Question
How would you distinguish between baking powder and washing soda by heating?
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Answer
Baking soda is sodium hydrogen carbonate $\left( NaHCO _3\right)$ which forms sodium carbonate $\left( Na _2 CO _3\right)$, water and carbon dioxide gas while heating. $2 NaHCO _3 \rightarrow Na _2 CO _3+ H _2 O + CO _2 \uparrow$
Presence of $CO _2$ can be detected with the help of lime water which turns milky after reacting with carbon dioxide gas
Washing soda is sodium carbonate deca-hydrate $\left( Na _2 CO _3 \cdot 10 H _2 O \right)$ which means there are 10 water molecules present with crystal hence named as water of crystallization
On heating washing soda, it becomes anhydrous and presence of water of crystallization can be detected with the help of anhydrous $CuSO _4$ which shows colour change from white to blue with moisture.
$Na _2 CO _3 \cdot 10 H _2 O \rightarrow Na _2 CO _3+10 H _2 O$
Presence of $CO _2$ can be detected with the help of lime water which turns milky after reacting with carbon dioxide gas
Washing soda is sodium carbonate deca-hydrate $\left( Na _2 CO _3 \cdot 10 H _2 O \right)$ which means there are 10 water molecules present with crystal hence named as water of crystallization
On heating washing soda, it becomes anhydrous and presence of water of crystallization can be detected with the help of anhydrous $CuSO _4$ which shows colour change from white to blue with moisture.
$Na _2 CO _3 \cdot 10 H _2 O \rightarrow Na _2 CO _3+10 H _2 O$
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Column I
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Column II
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(ii)
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(i)
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