Given a 10.0g sample of MgCO3*5H2O, what weight of anhydrous magnesium carbonate can be obtained after driving off the water?
The GFM of the sample is 174.3amu. Now.. how do I go about finding the weight of the magnesium carbonate?
magnesium carbonate consist of one atom of Mg,one atom of c,three atoms of O.SO weight of magnesium carbonate is
24 + 12 + (3*16)
=24 +12+ 48
=84
To find the weight of anhydrous magnesium carbonate (MgCO3) obtained after driving off the water, we need to consider the percent composition of the hydrate MgCO3*5H2O.
Step 1: Calculate the molecular weight of MgCO3*5H2O:
The molecular weight of the hydrate can be calculated by adding the atomic masses of all the elements present in the formula:
MgCO3: 1(Mg) + 1(C) + 3(O) = 84.3 amu
5H2O: 5(H) + 10(O) = 90 amu
Therefore, the molecular weight of MgCO3*5H2O is:
84.3 amu + 90 amu = 174.3 amu
Step 2: Calculate the molar mass of water (H2O):
The molar mass of water is calculated by adding the atomic masses of hydrogen (H) and oxygen (O):
2(H) + 1(O) = 18 amu
Step 3: Calculate the molar mass of water in the hydrate (MgCO3*5H2O):
Since there are five molecules of water present in the hydrate, the molar mass of water in the hydrate is:
5 x 18 amu = 90 amu
Step 4: Calculate the molar mass of anhydrous magnesium carbonate (MgCO3):
The molar mass of anhydrous magnesium carbonate can be calculated by subtracting the molar mass of water in the hydrate from the molar mass of the hydrate:
174.3 amu - 90 amu = 84.3 amu
Step 5: Calculate the weight of anhydrous magnesium carbonate:
Given a 10.0 g sample of MgCO3*5H2O, we can use the molar mass of anhydrous magnesium carbonate to find the weight:
Weight = (molar mass of anhydrous magnesium carbonate / molar mass of MgCO3*5H2O) x weight of the sample
Weight = (84.3 amu / 174.3 amu) x 10.0 g
Calculating this expression gives the weight of anhydrous magnesium carbonate obtained after driving off the water from the sample.