Question

10L of 2M NaCl is subjected to the following change
calculate final molarity.
heated until volume reduced to 40%
heated until volume reduced by 40%

Answer 1

Answer:

∴ 10 L OF 2M NaCl

∵ M = MOLES/ LITRE

∴ NO. OF MOLES OF NaCl = 20 MOLES

⇒ i) ∵ THE VOLUME REDUCED TO 40%

      ∴THE VOLUME = 10×40 /100

                                 = 4 L

SO , NOW THE MOLARITY , M = MOLES /LITRE

                                                    = 20 / 4

                                                    = 5 M

∴   MOLARITY OF THE SOLUTION = 5 M SOLUTION

ii) ∵ THE VOLUME REDUCED BY 40% = 100% - 40%

                                                          = 60% i.e. THE VOLUME IS NOW  60%

   ∴THE VOLUME = 10×60 /100

                              = 6 L

∴ MOLARITY = 20/ 6

                     = 3.33 M

HOPE IT HELPS YOU :-)))