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3 years ago

There's a 50 gram sample of our Ra-229 it is half-life is 4 minutes how much will be left after 12 minutes

1 answer:

7 0

The half life of an isotope is the amount of time it will take for the given isotope to decay till the point where it reaches half of what amount you had started with.

If the half life of Ra-229 is 4 minutes then every 4 minutes the sample is reduced to half of what you had before

4 minutes.) 50/2 Ra-229 --> 25g Ra-229

8 minutes.) 25/2 Ra-229 --> 12.5 Ra-229

12 minutes.) 12.5/2 Ra-229 --> 6.25 Ra-229 remaining

<em>I beleive this is the correct answer</em>

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3 years ago

A solution is made by adding 29.1 mL of concentrated perchloric acid ( 70.5 wt% , density 1.67 g/mL ) to some water in a volumet

Lera25 [3.4K]

Answer:

The concentration of the solution is 1.364 molar.

Explanation:

Volume of perchloric acid = 29.1 mL

Mass of the solution = m

Density of the solution = 1.67 g/mL

$m=1.67 g/mL\times 29.1 mL=48.597 g$

Percentage of perchloric acid in 48.597 solution :70.5 %

Mass of perchloric acid in 48.597 solution :

= $\frac{70.5}{100}\times 48.597 = 34.261 g$

Moles of perchloric acid = $\frac{34.261 g}{100.46 g/mol}=0.3410 mol$

In 29.1 mL of solution water is added and volume was changed to 250 mL.

So, volume of the final solution = 250 mL = 0.250 L (1 mL = 0.001 L)

$Molarity=\frac{Moles}{Volume (L)}$

$=\frac{0.3410 mol}{0.250 L}=1.364 M$

The concentration of the solution is 1.364 molar.

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3 years ago

Which action would shift this reaction away from solid calcium fluoride and toward the dissolved ions? which action would shift

ANTONII [103]

Hello!

The chemical reaction for the dissolving of calcium fluoride is the following:

CaF₂(s) ⇄ Ca⁺²(aq) + 2F⁻(aq)

In this reaction, and according to Le Chatelier's principle, the action that would shift this reaction away from solid calcium fluoride and towards the dissolved ions is the removing of fluoride ions.

Le Chatelier's principle states that in an equilibrium reaction, the system would shift in the opposite direction of the changes. If we remove fluoride ions from the system, it will shift towards the formation of more fluoride ions by dissolving more Calcium Fluoride to achieve equilibrium again.

Have a nice day!

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3 years ago

A metal melts at 450 degrees celsius. Is this property of the metal classified as chemical or physical?

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It's a physical property because it doesn't change the element of the metal.
does this make sense?

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