How much thermal energy must be added to a 87.5 g sample of ice at -25oC completely melt the entire sample? As part of your work
1 answer:
Answer:
4.6 kJ
Explanation:
The energy required to raise the temperature of a substance from its initial temperature to a final temperature is given by:
Q = mcΔT
Where Q = energy, c = specific heat capacity of substance and ΔT = final temperature - initial temperature
Given that:
c = 2.1 kJ/kg°C, m = 87.5 = 0.0875 kg, ΔT = final temperature - initial temperature = 0 - (-25) = 25
Q = 0.0875 * 2.1 *25
Q = 4.6 kJ
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Answer:
Paper chromatography is a basic technique of chromatography. It consist in the separation of the mixe components using a solvent.
Explanation:
Paper chromatography is a basic technique of chromatography. It consists in the separation of the mixed components using a solvent.
Paper chromatography consists of put some dot of the mix using a glass capillary into a specialized paper, generally made of cellulose, this is called a stationary phase.
Then you put this paper into a camera of glass named, chromatography camera, where previously contain a solvent. The solvent also know as a mobile phase, the type can be defined before the test and involves a study of the kind of the mix, and the compound you want to separate.
The chromatography camera has to be closed all the time during the test, and you can't move at all because the movement of the solvent can alternate the result.
Very often, the solution of the solvent is a mix of different liquid substances with different polarities.
When the stationary phase put into the camera, the solvent starts to move up over the paper, until the separation of the compounds is observable.
the Rf is a value who relates the move of the mobile phase with the move of the distance traveled by the substance tested.
To undersant the paper chromatography, you can watch the images attached.
The first is an image of the chromatography camera.
The second one is an image of a cellulose paper after the chromatography is done. You can watch the dots who indicates the traveling of the compound across the paper.
The third one can show you the evolutions of paper chromatography, from the beginning to the end.
To calculate the Rf value you have to use the equation:
Rf = distance traveled by the substance/distance traveled by the solvent/
<u>Rf = 52mm/81mm =0.64</u>
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Answer is 0.289nm.
Explanation: The wt % of Fe and wt % of V is given for a Fe-V alloy.
wt % of Fe in Fe-V alloy = 85%
wt % of V in Fe-V alloy = 15%
We need to calculate edge length of the unit cell having bcc structure.
Using density formula,
For calculating edge length,
For calculating , we use the formula
Similarly for calculating , we use the formula
From the periodic table, masses of the two elements can be written
Specific density of both the elements are
Putting and
formula's in edge length formula, we get
By calculating, we get