question_answer

  (a) For making cake, baking powder istaken. If at home your mother uses baking soda instead of baking powder in cake. (i) How will it affect the taste of the cake and why? (ii) How can baking soda be converted into baking powder? (iii) What is the role of tartaric acid added to baking soda? (b) Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting. Or (a) A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water.  Identify X, Y, G and Z. (b) What happens when nitric acid is added to egg shell?

Answer:

  (a) (i) Baking powder has tasty tartaric acid which reacts withproduced during decomposition of and neutralizes it, so if tartaric acid is not present, the cake will taste bitter due to the presence of sodium carbonate                                                                                                                                      (ii) By adding tartaric acid to baking soda we can form baking powder.                                                                    (1) (iii) Tartaric acid neutralizes the sodium carbonate formed during decomposition of hence, it makes the cake tasty and not bitter intaste.                                                                                                                              (1) (b) The acid is formic acid (HCOOH). If baking soda (abase) is applied on the sting (biting area), it givesrelief.                                   (1 x 2) Or (a) X is calcium carbonate.                                                                                                                  (1) Solution Y is lime water                                                                                                                            (1/2) During electrolysis of brine, gas is released at anode. So, gas G is Cig gas (chlorine gas).           (1/2)                                                                                                                     (1/2) Hence, Z is calcium oxychloride (bleaching powder).                                                                                        (1/2) (ii) Egg shells are made up of calcium carbonate.                                                                                               (1) So, brisk effervescence due to the liberation of CO2 gas is observed. There action is                                                                                                               (1)