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secondary 3 | Biology
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(Chemistry) What is the most important thing I should take note of when doing mole questions? Are there any common mistakes made by students? For some reason moles is my worst topic; I just don’t get it. Some advice is much appreciated!!!:”)))
Date Posted: 6 years ago
Views: 342
Just remember 2 things: (1) Mr x Mol = Mass, so 1mol of C-12 atoms = 12g, and (2) Watch the units. For an equation to balance, the units must balance as well. Just observe the given units, and try to work your way towards the final unit.
Practice more questions. Students solve their mole concept issues after ensuring their writing out and balancing of equations is practically flawless. This is the first important step towards success with the mole concept. No proper equation = no basis of solving.
Take a good qn with worked solutions and stare at it until you know where each number comes from (either qn, periodic table or formula) and it'll just click in. It worked for me at least.
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There is no particular part in the notes that you need to take note of. Every part is important because questions can come from any part. To approach the topic, I break down into step by step what you need to understand first before proceeding to the next step.
1. 1 mole is 6* 10^23 particles.
2. Relative atomic mass is the mass of 1 mole of atoms.
3. Relative molecular mass is the mass of 1 mole of molecules.
4.From the relative molecular mass, you can find out the empirical formula of a molecule. For example, the relative atomic mass of carbon from the periodic table is 12 and oxygen is 16. If we are given the relative molecular mass of a substance that contains C and O is 44, then we know that there is one atom of carbon and two atoms of oxygen. The empirical formula should then be CO2.
5. The volume of 1 mole of gas is 24 dm3.
6.number of moles /24 is the number of moles of gas in 1 dm3 of gas.
7.concentration= number of moles/volume of gas (expressed in moldm-3) or
= number of moles/mass of as (expressed in molg-1)
After you understand the concepts, you have to try the various questions.
Remember, practice makes perfect.
1. 1 mole is 6* 10^23 particles.
2. Relative atomic mass is the mass of 1 mole of atoms.
3. Relative molecular mass is the mass of 1 mole of molecules.
4.From the relative molecular mass, you can find out the empirical formula of a molecule. For example, the relative atomic mass of carbon from the periodic table is 12 and oxygen is 16. If we are given the relative molecular mass of a substance that contains C and O is 44, then we know that there is one atom of carbon and two atoms of oxygen. The empirical formula should then be CO2.
5. The volume of 1 mole of gas is 24 dm3.
6.number of moles /24 is the number of moles of gas in 1 dm3 of gas.
7.concentration= number of moles/volume of gas (expressed in moldm-3) or
= number of moles/mass of as (expressed in molg-1)
After you understand the concepts, you have to try the various questions.
Remember, practice makes perfect.
Date Posted:
6 years ago
Thank you!!!!:’)))
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