First from the data given we are able to determine the empirical formula of the product. To do that we use the following algorithm:
1) Divide each percentage at the atomic mass of each element:
O 51.3 / 16 = 3.21
C 42.2 / 12 = 3.52
H 6.5 / 1 = 6.5
2) Now we divide the result to the lowest number, which is 3.21:
O 3.21 /3.21 = 1
C 3.52 /3.21 = 1.1 ≈ 1
H 6.5/3.21 = 2
So the empirical formula of the unknown compounds is:
CH₂O
We can conclude that the compound contains carbon, hydrogen and oxygen in the ratio given by the empirical formula:
C : H : O = 1 : 2 : 1
Answer:
Recall from the 1st law of thermodynamic - Energy Balance gives;
assuming : there is no change in kinetic and potential energy, a steady state process, etc.
ΔU = ΔQ + ΔW
For this system, ΔW = +ve (engine does the work)
ΔU = -2952J
ΔQ = -ve? (Heat energy is been released)
Since the heat energy is removed, the internal energy must increase by
-2952J = 642J - ΔQ
ΔQ = (642 + 2952) = 3594 J was released from the engine and the amount that must be cooled off
Now to find the change in the internal energy of the engine?
Note that as as soon as the heat is removed, there would not be any change in the internal energy of the system because all the energy from the burning of the measure of fuel has been removed.
so ΔU = 0J
Change one of the variables and try again
Answer: number of atoms is 5.21 · 10^24
Explanation: Atomic mass of Be is 9.012 g/mol.
Number of moles n = m/M = 78.0 g / 9.012 g/mol =
Multiply this with Avogadro number Na = 6.022*10^23 1/mol
