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This guide explains key concepts in chemistry including moles, ions, and atomic mass. It highlights the fact that one mole of chloride ions (Cl-) contains 6.022 x 10^23 ions, the same number as a mole of xenon atoms. We delve into the difference in mass between these particles, emphasizing that while the particle count is identical, their masses differ. We also discuss molar mass, empirical vs. molecular formulas, and significant figures. Essential calculations such as average atomic mass and percent composition checks are covered, along with the application of Avogadro’s number.
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What do a mole of chloride ions and a mole of xenon atoms have in common?
They both have the same amount of particles; 6.022 x 1023 particles
Does a mole of Xenon have the same mass as a mole of chloride ions?
No, according to the periodic table, each substance has a different mass. They just are the same number of particles.
Turn the previous question and answer into a conversion factor.
1 mol Cl35.45g Cl 35.45g Cl or 1 mol Cl
If a test question asked you to calculate average atomic mass what numerical data would have to be given in the problem?
Explain the difference between molecular and empirical formulas.
The empirical formula is the simplified ratio and the molecular formula is how the molecule actually exists.
What is the formula you use to help you determine a molecular formula?
How can you check your answer in a percent composition problem to make sure there are no obvious errors?
How can you double check your answer in an average atomic mass problem?
Make sure the final average in amu is between the masses given in the problem.
Particles, ions, atoms, molecules, and formula units. That means whenever you write 6.022 x 1023 you must have one of those units behind it. NOT g or mol.
Tell whether the following is an atom or molecule. CO2 H2O Al H2
CO2 molecule H2O molecule Al atom H2 molecule
How many conversions would you use if the given was atoms and the find was grams?