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What Will Be Given: Grams of an Element or Compound
What To Calculate: Moles
Explanation:
Many chemical calculations require the number of moles of the element or compound. The common way to find the moles is to convert the given mass in grams to moles.
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Steps to convert Grams to Moles
- Determine the molecular formula of the molecule.
- Find the atomic mass of each element in the molecule.
- Find molecular mass by Multiply each element’s atomic mass by the number of atoms of that element in the molecule.
- Divide the number of grams of the compound by the molecular mass to get the number of moles of the compound. Number of Moles = Mass of Compound / Molecular Mass of the compound
Tips and Tricks
In your problem, when you are given a value in moles, you can convert it to grams by multiplying the number of moles by molecular mass of the compound or element. Refer Example-2.
- Grams of Element = (Molecular mass of Compound) x (moles)
Example -1 : Grams to Moles
Determine the number of moles of CO2 in 480 grams of CO2.
Atomic mass of C = 12Atomic mass of O = 16Molecular mass of CO2=12 x 1 + 2 x 16 = 44One mole of CO2 weighs 44 gramsX moles of CO2 weighs 480 grams
X moles CO2 = 480 g x 1 mol/44 g = 10.9 moles
There are 10.9 moles CO2 in 480 grams of CO2
Example-2 : Moles to Grams
Determine the mass in grams of 3.60 mol of H2SO4.
Solution
Atomic mass of Hydrogen = 1
Atomic Mass of Sulfur = 32
Atomic Mass of Oxygen = 16
Molecular Mass of H2SO4 = 2 x 1 + 1 x 32 + 4 x 16= 98
One Mole of H2SO4 weights 98 grams
3.60 moles of H2SO4 weighs X grams
X grams = 3.6 x 98 = 352.8
3.60 moles of H2SO4 weighs 353 grams
Related Questions
- If the equivalent weight of an element is 32, then the percentage of oxygen
- Magnesium carbonate of x g decomposes. What is the percentage of purity
- The percentage weight of Zn in white vitriol [ZnSO₄ 7H₂O] is approximately equal
Subject: Chemistry (2512)
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