Answer and Explanation:
Aspirin is odorless, but when left exposed to air in the environment, it gradually hydrolyzes into salicylic acid and acetic acid as that is the precursor for synthesizing Aspirin.
Using this hydrolyzed aspirin for titration would not be advised, because it would affect the reading of the titration. Ordinarily, apsirin is a weak acid and direct titration of aspirin is problematic because it hydrolyzes pretty fast to salicylic acid— leading to an unwanted side reaction which may or may not go to completion. Therefore, excess base must be added and heat is supplied to the mixture so that neutralization and hydrolysis are complete. The remaining base is then titrated. This is called back titration.
Now, in back titration, instead of using solution whose concentration is expected to be known, we rather use excess volume of reactant which has been left over after the completion of a reaction with the analyte.
In this case, we use an alkali, preferably NaOH (1.0 mol/dm³). Te unused NaOH remaining after the hydrolysis is titrated against a standard HCl (0.1 mol/dm³). Then from the reaction equation of the aspirin and sodium hydroxide, the amount of NaOH required for the hydrolysis can be calculated.
Answering whether the titration goes up or down, it would be observed that the titration reading would GO DOWN because the exposed aspirin used has experienced some form of hydrolysis before it was used for titration, so the hydrolysis reaction it would undergo with acetyl-salicylic acid would be minimal, and this would affect the titration reading.
But if the aspirin wasn't left exposed to the environment, the reading would go up since more hydrolysis would take place in this case.
Energy is either released or absorbed is the correct option.
Hope this helps!
The bottom of group 1. Francium (or Fr) is the element with the greatest metallic properties.
Francium is not a naturally-occurring element, however. It is man-made. There is an isotope of francium that exists naturally, but it's half life is so short that it decays almost instantly into a different element.
The naturally-occurring element with the highest metallic properties is cesium (or Cs), located right above francium.
Metallic characteristics decrease as you move from left to right on the periodic table.
The molar mass of methanol is 12.01 + 4.04 + 16 = 32.05 g/mol
230.0 g of methanol / 32.05 g/mol = 7.176 mol methanol
The heat of combustion of methanol (CH3OH or CH4O) is -715.0 kJ/mol. (Negative sign means the energy is released)
Multiplying 7.176 mol by -715.0 kJ/mol gives -5,131 kJ.