first and second ionisation energies of mg are 740 and 1450 jmol-1 calculate percentage of mg+and mg2+ of 1g of mg absorbs 50 kj of energy
To calculate the percentages of Mg+ and Mg2+ when 1g of Mg absorbs 50 kJ of energy, we need to use the ionization energies and the given amount of energy.
1. Convert the given energy from kJ to J:
50 kJ = 50,000 J (since 1 kJ = 1000 J)
2. Calculate the total ionization energy required to completely ionize Mg by summing up the first and second ionization energies:
Total Ionization Energy = First Ionization Energy + Second Ionization Energy
Total Ionization Energy = 740 J/mol + 1450 J/mol
Total Ionization Energy = 2190 J/mol
3. Calculate the number of moles of Mg in 1g using its molar mass:
Molar Mass of Mg = 24.31 g/mol (approximately)
Number of Moles of Mg = Mass of Mg / Molar Mass of Mg
Number of Moles of Mg = 1g / 24.31 g/mol
4. Calculate the total ionization energy required to ionize 1g of Mg:
Total Ionization Energy of 1g of Mg = Total Ionization Energy * Number of Moles of Mg
Total Ionization Energy of 1g of Mg = 2190 J/mol * (1g / 24.31 g/mol)
5. Calculate the percentage of Mg+ and Mg2+ based on the given energy:
Percentage of Mg+ = (First Ionization Energy / Total Ionization Energy of 1g of Mg) * 100
Percentage of Mg2+ = (Second Ionization Energy / Total Ionization Energy of 1g of Mg) * 100
Substitute the values into the formulas and perform the calculations to find the percentages of Mg+ and Mg2+.
This answer is incorrect
No. Of moles of mg present in 1g = 1/24 = 0.0417
Energy absorbed in the ionization of 0.0417 mole of Mg to Mg+ = 0.0417×740 = 30.83 kJ
Energy left unused = 50- 30.83 = 19.17kJ
Please check your post. I think that's 740 kJ/mol and 1450 kJ/mol and not J/mol. I would look at it this way.
Convert 1 g Mg to mols = about 0.04 but you can be more exact t6han that.
0.04 x 740 = about 30 kJ
That leaves you 20 kJ of the total of 50 kJ.
How much will that 20 do for the 2nd ion at 1450 each? That will be about 20/1450 or about 0.01 mol.
Total ionized = 0.01+0.04 = 0.05
That is about 20% and 80% for 2nd and 1st respectively. Check my thinking.