Answer:
A. Students made a measurement error, because ending with more products is impossible.
Explanation:
The law of conversation of matter tells us that in a chemical reaction, matter is never created or destroyed, it's simply converted from one form to another. So the mass of reactants should always equal the mass of the products in a chemical reaction. If there is excess mass in the product, the students have made an error of some kind.
Answer: The mass percentage of
is 5.86%
Explanation:
To calculate the mass percentage of
in the sample it is necessary to know the mass of the solute (
in this case), and the mass of the solution (pesticide sample, whose mass is explicit in the letter of the problem).
To calculate the mass of the solute, we must take the mass of the
precipitate. We can establish a relation between the mass of
and
using the stoichiometry of the compounds:

Since for every mole of Tl in
there are two moles of Tl in
, we have:

Using the molar mass of
we have:

Finally, we can use the mass percentage formula:

Answer:
this is a oxidation reaction
product is magnesium oxide
the balanced equation is
2Mg + O2 -> 2MgO
Answer: B its most likely