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Reptile [31]
2 years ago
10

scandium47 has a half-life of 35s. suppose you have a 45g sample of scadium 47 how much of the sample remains unchanged after 14

0 seconds
Chemistry
1 answer:
Mars2501 [29]2 years ago
4 0

 The much  of the sample that would remain  unchanged  after 140 seconds is 2.813 g

Explanation

Half life  is time taken for the quantity  to reduce  to half its original value.

if the half life  for Scandium  is 35 sec, then the number  of half life in 140 seconds

=140 sec/ 35 s = 4 half life

Therefore 45 g after first half life = 45 x1/2 =22.5 g

               22.5 g after second half life = 22.5 x 1/2 =11.25 g

            11.25 g after third half life = 11.25 x 1/2 = 5.625 g

             5.625 after  fourth half life = 5.625 x 1/2 = 2.813

therefore 2.813 g  of Scandium 47 remains  unchanged.

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Determine the LIMITING reactant in the following balanced equation:
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KBr is limiting reactant.

Explanation:

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Now we will compare the moles of reactant with product.

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                2              :              2

            0.03            :            0.03

             KBr            :              Br₂

                2             :               1

             0.03           :          1/2×0.03= 0.015

               Cl₂             :            KCl

                 1              :              2

            0.09            :           2/1×0.09 = 0.18

               Cl₂             :              Br₂

                1              :               1

             0.09           :            0.09

Less number of moles of product are formed by the KBr thus it will act as limiting reactant while Cl₂  is present in excess.

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