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Acids, Bases and Salts — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceAcids, Bases and Salts4 Marks
Question
Baking soda is used in small amounts for making bread and cakes. It helps to make these soft and spongy. An aqueous solution of baking soda turns red litmus blue. It is also used in soda acid fire extinguisher. Use this information to answer the following questions.
(i) Write the equation for the reaction between baking soda and acid.
(ii) How does it help in extinguishing fire?
(iii) What is the reaction involved when it is heated?
or
(iv) Is the $pH$ value of baking soda solution lower than or higher than 7 ?
✓

Answer

(i) The equation for the reaction is
$2 NaHCO _3( s )+ H _2 SO _4( aq )$
(Baking soda)
$\longrightarrow Na _2 SO _4( s )+2 H _2 O (l)+2 CO _2(g)$
(ii) The $CO _2$ gas produced by the reaction of baking soda and acid in the soda-acid fire extinguisher, helps in extinguishing fire.
(iii) The reaction involved is
$2 NaHCO _3( s ) \stackrel{\Delta}{\longrightarrow} Na _2 CO _3( s )+ H _2 O (l)+ CO _2( g ) \uparrow$
or
(iv) The $pH$ value of baking soda solution in higher than 7, i.e. it is alkaline.

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