Chemical equilibrium is achieved when the rates of 2 reactions become equal.Does this mean there are 2 reactions going on? like.for example,in solid-liquid equilibrium rate of freezing is said to be equal to rate of melting. Does this mean both freezing and melting take place simultaneously in a closed vessel?

@ azad 
yes , you are correct , the thing is both forward and backward reaction should have to running on the same vessel . only then if the two rates will be equal , then equilibrium will be acheived . 
and when u are talking abt the freezing and melting of ice , same thing happens also their . 
equilibrium 
rate of forward reaction = rate of backward reaction 
HOPE U UNDERSTAND THAT 
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