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2 years ago

If you have 200 grams of a radioactive sample, how many grams would be left after three half-lives?

1 answer:

3 0

Well, after 1 half life, depending on whatever the amount is, 50% of the original content and or remaining content will undergo decay, as it is unstable.

Original content - 200g

1 half life - 100 g
2 half life - 50 g
3 half life - 25 g

The correct solution would be D. 25 g.

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Formula mass, molar mass and Avagadro's number.

Explanation:

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3 years ago

If a substance has ph of 3.2 what is the poh

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3 years ago

g When aqueous solutions of and are mixed, a solid forms. Determine the mass of solid formed when 140.7 mL of 0.1000 M is mixed

solong [7]

The question is incomplete, the complete question is:

When aqueous solutions of NaCl and $Pb(NO_3)_2$ are mixed, a solid forms. Determine the mass of solid formed when 140.7 mL of 0.1000 M NaCl is mixed with an excess of an aqueous solution of

<u>Answer:</u> The mass of lead chloride produced is 1.96 g

<u>Explanation:</u>

Molarity is defined as the amount of solute expressed in the number of moles present per liter of solution. The units of molarity are mol/L. The formula used to calculate molarity:

$\text{Molarity of solution}=\frac{\text{Moles of solute}\times 1000}{ \text{Volume of solution (mL)}}$ .....(1)

Given values:

Molarity of NaCl = 0.1000 M

Volume of the solution = 140.7 mL

Putting values in equation 1, we get:

$0.1000=\frac{\text{Moles of NaCl}\times 1000}{140.7}\\\\\text{Moles of NaCl}=\frac{0.1000\times 140.7}{1000}=0.01407mol$

The chemical equation for the reaction of NaCl and lead nitrate follows:

$Pb(NO_3)_2(aq)+2NaCl(aq)\rightarrow PbCl_2(s)+2NaNO_3(aq)$

By the stoichiometry of the reaction:

If 2 moles of NaCl produces 1 mole of lead chloride

So, 0.01407 moles of NaCl will produce = $\frac{1}{2}\times 0.01407=0.007035mol$ of lead chloride

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

The equation used is:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(2)

Molar mass of lead chloride = 278.1 g/mol

Plugging values in equation 2:

$\text{Mass of lead chloride}=(0.007035mol\times 278.1g/mol)=1.96g$

Hence, the mass of lead chloride produced is 1.96 g

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3 years ago

How is a nonrenewable source different from a renewable one

Lady bird [3.3K]

A Nonrewnewable source is hard to get back from its source, while a renewable source is easy to get back from its source.

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