Chemistry
Distinguish between the following pairs of substances :
(i) Sodium sulphide and sodium sulphite
(ii) HCl gas and chlorine gas
Practical Chemistry
9 Likes
Answer
(i) On addition of dil. sulphuric acid to sodium sulphide, hydrogen sulphide (H2S) gas is evolved which can be identified by its rotten egg smell. Hydrogen sulphide gas turns moist lead acetate paper silvery black.
Na2S + H2SO4 ⟶ Na2SO4 + H2S ↑
On addition of dil. sulphuric acid to sodium sulphite, sulphur dioxide (SO2) gas is evolved. Sulphur dioxide gas has a suffocating odour and turns lime water milky and potassium permanganate solution from pink to clear colourless.
Na2SO3 + H2SO4 (dil.) ⟶ Na2SO4 + H2O + SO2↑
(ii) HCl and chlorine gas
Chlorine (Cl2) turns moist starch iodide paper blue black whereas HCl does not.
Cl2 + 2KI ⟶ 2KCl + I2
Starch + I2 ⟶ Blue black colour
Answered By
3 Likes
Related Questions
Name the first three halogens. Give their physical state and colour.
A heavy crystalline white solid on heating in a test tube crumbles with a crackling sound and gives a reddish brown residue which changes to yellow and partly fuses with the glass and stains it yellow. A brown gas is also evolved. A glowing wooden splinter relights when held near the products evolved.
(i) Name the brown gas evolved.
(ii) What is the residue left in the test tube?
(iii) Write the formula of the crystalline white solid.
Al2O3 is the formula of Aluminium oxide. Write the formulae of :
(i) Aluminium nitrate
(ii) Aluminium phosphate
The electronic configuration of three elements A, B and C are as follows :
A — 2, 8, 8, 2;
B — 2, 8, 7
C — 2, 4
(i) Which of these can form cations ?
(ii) Which of these can form anions ?
(iii) Write a formula of a covalent compound formed using these elements