Question

tration : Use a small beaker. I00-mL or 150-ml beaker and fill about ½ full of water. Cut a small piece of potassium metal, about the size of a small pea, place on a paper towel and quickly wipe off the mineral oil. Drop the small piece of metal into the Phenolphthalein may be added to indicate the formation of a basic solution. The may be lit. gas Hazard: Do not allow the potassium metal to be exposed to air for longer than about 30 seconds. The metal will react with the oxygen and moisture in the air What did you see that indicated a reaction occurred or did not occur? oecured or Write a balanced chemical equation icdig he physical state on cach species Write atomic element, covalent element, covalent compound or ionic compound under b. each species Write a word equation: potassium metal reacts in water to form potassium hydroxide and hydrogen gas Instructor initial 3) Instructor Demonstration: Use a test tube and fill about 1/3 full of water. Scrape away as much of the white coating as possible to obtain a shiny metal surface. Drop the small piece of metal into the water. Phenolphthalein may be added to indicate the formation of a basic solution. The hydrogen gas may be lit Ca(s) +H,0) Ca(OH)2(aq) H2(g) What did you see that indicated a reaction occurred or did not occur? a. Write a balanced chemical equation including the physical state on each species. b. Write atomic element, covalent element, covalen t compound or ionic compound under each species Write a word equation: Instructor initial

Answer 1

Ans:- 2. (A) potassium metal react with water rapidly and forms colourless solution of KOH (potassium hydroxide) and in presence of phenolphthalein it gives pink coloure solution due to its basic ph and form H₂ also. equation as follow

2K⁺_(s) + 2H⁺₂O ^-_(l)$\rightarrow$ 2K⁺OH^-_(aq)+ H⁺₂(g)

(B).- K⁺ , H⁺ , O^- ,OH^- .

Ans:-3. (a)- calcium react with water actively and forms CaOH (calcium hydroxide) and gives pink coloure in presence of phenolpthalein and forms Hydrogen gas also the balance equation is following.

Ca²⁺_(s) + 2H⁺₂O^-_(l)$\rightarrow$ Ca²⁺(OH)^-_2(aq) + H⁺_(g)

(B).- Ca²⁺ , H⁺ ,O^- ,OH^- .