To solve this problem, we should recall the law of
conservation of energy. That is, the heat lost by the aluminium must be equal
to the heat gained by the cold water. This is expressed in change in enthalpies
therefore:
- ΔH aluminium = ΔH water
where ΔH = m Cp (T2 – T1)
The negative sign simply means heat is lost. Therefore we
calculate for the mass of water (m):
- 0.5 (900) (20 – 200) = m (4186) (20 – 0)
m = 0.9675 kg
Using same mass of water and initial temperature, the final
temperature T of a 1.0 kg aluminium block is:
- 1 (900) (T – 200) = 0.9675 (4186) (T – 0)
- 900 T + 180,000 = 4050 T
4950 T = 180,000
T = 36.36°C
The final temperature of the water and block is 36.36°C
Answer:
30N in the direction the 45N acts.
Explanation:
Fnet = F1 + F2 (the vector sum of the forces)
Assigning a positive direction to the 45N force and a negative direction to the 15N force gives:
Fnet = 45 - 15
Fnet = 30N
Since the answer is positive, it is in the direction the 45N force acts.
Answer:
"The lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by thePauli principle in a particular set of degenerate orbitals" is known as Hund's rule.
Explanation:
Pauli's Exclusion principle states that "two or more electrons can not have the same values of the set of all quantum numbers in an atom or a molecule".
So, the given statement <em>is not</em> Pauli's Exclusion principle.
Hund's rule states that the lowest energy configuration of an atom is that one in which the maximum number of parallel spins of the electrons are present.
The given statement is "The lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli principle in a particular set of degenerate orbitals", which is same as the Hund's rule.
Thus, the given statement is Hund' rule.
Heisenberg's uncertainty principle states that the momentum and position of an object can not be measured exactly at the same time.
So, the given statement <em>is not</em> Heisenberg's uncertainty principle.
Aufbau principle tells about the filling of the electrons in subshells of an atom. Therefore, the given statement <em>is not </em>Aufbau principle.
