Answer:
1. From water vapor to the dry ice;
2. The potential energy is higher before the water vapor condenses;
3. The thermal energy is higher in the 2.0 kg block.
Explanation:
1. The heat flows from the system with high temperature to the system with low temperature. The water vapor is at 298 K, and the dry ice is at 194.5 K.
2. The energy of the molecules is related to the temperature and the physics state. At the gas state, the molecules are more agitated, and the energy is higher than the liquid state. So, when the vapor condenses to a liquid, the energy decreases.
3. The thermal energy can be calculated by:
Q = m*c*ΔT
Where m is the mass, c is the specific heat, and ΔT the variation in the temperature. So, when the mass increase, thermal energy also increases.
4) fission is a nuclear reaction where the nucleus of a reactant breaks apart
Answer: B) Crash 2; the force on the cart was stronger in this crash, so the force on the skateboard was also stronger.
Explanation:
Given reaction represents dissociation of bromine gas to form bromine atoms
Br2(g) ↔ 2Br(g)
The enthalpy of the above reaction is given as:
ΔH = ∑n(products)Δ
- ∑n(reactants)Δ
where n = number of moles
Δ
= enthalpy of formation
ΔH = [2*ΔH(Br(g)) - ΔH(Br2(g))] = 2*111.9 - 30.9 = 192.9 kJ/mol
Thus, enthalpy of dissociation is the bond energy of Br-Br = 192.9 kJ/mol
