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Stella [2.4K]
3 years ago
7

The half life of Po-218 is three minutes. How much of a 200 atom sample will remain after 15 minutes

Chemistry
1 answer:
MakcuM [25]3 years ago
6 0
<h3>Answer:</h3>

6.25 atoms

<h3>Explanation:</h3>

<u>We are given</u>;

  • The half life of Po-218 is 3 minutes
  • Initial sample is 200 atom
  • Time of decay is 15 minutes

We are required to calculate the remaining mass after decay;

Half life refers to the time taken for original amount of a radioactive sample to decay to a half.

To calculate the remaining mass we use the formula;

N = N₀ × 0.5^n where n is the number of half lives, N is the new amount and N₀ is the original amount.

n = 15 min ÷ 3 min

  = 5

Therefore;

New amount = 200 atom × 0.5^5

                      = 6.25 atoms

Therefore; the amount of the sample that will remain after 15 minutes is 6.25 atoms.

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<u>Answer:</u> The number of moles of weak acid is 4.24\times 10^{-3} moles.

<u>Explanation:</u>

To calculate the moles of KOH, we use the equation:

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We are given:

Volume of solution = 43.81 mL = 0.04381 L      (Conversion factor: 1L = 1000 mL)

Molarity of the solution = 0.0969 moles/ L

Putting values in above equation, we get:

0.0969mol/L=\frac{\text{Moles of KOH}}{0.04381}\\\\\text{Moles of KOH}=4.24\times 10^{-3}mol

The chemical reaction of weak monoprotic acid and KOH follows the equation:

HA+KOH\rightarrow KA+H_2O

By Stoichiometry of the reaction:

1 mole of KOH reacts with 1 mole of weak monoprotic acid.

So, 4.24\times 10^{-3}mol of KOH will react with = \frac{1}{1}\times 4.24\times 10^{-3}=4.24\times 10^{-3}mol of weak monoprotic acid.

Hence, the number of moles of weak acid is 4.24\times 10^{-3} moles.

6 0
3 years ago
I don’t know the answers to these pls help
stepladder [879]

Answer:

4. Option C. Pentane.

5. Option D.

Explanation:

4. Hydrocarbons are compound containing carbon and hydrogen only. Hydrocarbons are said to be saturated when they contain only carbon to carbon single bond. All alkanes are saturated hydrocarbon.

The correct answer is pentane.

5. Isomerism is the phenomenon whereby two or more compounds have the same molecular formula but different structural patterns. The compounds involved are called isomers.

A careful observation of the diagram above shows that only option D satisfied the definition of Isomerism as the two compound both have the same molecular formula as C3H8O but different structural patterns.

Note: option C does not contain isomers as Isomerism can not occur in a compound having just 1 carbon atom.

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Burka [1]

Answer:

The periodic table of elements arranges all of the known chemical elements in an informative array. Elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass. ... For instance, all the group 18 elements are inert gases.

Explanation:

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3 years ago
Citric acid (right) is concentrated in citrus fruits and plays a central metabolic role in nearly every animal and plant cell.
arlik [135]

<u>0.549 mol</u> of citric acid are in 1.50 qt of lemon juice (d = 1.09 g/mL) that is 6.82% citric acid.

<h3>What is citric acid?</h3>

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Every year, more than two million tonnes of citric acid are produced. It is frequently employed as a chelating agent, an acidifier, and a flavouring

Citrates, which include salts, esters, and the polyatomic anion present in solution, are derivatives of citric acid. Trisodium citrate is an example of the former; triethyl citrate is an example of an ester.

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8 0
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Which of the following shows 3x + 15 + 6x – 7 + y in simplest terms?
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Answer:

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We know this because you add 3x and 6x to get 9x

then we only have one y so put y by itself then subtract 15 and y which gets us 8

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