In this case the half life of carbon-14 is 5.730 years.
Using the formula;
New mass = original mass × (1/2)^n; where n is the number of half lives (in this case n=1 )
New mass = 2 g × (1/2)^1
= 1 g
Therefore; the mass of carbon-14 that remains will be 1 g
Answer:
1.36 × 10³ mL of water.
Explanation:
We can utilize the dilution equation. Recall that:
Where <em>M</em> represents molarity and <em>V</em> represents volume.
Let the initial concentration and unknown volume be <em>M</em>₁ and <em>V</em>₁, respectively. Let the final concentration and required volume be <em>M</em>₂ and <em>V</em>₂, respectively. Solve for <em>V</em>₁:
Therefore, we can begin with 0.640 L of the 2.50 M solution and add enough distilled water to dilute the solution to 2.00 L. The required amount of water is thus:
Convert this value to mL:
Therefore, about 1.36 × 10³ mL of water need to be added to the 2.50 M solution.
Answer:
3.5 moles Fe
Explanation:
From the equation, Reaction of 2 moles of Fe₂O₃ with 1 mole of C produces 1 mole of Fe. When excess Fe₂O₃ is used, the only liming factor is C.
The ratio of amount of C used to the amount of Fe produced is 1:1
Therefore, if 3.5 moles of C are used, 3.5 moles of Fe are also produced.
Answer:
78 moles of the solute
Explanation:
From the question;
- Molarity of the solution is 6.50 M
- Volume of the solution is 12.0 L
We want to determine the number of moles needed
We need to know that;
Molarity = Number of moles ÷ Volume
Therefore;
Number of moles = Molarity × Volume
Hence;
Number of moles = 6.50 M × 12.0 L
= 78 moles
Thus, the moles of the solute needed is 78 moles
