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3 years ago

Nitrogen has a half life of 10 days. If you have a 75 gram sample how much is remaining after 20 days ?

Chemistry

1 answer:

CaHeK987 [17]3 years ago

3 0

There is 9.375 g of nitrogen. This is because when a half-life passes, the mass becomes 2 times less. Since two half-lives have passed, you need to divide by 4.

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The balanced equation for the reaction of aqueous Pb(ClO3)2 with aqueous NaI is Pb(ClO3)2(aq)+2NaI(aq)⟶PbI2(s)+2NaClO3(aq) What

ryzh [129]

Answer : The mass of $PbI_2$ precipitate produced will be, 9.681 grams.

Explanation : Given,

Molarity of NaI = 0.210 M

Volume of solution = 0.2 L

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First we have to calculate the moles of $NaI$ .

$\text{Moles of }NaI=\text{Molarity of }NaI\times \text{Volume of solution}=0.210M\times 0.2L=0.042moles$

Now we have to calculate the moles of $PbI_2$ .

The balanced chemical reaction is,

$Pb(ClO_3)_2(aq)+2NaI(aq)\rightarrow PbI_2(s)+2NaClO_3(aq)$

From the balanced reaction we conclude that

As, 2 moles of $NaI$ react to give 1 mole of $PbI_2$

So, 0.042 moles of $NaI$ react to give $\frac{0.042}{2}=0.021$ moles of $PbI_2$

Now we have to calculate the mass of $PbI_2$ .

$\text{Mass of }PbI_2=\text{Moles of }PbI_2\times \text{Molar mass of }PbI_2$

$\text{Mass of }PbI_2=(0.021mole)\times (461.01g/mole)=9.681g$

Therefore, the mass of $PbI_2$ precipitate produced will be, 9.681 grams.

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Nitrogen has a half life of 10 days. If you have a 75 gram sample how much is remaining after 20 days ?​

Nitrogen has a half life of 10 days. If you have a 75 gram sample how much is remaining after 20 days ?