Answer: B -Network solids
Ionic solids are held by positive and negative charged ions bonded by electrostatic forces. The electrostatic force is much stronger than dipole–dipole interactions, London dispersion forces, hydrogen bonding.
Molecular solids are held by dipole–dipole interactions, London dispersion forces, or hydrogen bonds. Benzene is an example of this. These inter-molecular force are much weaker than electrostatic force.
The metallic bonds are much weaker than electrostatic force. Similarly, in non-metallic solids the atoms are held by covalent bonds. These covalent bonds are weaker than the electrostatic force.
Thus we can conclude that electrostatic force is the strongest when compared to dipole–dipole interactions, London dispersion forces, hydrogen bonding,covalent and metallic bonds. Thus ionic solids will have the highest melting point as more energy is required to break the ionic bonds as this is the strongest bond compared to the other bonds.
Answer:
A i. Internal energy ΔU = -4.3 J ii. Internal energy ΔU = -6.0 J B. The second system is lower in energy.
Explanation:
A. We know that the internal energy,ΔU = q + w where q = quantity of heat and w = work done on system.
1. In the above q = -7.9 J (the negative indicating heat loss by the system). w = 3.6 J (It is positive because work is done on the system). So, the internal energy for this system is ΔU₁ = q + w = -7.9J + 3.6J = -4.3 J
ii. From the question q = +1.5 J (the positive indicating heat into the system). w = -7.5 J (It is negative because work is done by the system). So, the internal energy for this system is ΔU₂ = q + w = +1.5J + (-7.5J) = +1.5J - 7.5J = - 6.0J
B. We know that ΔU = U₂ - U₁ where U₁ and U₂ are the initial and final internal energies of the system. Since for the systems above, the initial internal energies U₁ are the same, then we say U₁ = U. Let U₁ and U₂ now represent the final energies of both systems in A i and A ii above. So, we write ΔU₁ = U₁ - U and ΔU₂ = U₂ - U where ΔU₁ and ΔU₂ are the internal energy changes in A i and A ii respectively. Now from ΔU₁ = U₁ - U, U₁ = ΔU₁ + U and U₂ = ΔU₂ + U. Subtracting both equations U₁ - U₂ = ΔU₁ - ΔU₂
= -4.3J -(-6.0 J)= 1.7 J. Since U₁ - U₂ > 0 , U₂ < U₁ , so the second system's internal energy increase less and is lower in energy and is more stable.
Answer:
Buffer is the chemical substance that addition of acids and bases, maintaining constant environment,its called Buffer.
Explanation:
- Buffers are use in the system to maintain the value of pH, and the contain the pH value is not to change.
- Buffer maintain the body of pH for the optimal activity,and they are solution of pH constant.
- Buffer in used in the lab and that to maintain growth of the micro tissues and the culture media.
- Buffer are used in maintain necessary optimal reaction activity,determine the indicator of solution with pH.
- Buffer capacity is that concentration to the buffering agent, is the very small increase,buffer capacity to the pH is 32% , of the maximum value of pH.
- Buffers in a acid regions to the desired of that value to the particular buffer agent.
- Buffers can be made from that a mixture of the base and acid, buffer can be a wide range of the obtained.
- Buffers that the pH calculation and they required to performed in the critic acid that the overlap over the buffer range.
NaCl would form because it’s a single replacement reaction
