Answer:
Add Iodine-KI reagent to a solution or directly on a potato or other materials such as bread, crackers, or flour. A blue-black color results if starch is present. If starch amylose is not present, then the color will stay orange or yellow
The answer would be MgO, as you spilt the two.
Correct answer is option E. <span>It is a redox reaction in which Zn is oxidized at the anode, and V is reduced at the cathode.
Reason:
In above reaction, the oxidation state of VO3- is +5, while that of VO2 is +4. Thus there is reduction of V from +5 to +4
In case of Zn, oxidation state of Zn is increased from 0 to +2, Thus process is referred as oxidation. </span>
Answer:
<em>When salt is dissolved in water</em>, many physical properties change, among them the so called colligative properties:
- The vapor pressure of water decreases,
- The boiling point increases,
- The freezing point decreases, and
- Osmotic pressure appears.
Explanation:
Colligative properties are the physical properties of the solvents whose change is determined by the number of particles (moles or ions) of the solute added.
The colligative properties are: vapor pressure, boiling point, freezing point, and osmotic pressure.
<u>Vapor pressure</u>:
The vapor pressure is the pressure exerted by the vapor of a lquid over its surface, in a closed vessel.
The vapor pressure increases when a solute is added, because the presence of the solute causes less solvent molecules to be near the surface ready to escape to the vapor phase, which means that the vapor pressure is lower.
<u>Boiling point</u>:
The boiling point is the temperature at which the vapor pressure of the liquid equals the atmospheric pressure. Since we have seen that the vapor pressure of water decreases when a solute occupies part of the surface, now more temperature will be required for the water molecules reach the atmospheric pressure. So, the boiling point increases when salt is dissolved in water.
<u>Freezing point</u>:
The freezing point is the temperarute at which the vapor pressure of the liquid and the solid are equal. Since, the vapor pressure of water with salt is lower than that of the pure water, the vapor pressure of the liquid and solid with salt will be equal at a lower temperature. Hence, the freezing point is lower (decreases).
<u>Osmotic pressure</u>:
Osmotic pressure is the additional pressure that must be exerted over a solution to make that the vapor pressure of the solvent in the solution equals the vapor pressure of the pure solvent. This additional pressure is proportional to the concentration of the solute: the higher the salt concentration the higher the osmotic pressure.
Answer:
Copper ions are reduced into copper atoms.
Cu²⁺₍aq₎ + 2e⁻ → Cu₍s₎
Explanation:
During electrolysis, the positive H⁺ and Cu⁺ ions move to the negative cathode and negative OH⁻ and Cl⁻ ions move to the positive anode.
At cathode, copper ions are preferentially discharged due to the low electromotive force required to discharge them compared to the hydrogen ion. The copper ions gain the two electrons lost by the chloride ions when the are discharged. (2 Cl⁻₍aq₎ → Cl₂₍g₎ + 2e⁻)
Thus the half equation is as follows:
Cu²⁺₍aq₎ + 2e⁻ → Cu₍s₎
