We write DE = q+w, where DE is the internal energy change and q and w are heat and work, respectively.
(b)Under what conditions will the quantities q and w be negative numbers?
q is negative when heat flows from the system to the surroundings, and w is negative when the system does work on the surroundings.
As an aside: In applying the first law, do we need to measure the internal energy of a system? Explain.
The absolute internal energy of a system cannot be measured, at least in any practical sense. The internal energy encompasses the kinetic energy of all moving particles in the system, including subatomic particles, as well as the electrostatic potential energies between all these particles. We can measure the change in internal energy (DE) as the result of a chemical or physical change, but we cannot determine the absolute internal energy of either the initial or the final state. The first law allows us to calculate the change in internal energy during a transformation by calculating the heat and work exchanged between the system and its surroundings.
Explanation:
Brass (a copper-zinc alloy)-The brass bond is brittle because it is a metal alloy.
Rubber-Rubber bonding is covalent.
Barium sulfide (BaS) — Bonding is primarily ionic (but some covalent) depending on the respective Ba and S positions in the periodic table.
Solid xenon-Bonding is van der Waals in solid xenon, since xenon is a noble gas.
Bronze-Bonding is metallic in that it is an alloy with silver.
Nylon-The bonding in nylon is primarily covalent with some van der Waals Forces.
Aluminum phosphide (AlP)-Aluminum phosphide (AlP) bonding is covalent in principle but it also has some ionic character.
Hey there!:
Mass = 2.98 g
Volume = 2.12 L
Therefore:
Density = mass / volume
Density = 2.98 / 2.12
Density = 1.405 g/L
