Answer:
0.643 mol.
Explanation:
where, P is the pressure of the gas in atm (P = 4.0 atm).
V is the volume of the gas in L (V = 4000 mL = 4.0 L).
n is the no. of moles of the gas in mol (n = ??? mol).
R is the general gas constant (R = 0.0821 L.atm/mol.K),
T is the temperature of the gas in K (T = 30ºC + 273 = 303 K).
∴ n = PV/RT = (4.0 atm)(4.0 L)/(0.0821 L.atm/mol.K)(303 K) = 0.643 mol.
The standard units of measurement are particularly important to scientists because they make the result more accurate and precise.
When the average value of the different measurements is similar to the correct value then the measurement is said to be accurate and the phenomenon is said to be accurate.
When the values of measurement are close to each other then the result is said to be precise and the phenomena are said to be precise and need to do for the better accuracy of results.
Therefore, they make the result more accurate and precise.The standard units of measurement are particularly important to scientists.
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Answer:
Explanation: The standred units of measurments are important to scientists because they are the same measurments that all scientist take to make sure that they all have the correct results.
b. A 100.0 g sample of liquid ethanol vaporizes at its boiling point. Hvap = 38.6 kJ/mol
The heat required for the following two processes are:
a. 10.74 KJ
b. 83.92 KJ
Part a)
Given:
Mass (m) of ethanol = 100g
Heat of fusion, Hfus = 4.94 kJ/mol
To find:
Heat (Q) =?
Mass of C₂H₅OH = 100g
Molar mass of C₂H₅OH = (2x12)+ (5x1) + 16 + 1 = 46g/mol
Number of Mole = Mass /Molar Mass
Number of mole (n) of C₂H₅OH = 100/46 = 2.174 moles.
Calculation for Heat of fusion:
Q = n x Hfus
Q = 2.174 mol x 4.94 kJ/mol
Q = 10.74KJ
Therefore, 10.74 KJ of heat is required to melt the ethanol.
Part b)
Given:
Mass of C₂H₅OH = 100g
Heat of vaporization, Hvap = 38.6 kJ/mol
To find:
Heat (Q) =?
Calculation for Heat of vaporization:
As calculated above, the number of mole in 100g of ethanol, C₂H₅OH is 2.174 moles.
The heat required to vaporize the ethanol can be obtained as follow:
Q = n x Hvap
Q = 2.174 mol x 38.6 kJ/mol
Q = 83.92 KJ
Therefore, 83.92 KJ of heat is required to vaporize the ethanol.
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Answer:
A. 10.74 KJ
B. 83.92 KJ
Explanation:
A. Data obtained from the question include the following:
Mass (m) of ethanol = 100g
Heat of fusion, Hfus = 4.94 kJ/mol
Heat (Q) =..?
Next, we shall determine the number of mole in 100g of ethanol, C2H5OH. This is illustrated below:
Mass of C2H5OH = 100g
Molar mass of C2H5OH = (2x12)+ (5x1) + 16 + 1 = 46g/mol
Number of mole (n) of C2H5OH =..?
Mole = Mass /Molar Mass
Number of mole (n) of C2H5OH = 100/46 = 2.174 moles.
Now, we can obtain the heat required to melt the ethanol as follow:
Q = n x Hfus
Q = 2.174 mol x 4.94 kJ/mol
Q = 10.74KJ
Therefore, 10.74 KJ of heat is required to melt the ethanol.
B. Data obtained from the question include the following:
Mass of C2H5OH = 100g
Heat of vaporisation, Hvap = 38.6 kJ/mol
Heat (Q) =..?
As calculated above, the number of mole in 100g of ethanol, C2H5OH is 2.174 moles.
The heat required to vaporise the ethanol can be obtained as follow:
Q = n x Hvap
Q = 2.174 mol x 38.6 kJ/mol
Q = 83.92 KJ
Therefore, 83.92 KJ of heat is required to vaporise the ethanol.
C. From the above calculations, a higher amount of heat energy i.e 83.92 KJ is required to vaporise the ethanol and a lesser amount of heat energy i.e 10.74 KJ is needed to melt the ethanol.
The difference between light reflection and refraction is simple. In reflection, the light ray striking the plane returns to the originating source or medium as the waves spring off the surface. in refraction, the waves go through the surface and it alters their speed and direction.
Reflection is the bouncing back of light when it strikes a smooth surface. Generally occurs on shinny surfaces that only allow rebounding of light without permitting penetration through it. In this process, light bounces back and returns back in the same direction.
Refraction is the bending of light rays when it travels from one medium to another. This occurs in transparent surfaces that allow bending of the ray to a different medium.
In this process, light changes path i.e travels from one medium to another.
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Using, the table given above, one can conclude that, IT IS NOT ALWAYS POSSIBLE TO IDENTIFY A SUBSTANCE AS A COMPOUND, MIXTURE, PURE SUBSTANCE OR AN ELEMENT JUST BY LOOKING AT THEM.
Looking at the table, you will observe that, some of the substances listed under mixtures are actually compounds. That is, combination of hydrogen and oxygen will form water, which is a compound. Also, combination of sodium and chlorine will form sodium chloride, which is a compound.
2) The metal skewer gets so hot that you drop your marshmallows in the campfire because of ___________.
3) You lay on that same rock at night so that you can keep warm by _________.
4) The cause of whether systems on Earth is __________.
5) You are in the top bunk of a bunk bed and you want to turn the air conditioner on while your friend on the bottom bunk is fine is caused by __________.
PLEASE HELP I NEED THIS TONIGHT!!!