Answer:
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Answer: 72.41% and 26.90% respectively.
Explanation:
At 60°C, you can dissolve 46.4g of acetanilide in 100mL of ethanol. If you lower the temperature, at 0°C, you can dissolve just 12.8g, which means (46.4g-12.8g)=33.6g of acetanilide must have precipitated from the solution.
We can calculate recovery as:
![\%R=\frac{crystalized\ mass}{initial\ mass}*100 =\frac{33.6\ g}{46.4\ g}*100=72.41\%](https://tex.z-dn.net/?f=%5C%25R%3D%5Cfrac%7Bcrystalized%5C%20mass%7D%7Binitial%5C%20mass%7D%2A100%20%3D%5Cfrac%7B33.6%5C%20g%7D%7B46.4%5C%20g%7D%2A100%3D72.41%5C%25)
So the answer to the first question is 72.41%.
For the second part just use the same formula, the mass of the precipitate is the final mass minus the initial mass, (171mg-125mg)=46mg.
![\%R=\frac{crystalized\ mass}{initial\ mass}*100 =\frac{46\ mg}{171\ mg}*100=26.90\%](https://tex.z-dn.net/?f=%5C%25R%3D%5Cfrac%7Bcrystalized%5C%20mass%7D%7Binitial%5C%20mass%7D%2A100%20%3D%5Cfrac%7B46%5C%20mg%7D%7B171%5C%20mg%7D%2A100%3D26.90%5C%25)
So the answer to the second question is 26.90%.
The answer is (2) Copper. Because copper is consist of atom. If it is decomposed, the atom will be changed. While chemical change is just the break down and form of chemical bonds between atoms.
Answer: If a hydrogen atom and a helium atom have the same kinetic energy then the wavelength of the hydrogen atom will be roughly equal to the wavelength of the helium atom.
Explanation:
The relation between energy and wavelength is as follows.
![E = \frac{hc}{\lambda}\\](https://tex.z-dn.net/?f=E%20%3D%20%5Cfrac%7Bhc%7D%7B%5Clambda%7D%5C%5C)
This means that energy is inversely proportional to wavelength.
As it is given that energy of a hydrogen atom and a helium atom is same.
Let us assume that
. Hence, relation between their wavelengths will be calculated as follows.
... (1)
... (2)
Equating the equations (1) and (2) as follows.
![E_{hydrogen} = E_{helium} = E'\\\frac{hc}{\lambda_{hydrogen}} = \frac{hc}{\lambda_{helium}} = E'\\\lambda_{helium} = \lambda_{hydrogen} = E'](https://tex.z-dn.net/?f=E_%7Bhydrogen%7D%20%3D%20E_%7Bhelium%7D%20%3D%20E%27%5C%5C%5Cfrac%7Bhc%7D%7B%5Clambda_%7Bhydrogen%7D%7D%20%3D%20%5Cfrac%7Bhc%7D%7B%5Clambda_%7Bhelium%7D%7D%20%3D%20E%27%5C%5C%5Clambda_%7Bhelium%7D%20%3D%20%5Clambda_%7Bhydrogen%7D%20%3D%20E%27)
Thus, we can conclude that if a hydrogen atom and a helium atom have the same kinetic energy then the wavelength of the hydrogen atom will be roughly equal to the wavelength of the helium atom.