Respuesta :
This substance's chemical formula is C₈H₈O₂ and To create the 0.8 M solution, 19.04 g of MgCl₂ must be dissolved in 250 mL of water.
How is a molecular formula composed?
The chemical formula for a chemical compound's molecular formula lists the variety of atoms that make up the molecule.
Briefing:
Assuming we have 100 g of the molecule, the masses of its constituent parts are as follows in order to get its molecular formula:
-70.6 g of carbon
-5.9 g of hydrogen
-23.5 g of oxygen
We next divide these masses by the molar masses of the constituent components to obtain the moles:
-carbon: 70.6 g / 12 g/mol = 5.88 mol
-hydrogen: 5.9 g / 1 g/mol = 5.9 mol
-oxygen: 23.5 g / 16 g/mol = 1.47 mol
To get the molar ratio, divide the moles by the least number (1.47 mol for oxygen):
-carbon: 5.88 mol / 1.47 mol = 4
-hydrogen: 5.9 mol / 1.47 mol = 4
-oxygen: 1.47 mol / 1.47 mol = 1
As a result, we have the empirical formula:
This empirical formula's molar mass is
4 x 12 g/mol + 4 x 1 g/mol + 16 g/mol = 68 g/mol
In order to arrive at our final result, we divide the molar mass of our compound by the molar mass of the empirical formula.
136 g/mol / 68 g/mol = 2
We multiply the index numbers by 2 to get the molecular formula C₈H₈O₂.
The following equation is used to determine how much MgCl2 is required to make a 0.8 M solution of it in 250 mL (0.250 L):
c = n/V ⇒ n = c * V
c - molarity of the solution (0.8 M)
n - number of moles of solute
V - the volume of the solution
Now we plug in the values we have:
n = 0.8 M * 0.250 L
n = 0.2 mol
Now, we can determine the mass of the solute using the molar mass of MgCl2 (M = 95.211 g/mol):
n = m/M
m = n * M
m - the mass of the substance
m = 0.2 mol * 95.211 g/mol
m = 19.04 g
Therefore, 19.04 g of MgCl2 are required to create a 0.8 M solution in 250 mL.
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