A 21.0054 g sample of impure magnesium carbonate was heated to complete decomposition
according to the equation
MgCO3(s) → MgO(s) + CO2(g) .
After the reaction was complete, the solid
residue (consisting of MgO and the original
impurities) had a mass of 19.0732 g. Assuming that only the magnesium carbonate had
decomposed, how much magnesium carbonate was present in the original sample?
Answer in units of g
To find the amount of magnesium carbonate present in the original sample, we need to determine the mass of magnesium carbonate that had decomposed during the reaction.
First, let's find the mass of the solid residue that consists of MgO and the original impurities. Given that the mass of the residue is 19.0732 g, we need to subtract this from the mass of the original sample to find the mass of the decomposed magnesium carbonate.
Mass of residue = 19.0732 g
Now, we can calculate the mass of decomposed magnesium carbonate by subtracting the mass of the residue from the mass of the original sample:
Mass of original sample - Mass of residue = Mass of decomposed magnesium carbonate
Mass of decomposed magnesium carbonate = 21.0054 g - 19.0732 g
Mass of decomposed magnesium carbonate = 1.9322 g
Therefore, the amount of magnesium carbonate present in the original sample is 1.9322 g.