temp pract Flashcards
Explain the shape of graph before and after eqv point.
Before the eqv point, NAOH is the LR. Amt of water produced is equal to amt of NaOH. Since total volume is kept constant, As volume of NaOH increases, temp increases.
After the eqv point, H2S04 is the LR. Amt of water is constant as VH2S04 is constant. Since total volume is kept constant, no matter how much VNaOH increases, temp constant.
Does changing from HCL to H2S04 change enthalpy change?
No. As enthalpy change of the reaction is defined by amount of heat release per mole of magnesium
Why is using 5.00cm3 instead of 10cm3 of FA4 not recommended?
Incurs a higher percentage error when measuring smaller volume of FA4
effect on eqv volume and eqm temp when weaker acids used.
no change to volume as regardless of acid strength there is exactly equal amount of acid to neutralise by the alkaline at the eqv point
Temp decreases as some of heat released would be absorbed to allow complete dissociation of the weak acid
Why is the acid monobasic if temperature increased by twice?
Amount of water is doubled, hence any of heat liberated has also doubled as total volume is constant. This is shown with temp doubling. If acid was dibasic, and of water formed would have remained the same and temp would have been the same
Predict and explain the effect of adding the starch indicator at the start of the titration on the M. of CuSOnH.0.
Due to slow release of I3- from the starch I3 minus complex, the end point would have exceeded the equivalence point, leading to a larger titrate value. This leads to a larger smt of CuS04nh2o and a lower Mr
how is rate of rxn affected with a smaller conc used?
Rxn will be shorter as small amt of products will be formed hence lesser time to change blue black
why are aliquots added with sodium hydrogen carbonate
Quinch the rxn by reacting with acid catalyst
