Question

In: Chemistry

12. A 15.7-g sample of sodium carbonate is added to a solution of acetic acid weighing...

12. A 15.7-g sample of sodium carbonate is added to a solution of acetic acid weighing 19.4 g. The two substances react, releasing carbon dioxide gas to the atmosphere. After reaction, the contents of the reaction vessel weighs 28.4 g.

What is the mass of carbon dioxide given off during the reaction?

13. Cadmium metal reacts vigorously with yellow crystals of sulfur to produce a yellow powder of cadmium sulfide. A chemist determines that 112 g of cadmium reacts with 32.1 g of sulfur. How much cadmium sulfide could be produced from 45.4 g of cadmium metal?

18. Pick if it is a chemical or physcial reaction

(a) Pure water is obtained from ocean water by evaporating the water, then condensing it.

	physical process
	chemical reaction

(b) Mercury is obtained by heating the substance mercury(II) oxide; oxygen is also obtained.

	physical process
	chemical reaction

(c) Zinc is produced through the electrolysis of aqueous zinc sulfate

	physical process
	chemical reaction

(d) Gold is obtained from river sand by panning (allowing the heavy metal to settle in flowing water).

Expert Solution

12.

Na2CO3 + 2CH3COOH = 2CH3COONa + CO2 + H2O

Initially total weight of reaction mixture = 15.7+19.4 = 35.1gm

After reaction weight = 28.4gm

Msss of CO2 given off = Loss in weight of mixture = 35.1-28.4= 6.7gm

13.

112 g of cadmium reacts with 32.1 g of sulfur to give 112+32.1=144.1gm of cadmium sulfide

1gm if cadmium will give 144.1/112gm of cadmium sulfide

45.4gm of cadmium will give 45.4*144.1/112 = 58.4gm of cadmium sulfide

18.

(a) Pure water is obtained from ocean water by evaporating the water, then condensing it.

physical process: No change of molecules

(b) Mercury is obtained by heating the substance mercury(II) oxide; oxygen is also obtained.

chemical reaction: Mercury oxide molecule breaks to give two new molecules.

(c) Zinc is produced through the electrolysis of aqueous zinc sulfate

chemical reaction: zinc sulfate gives pure zinc.

(d) Gold is obtained from river sand by panning (allowing the heavy metal to settle in flowing water).Comment

Physical process

:Gold is in pure form

queen_honey_blossom answered 1 year ago

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