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3 years ago

Element X had a mass of 300g and a 1/2 life of 10 years. how many grams will remain after 40 years?

Chemistry

1 answer:

kiruha [24]3 years ago

3 0

<h3>Answer:</h3>

18.75 grams

<h3>Explanation:</h3>

Half-life refers to the time taken by a radioactive material to decay by half of the original mass.
In this case, the half-life of element X is 10 years, which means it takes 10 years for a given mass of the element to decay by half of its original mass.
To calculate the amount that remained after decay we use;

Remaining mass = Original mass × (1/2)^n, where n is the number of half-lives

Number of half-lives = Time for the decay ÷ Half-life

= 40 years ÷ 10 years

= 4

Therefore;

Remaining mass = 300 g × (1/2)⁴

= 300 g × 1/16

= 18.75 g

Hence, a mass of 300 g of an element X decays to 18.75 g after 40 years.

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Answer:

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Explanation:

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In this case, since the acid is monoprotic and the KOH has one hydroxyl ion only, we can see that at the equivalence point the moles of both of them are the same:

$n_{acid}=n_{KOH}$

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$n_{acid}=1.70g*\frac{1mol}{84.48g}=0.0201mol$

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