Question

(1) Define formula unit. Calculate the formula unit
mass of Na2CO3. (Given atomic mass :
Na = 23 u, C = 12 u, O = 16 u)
(ii) Give any three differences between atom and
molecule.

plz help me out...all my friend ​

Answer 1

Answer:

this is your Answer

Explanation:

1.  In a reaction 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium ethanoate. Show that these observations are in agreement with the law of conservation of mass carbonate.

Ans.

Sodium carbonate+Ethanoic acid→Sodium ethanoate+Carbon dioxide+Water5.3 g+6 g→8.2 g+2.2 g+0.9 g

        LHS                        RHS

        11.3 g        =        11.3 g

        (Mass of reactant) (Mass of product)

        This shows, that during a chemical reaction mass of reactact = mass of product.

2.  Hydrogen and oxygen combine in the ratio of 1 : 8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?

Ans. Ratio of H : O by mass in water is:

        Hydrogen : Oxygen → H2O

        1 : 8 = 3 : x

        x = 8 × 3

        ∴ 24 g of oxygen gas would be required to react completely with 3 g of hydrogen gas.

Answer 2

1. The dalton or unified atomic mass unit it denotes by symbols (Da or u) is a unit of mass mostly used in chemistry. It is defined as 1/12 of the mass of an unbound neutral atom of carbon-12 .

1 Dalton = 1 .66 × 10-²⁷ kg.

2. atom is the smallest particle in the element were as molecule is form when two or more atom of an element come together and form bonds