a mixture containing CaCO3 and CaO only. When 0.3500 g of mixture was ignited and cooled, the wt of mixture was 0.3400 g. Calculate %CaO in original mixture.
When heated, the CaCO3 decomposes to CaO and CO2 as follows:
CaCO3 ==> CaO(s) + CO2(g)
The CaO there initially is unchanged with the heating.
So the mixture initially weighed 0.3500 and after heating it weighed 0.3400; therefore, the CO2 lost must be 0.3500-0.3400 = ??
Convert mass CO2 to mass CaCO3. The rest of it must have been the CaO there initially.
To calculate the percentage of CaO in the original mixture, we need to determine the amount of CaO present in the ignited mixture and then use that to find the percentage.
First, let's find the amount of CaO in the ignited mixture:
1. Calculate the weight loss:
Weight loss = Weight of initial mixture - Weight of ignited mixture
Weight loss = 0.3500 g - 0.3400 g
Weight loss = 0.0100 g
2. Since the ignited mixture consists of only CaCO3 and CaO, the weight loss is due to the loss of CO2 from CaCO3. The molar mass of CO2 is 44.01 g/mol. So, to find the amount of CaO:
Moles of CO2 = Weight loss / Molar mass of CO2
Moles of CO2 = 0.0100 g / 44.01 g/mol
3. Since the reaction between CaCO3 and CO2 is 1:1, the moles of CaO will be equal to the moles of CO2:
Moles of CaO = Moles of CO2
4. Now, calculate the weight of CaO:
Weight of CaO = Moles of CaO x Molar mass of CaO
Finally, we can use the weight of CaO in the ignited mixture to calculate the percentage of CaO in the original mixture:
Percentage of CaO = (Weight of CaO รท Weight of original mixture) x 100
Remember, in this case, the original mixture consisted only of CaCO3 and CaO.