Moles --> Grams and Grams --> Moles problems?

I am studying how to figure out how many moles are in a certain mass of a substance and how many grams in a certain amount of moles. Could you post some practice problems that I could work on?

Moles --%26gt; Grams and Grams --%26gt; Moles problems?
There's a couple of practice questions at the end..





...A 'Mole' of a compound is defined as "The number of grams (or other weight (mass) unit of the compound that is equal to its Molecular weight (Mass)".


...A mole may be called 'Gram-mole'; 'Lb-mole'; 'Kilo-mole' ..etc.


...e.g. The Mol. Wt. of water (H2O) = 2 + 16 = 18.


...18 grams of water is called 1 g-mole or 18 lbs of water is called 1 lb-mole.





...From this we can calculate the number of 'Kilo-moles'in 900 kg of water.


...Divide the number of Kg by the mol.wt.


...= 900 ÷ 18 = 50 kilo-moles of water.


...A mole is represented by the formula of the compound. e.g. water, H2O = 1 mole of water.


...To show more than 1 mole, a number is placed in front of the formula. e.g. 3H2O = 3 moles of water.


...Example: Take 20 lb of NaCl; Mol.wt of NaCl = 23 + 35 = 58.


...Number of moles of NaCl = 20 lb ÷ 58 lb-mole = 0.345 lb-mole.





Try these examples: -


... How many Kilo-moles in 12 kg of CO2 ?


...Ans: CO2 = Mol.wt. = ?


.........= ? 0.273 kg-mole.


...How many Gram-moles in 24g of H2SO4 ?


...Ans: H2SO4 = Mol.wt. = ?


........... ? = 0.245 g-mole.


...Now:Make up some for yourself.
Reply:1. What is the mass of 0.25 moles of CO2?





2. How many moles of methane are there in 320g of CH4?





3. What is the mass of 5 moles of ammonium sulphate, (NH4)2SO4?





4, How many moles of sodium chloride are there in 175.5g of NaCl?