Question

1. For one atom of lithium -6 I will need_____ atom of lithium -7 for an average atomic mass of 6.944? 2. For one atom of lithium -6 needed _____ Adams of lithium -7 for an average atomic mass of 6.944.

Answer 1

Answer:

For one atom of lithium -6 I will need_16.85____ atom of lithium -7 for an average atomic mass of 6.944 .

Explanation:

1 ) Let required atom be m .

$\frac{6\times 1 + 7\times m}{1 + m} = 6.944$

6 + 7m = 6.944 + 6.944m

7 m - 6.944 m = .944

.056 m = .944

m = 16.85

Answer 2

Here, we are required to find how many atoms of lithium -7 is to combine with 1 atom of lithium -6 for an average atomic mass of 6.944.

For one atom of lithium -6 I will need 16.86 atoms of lithium -7 for an average atomic mass of 6.944.

Let the total number of lithium -6 and lithium -7 required be; x.

Therefore, the number of lithium -7 required is;

(x-1)

Therefore;

{(1/x) × 6 + ((x-1)/x)× 7} = 6.944

Therefore, (6 + 7x - 7)/x = 6.944

And, 7x -1 = 6.944x

0.056x = 1

And, x = 1÷0.056 = 17.86 atoms.

Therefore, the number of lithium -7 atoms needed is;

x - 1 = 17.86 - 1 = 16.85 atoms of lithium -7.

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