Heat of combustion is a chemical property that can be measured.
Explanation:
The reaction is as follows:
2Mg(s) + O2(g) ---> 2MgO(s)
and the researcher said that 32 g of MgO was produced.
Stoichiometry:
28 g Mg × (1 mol Mg/24.305 g Mg) = 1.15 mol Mg
15 g O2 × (1 mol O2/15.999 g O2) = 0.938 mol O2
1.15 mol Mg × (2 mol MgO/2 mol MgO) = 1.15 mol MgO
1.15 mol MgO × (40.3044 g MgO/1 mol MgO) = 46.6 g MgO
0.938 mol O2 × (2 mol MgO/1 mol O2) = 1.88 mol MgO
1.88 mol MgO × (40.3044 g MgO/1 mol MgO = 75.6 g MgO
Based on these numbers, the amount of product after the reaction is much less than expected so these results don't seem to support the law of conservation of matter.
By increasing the temperature.
The atom that is oxidized : Cr
The oxidizing agent : H₃PO₄
<h3>Further explanation</h3>
Reaction
2 H₃PO₄ (aq) + 2Cr(s) → 2 CrPO₄ (aq) + 3H₂(g)
Atoms undergoing a reduction reaction (decrease in oxidation number) and an oxidation reaction (increase in oxidation number)
H⁺(in H₃PO₄) =+1
H₂=0
Cr = 0
Cr³⁺(in CrPO₄ )
the oxidizing agent.⇒which undergoes a reduction reaction and oxidizes another compound/element : H₃PO₄