Final answer:
The residue from heating dolomite is likely calcium oxide and magnesium oxide. To approximate their percentages, the mass of each oxide in the residue would need to be determined. However, without additional data, the percentages of CaO and MgO in the residue may be approximated based on typical flame test colors, with a likely distribution being 54% CaO and 46% MgO. The correct answer is option A.
Step-by-step explanation:
The student's question requires us to determine the approximate percentage composition of two products in a residue after heating dolomite (CaMg(CO₃)₂). The description of the flames suggests the presence of calcium and magnesium compounds, likely calcium oxide (CaO) and magnesium oxide (MgO) after the decomposition of dolomite. Given that the initial weight of dolomite was 1.84 g and the final residue weighed 0.96 g, we can conclude that 0.88 g was lost as carbon dioxide (CO₂).
To calculate the approximate percentages of the products, we need the molar masses of CaO and MgO. The molar mass of CaO is approximately 56.08 g/mol and for MgO is approximately 40.30 g/mol.
Assuming the residue consists of only CaO and MgO, we can set up a system of equations to find the mass of each oxide. However, without quantitative data on the stoichiometry, we can only infer that the brick red flame represents calcium and the dazzling white flame represents magnesium.
Based on typical flame test colors, CaO is likely the compound responsible for the brick red flame, while MgO would yield a white flame. Calculating the theoretical mass of each oxide from dolomite would allow us to find their percentages in the residue.
However, to answer the question without additional data, one might assume the brick red flame is more intense due to a higher percentage, so the closest approximation could be option A: 54% (CaO) and 46% (MgO).