in My book i studied a activity i saw that - 1.)2Na + 2H2O = 2NaOH + H2 2.)Zn + H2O = ZnO + H2 IN YTHE FIRST EQUATION IN MY BOOK THEY SHOWED A ARROW POINTING UPWARDS AFTER H2 BUT IN SECOND EQUAION THEY DID NOT SHOW ARROW PINTING UPWARDS AFTER H2 CAN OU STATET THE RESON FOR THIS. AND ALSO TELL THAT IF WE BRING A BURNING MATCHSTICK NEAR THE SECOND RECTION WILL THE MATCHSTCK BURN WITH A POP SOUND?

CBSE Class 8 Answered

in My book i studied a activity i saw that -

1.)2Na + 2H2O = 2NaOH + H2

2.)Zn + H2O = ZnO + H2

IN YTHE FIRST EQUATION IN MY BOOK THEY SHOWED A ARROW POINTING UPWARDS AFTER H2

BUT IN SECOND EQUAION THEY DID NOT SHOW ARROW PINTING UPWARDS AFTER H2

CAN OU STATET THE RESON FOR THIS. AND ALSO TELL THAT IF WE BRING A BURNING MATCHSTICK NEAR THE SECOND RECTION WILL THE MATCHSTCK BURN WITH A POP SOUND?

Asked by yogeshmittal177 | 23 Oct, 2015, 08:49: PM

Expert Answer

In both the reactions, H₂ gas liberates as a byproduct.
But not everytime the chemical reaction is represented with all its state symbols.
In the second equation, one of the byproduct that is ZnO is a precipoitate which can be shown with the help of downward arrow (↓) beside it.
So it is not a printing mistake, It is understood that H₂ liberates as a gasin both the cases. In first case it is expressed with upward arrow while in the second case it is not expressed.
In both the reaction, if we bring a burning matchstick near the reaction vessel, it burns with pop sound due to liberationon of H₂ gas.

Answered by Prachi Sawant | 25 Oct, 2015, 12:35: PM