Answer:
Cl⁻, Na⁺, OH⁻
Explanation:
The titration is:
CuCl₂(aq) + 2 NaOH(aq) → Cu(OH)₂(s) + 2 NaCl(aq)
In solution, before the reaction, the ions are Cu²⁺ and Cl⁻. The addition of NaOH (Na⁺ + OH⁻) produce the precipitation of Cu²⁺ forming Cu(OH)₂(s). When you reach the equivalence point, there is no Cu²⁺ because precipitates completely. All OH⁻ ions reacts when are added but when Cu²⁺ is finished, excess OH⁻ ions still in solution helping to detect the equivalence point.
Thus, ions present after the equivalence point are:<em> Cl⁻, Na⁺</em> (Don't react, spectator ions), and <em>OH⁻</em>.
Answer:
A. Peroxide breaking down into water and oxygen
Explanation:
Generally when it comes to changes, there are physical and chemical changes. In physical changes, there are no new substances been formed, however in chemical change new substances are formed.
A. Peroxide breaking down into water and oxygen
This is a chemical change.
B
. Bubbles forming when a pot of water is heated
This is a physical change
C. A pair of jeans soaked in water drying after hanging outside
This is a physical change
D
. A block of ice decreasing in size due to a change in temperature
This is a physical change.
Only option A is different from the rest,hence this is the answer.
Answer:
E. Water Freezing
Explanation:
Entropy refers to the degree of disorderliness of a system.
A. Water Evaporating: There is an increase in entropy, this is because the phase change is from liquid to gas. Gas particles are more disordered than liquid.
B. Dry Ice sublimating: Sublimating refers to a phase change from solid to gas. This is an increase in entropy, this is because the gas particles are more disordered than solid particles
C. Water Boiling: The phase change is from liquid to gaseous state. There is an increase in entropy. Gas particles are more disordered than liquid.
D. Ice melting: The phase change is from solid to liquid state. There is an increase in entropy. Liquid particles are more disordered than that of solid.
E. Water Freezing: The phase change is from liquid to solid state. There is a decrease in entropy. solid particles are less disordered than those of liquid.
