Naphthalene has C2-rotational axis passing through the C9-C10 bond. It has two C2-axes perpendicular to the principal C2-rotational axis (one is passing through the mid-point of the C9-C10 bond another passing through the midpoints of C2-C3, C9-C10, C6-C7 bonds).

Explanation:

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3 years ago

What is the composition, in atom percent, of an alloy that contains a) 44.5 lbm of silver, b) 84.7 lbm of gold, and c) 7.3 lbm o

Fed [463]

Answer: The atom percent of silver, gold and copper in the alloy is 43.08 %, 44.93 % and 11.99 % respectively

Explanation:

To convert the given masses into grams, we use the conversion factor:

1 lb = 453.6 grams

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

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

To calculate the atom percent of substance in sample, we use the equation:

$\%\text{ composition of substance}=\frac{\text{Moles of substance}\times N_A}{\text{Total moles of sample}\times N_A}\times 100$ ......(2)

where,

$N_A$ = Avogadro's number

Moles of Silver:

Mass of silver = 44.5 lb = 20185.2 grams

We know that:

Molar mass of silver = 107.87 g/mol

Putting values in equation 1, we get:

$\text{Moles of silver}=\frac{20185.2g}{107.87g/mol}=187.12mol$

Moles of Gold:

Mass of gold = 84.7 lb = 38419.9 grams

We know that:

Molar mass of gold = 196.97 g/mol

Putting values in equation 1, we get:

$\text{Moles of gold}=\frac{38419.9g}{196.97g/mol}=195.05mol$

Moles of Copper:

Mass of copper = 7.3 lb = 3311.3 grams

We know that:

Molar mass of copper = 63.55 g/mol

Putting values in equation 1, we get:

$\text{Moles of copper}=\frac{3311.3g}{63.55g/mol}=52.10mol$

Total moles of the sample =

For Silver:

Moles of silver = 187.12 moles

Total moles = [187.12 + 195.05 + 52.10] = 434.27 moles

Putting values in equation 2, we get:

$\%\text{ composition of silver}=\frac{187.12\times N_A}{434.27\times N_A}\times 100\\\\\%\text{ composition of silver}=43.08\%$

For Gold:

Moles of gold = 195.05 moles

Total moles = [187.12 + 195.05 + 52.10] = 434.27 moles

Putting values in equation 2, we get:

$\%\text{ composition of gold}=\frac{195.05\times N_A}{434.27\times N_A}\times 100\\\\\%\text{ composition of gold}=44.93\%$

For Copper:

Moles of copper = 52.10 moles

Total moles = [187.12 + 195.05 + 52.10] = 434.27 moles

Putting values in equation 2, we get:

$\%\text{ composition of copper}=\frac{52.10\times N_A}{434.27\times N_A}\times 100\\\\\%\text{ composition of copper}=11.99\%$

Hence, the atom percent of silver, gold and copper in the alloy is 43.08 %, 44.93 % and 11.99 % respectively

3 0

3 years ago