Practice Exercise
1.) How many moles are in 28 grams of CO2 ?
2.) What is the mass of 5 moles of Fe2O3 ?
3.) Determine the number of molecules of 14 g of nitrogen dioxide (NO2).
4.) Find the mass, in grams, of 1.00 x 1023 molecules of N2.
5.) NaHCO3 (Sodium-bi-carbonate ion)
Baking powder is the compound consisting of sodium, hydrogen, and carbonate ions. It is used in baking cakes and desserts. It is also used in neutralizing stomach acidity. Moreover, it can be used as a natural deodorant. Calculate the percent composition of Baking Powder.
6.) Phenol (C6H5OH ) is proven to be effective anti-bacterial, anti-fungi and anti-viral agent. It is commonly used disinfectants. Calculate the percent composition of phenol.
1.) How many moles are in 28 grams of CO2 ?
2.) What is the mass of 5 moles of Fe2O3 ?
3.) Determine the number of molecules of 14 g of nitrogen dioxide (NO2).
4.) Find the mass, in grams, of 1.00 x 1023 molecules of N2.
5.) NaHCO3 (Sodium-bi-carbonate ion)
Baking powder is the compound consisting of sodium, hydrogen, and carbonate ions. It is used in baking cakes and desserts. It is also used in neutralizing stomach acidity. Moreover, it can be used as a natural deodorant. Calculate the percent composition of Baking Powder.
6.) Phenol (C6H5OH ) is proven to be effective anti-bacterial, anti-fungi and anti-viral agent. It is commonly used disinfectants. Calculate the percent composition of phenol.
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Answer:
1.) Mol in 28 g CO2 = 28 g / 44 g/mol = 0.64 mol - 2 significant digits.
2.)1st find Molar Mass of fe 02 Fe = (55.85)/2) = 111.7g Total = 159.78] Smol l 159.79 rezoz - 799 Garans Poon BO=(16Y3) - 489 Timol = 798.5 3. Find the number of moles of argon in 452 g of argon.
3.)We must give here N2 not N because N is only atom and N2 is the molecule
Molar mass : The mass of the one mole of the substance is called molar mass.
Molar mass of the nitrogen = N2 = 2×14u = 28u
We know that
Mass = number of moles × molar mass
14 = number of moles × 28
14/28 = number of moles
0.5 = number of moles
1 mol of my substance contains exactly the avogadro number of molecules i.e 6.022×10^23
Therefore
Molecules = number of moles × 6.022×10^23
Molecules = 0.5 × 6.022 × 10^23
Molecules = 3.011×10^23 “ Nitrogen (N2) molecules
4.)One mole of any substance contains 6.022×1023 atoms/molecules. The molar mass of N2 is 28.0134 g mol-1. Mass of N2 is 4.65 grams
5.)Sodium bicarbonate (IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion (HCO3−).
6.)