Question #9c2ab

2 Answers
Dec 25, 2017

Chemical reaction mechanisms conserve mass


Suppose this reaction:

#Na + 1/2 Cl_2 -> NaCl#

Reactants: Na 23 g; Cl 35.5 g (elemental weights).

It means 23 grams of sodium (1 mol) and 35.5 grams of #Cl_2# (note that #Cl_2# has a mass of 71 grams) form 58.5 grams of table salt. Mass is conserved.

When a chemical reaction is written down, it provided both qualitative and quantitative information. Qualitatively we can see which chemicals are interacting to form which end products. Stochiometrically the mass is conserved. In other words, the balancing of equations so that the same number of each kind atom appears on each side of the equation and the subsequent calculations, which could be used to determine amounts of each compound involved.

Dec 25, 2017

Please refer to the explanation below...


  1. First thing to do is to write and balance the given equation;
  2. Per convention, if given data are expressed in grams, convert it to moles before taking any intermediate calculations;
  3. Identify involved compounds and find its molar masses for the usual molar conversion. Molar masses are obtainable from the periodic table which are the summation of the relative atomic masses of elements composing the involved compounds;
  4. With reference to the balanced equation, mole ratios between the involved compounds are also obtainable. These relationships serve as the equivalence statements where possible conversion factors are taken;
  5. Make sure the correct conversion factors are chosen to ensure that the desired unit is attained;
  6. Lastly, since mass is required in the problem, again use the molar mass of that particular compound to convert the derived mole to gram;
  7. Before the finalization of the answer, check every step to ensure that every calculation is well presented and with sense.