Answer is: the combined ionic bond strength of CrCl₂ and intermolecular forces between water molecules.
When chromium chloride (CrCl₂) is dissolved in water, the temperature of the water increases, heat of the solution is endothermic.
Dissociation of chromium chloride in water: CrCl₂(aq) → Cr²⁺(aq) + 2Cl⁻(aq).
Energy (the lattice energy) is required to pull apart the oppositely charged ions in chromium chloride.
The heat of hydration is liberated energy when the separated ions (in this example chromium cations and chlorine anions) attract polar water molecules.
Because the lattice energy is higher than the heat of the hydration (endothermic reaction), we can conclude that bonds between ions are strong (the electrostatic attraction between oppositely charged ions).
A good example is the mineral<span> plagioclase. Plagioclase is a member of the feldspar group, but </span>there<span> is more than one type of plagioclase.</span>
Answer:
The process in which a solid changes directly to a gas is called sublimation. It occurs when the particles of a solid absorb enough energy to completely overcome the force of attraction between them. Dry ice (solid carbon dioxide, CO2) is an example of a solid that undergoes sublimation.
The reaction between ammonium sulfate and calcium hydroxide is given below.
(NH₄)₂SO₄ + Ca(OH)₂ --> 2NH₃ + CaSO₄ + 2H₂O
From the balance equation, we can conclude that every 74 g of calcium sulfate reacted with enough amount of ammonium sulfate will yield 34 grams of ammonia. From the given amount,
(20 g calcium sulfate) x (34 grams ammonia / 74 g calcium sulfate)
= <em>9.19 g ammonia</em>
I believe the answer you are looking for is Static Friction. Static Friction is the force that holds an object in place until it starts to move. Then it switches to rolling friction.
For example, if you have a 1/2 ton truck sitting in front of you and the truck is in neutral. (meaning it can roll if pushed). The truck is extremely hard to move at first. That is because static friction is holding it in place until the amount of force exceeds the limit of static friction.
So if we continue to push at the truck and you feel it starting to move, then once it starts moving it is much easier to push, that is because we moved past static friction to rolling friction. Rolling friction is what helps slow things down. If you roll a ball across a carpet floor it eventually comes to a stop.
