5.3 g of sodium carbonate and 6.0 g of acetic acid react to produce 2.2 g of carbon dioxide. Class 9

5.3 g of sodium carbonate and 6.0 g of acetic acid react to produce 2.2 g of carbon dioxide. Class 9

Question 1.

5.3 g of sodium carbonate and 6.0 g of acetic acid react to produce 2.2 g of carbon dioxide, 0.9 g of water, and 8.2 g of sodium acetate. Verify whether the law of conservation of mass is valid. Class 9

Answer:

Total mass of reactants = 5.3 g (sodium carbonate) + 6.0 g (acetic acid) = 11.3 g

Total mass of products = 2.2 g (carbon dioxide) + 0.9 g (water) + 8.2 g (sodium acetate) = 2.2 + 0.9 + 8.2 = 11.3 g

Mass of reactants = Mass of products = 11.3 g Since the total mass before and after the reaction is equal, the Law of Conservation of Mass is valid

Question 2.

If a species has 11 protons, 12 neutrons and 10 electrons then Class 9

(i) what is its atomic number and mass number?

(ii) is it neutral, a cation or an anion? Explain.

(iii) write its electronic configuration.

(iv) name the species.

Answer:

(i) Atomic number and mass number: Atomic number = number of protons = UMass number = number of protons + number of neutrons = 11 + 12 = 23

(ii) Is it neutral, a cation or an anion? It is a cation. A neutral atom has equal numbers of protons and electrons. This species has 11 protons but only 10 electrons. Since the number of protons (positive charges) is greater than the number of electrons (negative charges), the species carries a net positive charge of +1. A positively charged species is called a cation. It is represented as Na+.

(iii) Electronic configuration: The species has 10 electrons. Electronic configuration: 2, 8 (K-shell = 2, L-shell = 8)

(iv) Name of the species: Atomic number 11 corresponds to sodium. The species is a sodium cation, Na⁺ (sodium ion).